Merge branch 'develop' into fix/csp-mediaproxy-base-url

2020-06-11 10:25:00 -05:00 · 2020-06-11 10:25:00 -05:00 · 8a59fde0e5
parent 99afc7f4e4 5d6ec6e5fc
commit 8a59fde0e5
81 changed files with 3930 additions and 148 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - **Breaking:** removed `with_move` parameter from notifications timeline.

 ### Added
+- Chats: Added support for federated chats. For details, see the docs.
 - ActivityPub: Added support for existing AP ids for instances migrated from Mastodon.
 - Instance: Add `background_image` to configuration and `/api/v1/instance`
 - Instance: Extend `/api/v1/instance` with Pleroma-specific information.
--- a/docs/API/chats.md
+++ b/docs/API/chats.md
@ -0,0 +1,248 @@
+# Chats
+
+Chats are a way to represent an IM-style conversation between two actors. They are not the same as direct messages and they are not `Status`es, even though they have a lot in common.
+
+## Why Chats?
+
+There are no 'visibility levels' in ActivityPub, their definition is purely a Mastodon convention. Direct Messaging between users on the fediverse has mostly been modeled by using ActivityPub addressing following Mastodon conventions on normal `Note` objects. In this case, a 'direct message' would be a message that has no followers addressed and also does not address the special public actor, but just the recipients in the `to` field. It would still be a `Note` and is presented with other `Note`s as a `Status` in the API.
+
+This is an awkward setup for a few reasons:
+
+- As DMs generally still follow the usual `Status` conventions, it is easy to accidentally pull somebody into a DM thread by mentioning them. (e.g. "I hate @badguy so much")
+- It is possible to go from a publicly addressed `Status` to a DM reply, back to public, then to a 'followers only' reply, and so on. This can be become very confusing, as it is unclear which user can see which part of the conversation.
+- The standard `Status` format of implicit addressing also leads to rather ugly results if you try to display the messages as a chat, because all the recipients are always mentioned by name in the message.
+- As direct messages are posted with the same api call (and usually same frontend component) as public messages, accidentally making a public message private or vice versa can happen easily. Client bugs can also lead to this, accidentally making private messages public.
+
+As a measure to improve this situation, the `Conversation` concept and related Pleroma extensions were introduced. While it made it possible to work around a few of the issues, many of the problems remained and it didn't see much adoption because it was too complicated to use correctly. 
+
+## Chats explained
+For this reasons, Chats are a new and different entity, both in the API as well as in ActivityPub. A quick overview:
+
+- Chats are meant to represent an instant message conversation between two actors. For now these are only 1-on-1 conversations, but the other actor can be a group in the future.
+- Chat messages have the ActivityPub type `ChatMessage`. They are not `Note`s. Servers that don't understand them will just drop them.
+- The only addressing allowed in `ChatMessage`s is one single ActivityPub actor in the `to` field.
+- There's always only one Chat between two actors. If you start chatting with someone and later start a 'new' Chat, the old Chat will be continued.
+- `ChatMessage`s are posted with a different api, making it very hard to accidentally send a message to the wrong person.
+- `ChatMessage`s don't show up in the existing timelines.
+- Chats can never go from private to public. They are always private between the two actors.
+
+## Caveats
+
+- Chats are NOT E2E encrypted (yet). Security is still the same as email.
+
+## API
+
+In general, the way to send a `ChatMessage` is to first create a `Chat`, then post a message to that `Chat`. `Group`s will later be supported by making them a sub-type of `Account`.
+
+This is the overview of using the API. The API is also documented via OpenAPI, so you can view it and play with it by pointing SwaggerUI or a similar OpenAPI tool to `https://yourinstance.tld/api/openapi`.
+
+### Creating or getting a chat.
+
+To create or get an existing Chat for a certain recipient (identified by Account ID)
+you can call:
+
+`POST /api/v1/pleroma/chats/by-account-id/:account_id`
+
+The account id is the normal FlakeId of the user
+```
+POST /api/v1/pleroma/chats/by-account-id/someflakeid
+```
+
+If you already have the id of a chat, you can also use
+
+```
+GET /api/v1/pleroma/chats/:id
+```
+
+There will only ever be ONE Chat for you and a given recipient, so this call
+will return the same Chat if you already have one with that user.
+
+Returned data:
+
+```json
+{
+  "account": {
+    "id": "someflakeid",
+    "username": "somenick",
+    ...
+  },
+  "id" : "1",
+  "unread" : 2,
+  "last_message" : {...}, // The last message in that chat
+  "updated_at": "2020-04-21T15:11:46.000Z"
+}
+```
+
+### Marking a chat as read
+
+To mark a number of messages in a chat up to a certain message as read, you can use
+
+`POST /api/v1/pleroma/chats/:id/read`
+
+
+Parameters:
+- last_read_id: Given this id, all chat messages until this one will be marked as read. Required.
+
+
+Returned data:
+
+```json
+{
+  "account": {
+    "id": "someflakeid",
+    "username": "somenick",
+    ...
+  },
+  "id" : "1",
+  "unread" : 0,
+  "updated_at": "2020-04-21T15:11:46.000Z"
+}
+```
+
+### Marking a single chat message as read
+
+To set the `unread` property of a message to `false`
+
+`POST /api/v1/pleroma/chats/:id/messages/:message_id/read`
+
+Returned data:
+
+The modified chat message
+
+### Getting a list of Chats
+
+`GET /api/v1/pleroma/chats`
+
+This will return a list of chats that you have been involved in, sorted by their
+last update (so new chats will be at the top).
+
+Returned data:
+
+```json
+[
+   {
+      "account": {
+        "id": "someflakeid",
+        "username": "somenick",
+        ...
+      },
+      "id" : "1",
+      "unread" : 2,
+      "last_message" : {...}, // The last message in that chat
+      "updated_at": "2020-04-21T15:11:46.000Z"
+   }
+]
+```
+
+The recipient of messages that are sent to this chat is given by their AP ID.
+No pagination is implemented for now.
+
+### Getting the messages for a Chat
+
+For a given Chat id, you can get the associated messages with
+
+`GET /api/v1/pleroma/chats/:id/messages`
+
+This will return all messages, sorted by most recent to least recent. The usual
+pagination options are implemented.
+
+Returned data:
+
+```json
+[
+  {
+    "account_id": "someflakeid",
+    "chat_id": "1",
+    "content": "Check this out :firefox:",
+    "created_at": "2020-04-21T15:11:46.000Z",
+    "emojis": [
+      {
+        "shortcode": "firefox",
+        "static_url": "https://dontbulling.me/emoji/Firefox.gif",
+        "url": "https://dontbulling.me/emoji/Firefox.gif",
+        "visible_in_picker": false
+      }
+    ],
+    "id": "13",
+    "unread": true
+  },
+  {
+    "account_id": "someflakeid",
+    "chat_id": "1",
+    "content": "Whats' up?",
+    "created_at": "2020-04-21T15:06:45.000Z",
+    "emojis": [],
+    "id": "12",
+    "unread": false
+  }
+]
+```
+
+### Posting a chat message
+
+Posting a chat message for given Chat id works like this:
+
+`POST /api/v1/pleroma/chats/:id/messages`
+
+Parameters:
+- content: The text content of the message. Optional if media is attached.
+- media_id: The id of an upload that will be attached to the message.
+
+Currently, no formatting beyond basic escaping and emoji is implemented.
+
+Returned data:
+
+```json
+{
+  "account_id": "someflakeid",
+  "chat_id": "1",
+  "content": "Check this out :firefox:",
+  "created_at": "2020-04-21T15:11:46.000Z",
+  "emojis": [
+    {
+      "shortcode": "firefox",
+      "static_url": "https://dontbulling.me/emoji/Firefox.gif",
+      "url": "https://dontbulling.me/emoji/Firefox.gif",
+      "visible_in_picker": false
+    }
+  ],
+  "id": "13",
+  "unread": false
+}
+```
+
+### Deleting a chat message
+
+Deleting a chat message for given Chat id works like this:
+
+`DELETE /api/v1/pleroma/chats/:chat_id/messages/:message_id`
+
+Returned data is the deleted message.
+
+### Notifications
+
+There's a new `pleroma:chat_mention` notification, which has this form. It is not given out in the notifications endpoint by default, you need to explicitly request it with `include_types[]=pleroma:chat_mention`:
+
+```json
+{
+  "id": "someid",
+  "type": "pleroma:chat_mention",
+  "account": { ... } // User account of the sender,
+  "chat_message": {
+    "chat_id": "1",
+    "id": "10",
+    "content": "Hello",
+    "account_id": "someflakeid",
+    "unread": false
+  },
+  "created_at": "somedate"
+}
+```
+
+### Streaming
+
+There is an additional `user:pleroma_chat` stream. Incoming chat messages will make the current chat be sent to this `user` stream. The `event` of an incoming chat message is `pleroma:chat_update`. The payload is the updated chat with the incoming chat message in the `last_message` field.
+
+### Web Push
+
+If you want to receive push messages for this type, you'll need to add the `pleroma:chat_mention` type to your alerts in the push subscription.
--- a/docs/API/differences_in_mastoapi_responses.md
+++ b/docs/API/differences_in_mastoapi_responses.md
@ -230,3 +230,7 @@ Has theses additional parameters (which are the same as in Pleroma-API):
 Has these additional fields under the `pleroma` object:

 - `unread_count`: contains number unread notifications
+
+## Streaming
+
+There is an additional `user:pleroma_chat` stream. Incoming chat messages will make the current chat be sent to this `user` stream. The `event` of an incoming chat message is `pleroma:chat_update`. The payload is the updated chat with the incoming chat message in the `last_message` field.
--- a/docs/ap_extensions.md
+++ b/docs/ap_extensions.md
@ -0,0 +1,35 @@
+# ChatMessages
+
+ChatMessages are the messages sent in 1-on-1 chats. They are similar to
+`Note`s, but the addresing is done by having a single AP actor in the `to`
+field. Addressing multiple actors is not allowed. These messages are always
+private, there is no public version of them. They are created with a `Create`
+activity.
+
+Example:
+
+```json
+{
+  "actor": "http://2hu.gensokyo/users/raymoo",
+  "id": "http://2hu.gensokyo/objects/1",
+  "object": {
+    "attributedTo": "http://2hu.gensokyo/users/raymoo",
+    "content": "You expected a cute girl? Too bad.",
+    "id": "http://2hu.gensokyo/objects/2",
+    "published": "2020-02-12T14:08:20Z",
+    "to": [
+      "http://2hu.gensokyo/users/marisa"
+    ],
+    "type": "ChatMessage"
+  },
+  "published": "2018-02-12T14:08:20Z",
+  "to": [
+    "http://2hu.gensokyo/users/marisa"
+  ],
+  "type": "Create"
+}
+```
+
+This setup does not prevent multi-user chats, but these will have to go through
+a `Group`, which will be the recipient of the messages and then `Announce` them
+to the users in the `Group`.
--- a/lib/pleroma/activity.ex
+++ b/lib/pleroma/activity.ex
@ -24,16 +24,6 @@ defmodule Pleroma.Activity do

  @primary_key {:id, FlakeId.Ecto.CompatType, autogenerate: true}

-  # https://github.com/tootsuite/mastodon/blob/master/app/models/notification.rb#L19
-  @mastodon_notification_types %{
-    "Create" => "mention",
-    "Follow" => ["follow", "follow_request"],
-    "Announce" => "reblog",
-    "Like" => "favourite",
-    "Move" => "move",
-    "EmojiReact" => "pleroma:emoji_reaction"
-  }
-
  schema "activities" do
    field(:data, :map)
    field(:local, :boolean, default: true)
@ -300,32 +290,6 @@ def follow_accepted?(

  def follow_accepted?(_), do: false

-  @spec mastodon_notification_type(Activity.t()) :: String.t() | nil
-
-  for {ap_type, type} <- @mastodon_notification_types, not is_list(type) do
-    def mastodon_notification_type(%Activity{data: %{"type" => unquote(ap_type)}}),
-      do: unquote(type)
-  end
-
-  def mastodon_notification_type(%Activity{data: %{"type" => "Follow"}} = activity) do
-    if follow_accepted?(activity) do
-      "follow"
-    else
-      "follow_request"
-    end
-  end
-
-  def mastodon_notification_type(%Activity{}), do: nil
-
-  @spec from_mastodon_notification_type(String.t()) :: String.t() | nil
-  @doc "Converts Mastodon notification type to AR activity type"
-  def from_mastodon_notification_type(type) do
-    with {k, _v} <-
-           Enum.find(@mastodon_notification_types, fn {_k, v} -> type in List.wrap(v) end) do
-      k
-    end
-  end
-
  def all_by_actor_and_id(actor, status_ids \\ [])
  def all_by_actor_and_id(_actor, []), do: []

--- a/lib/pleroma/chat.ex
+++ b/lib/pleroma/chat.ex
@ -0,0 +1,72 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Chat do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias Pleroma.Repo
+  alias Pleroma.User
+
+  @moduledoc """
+  Chat keeps a reference to ChatMessage conversations between a user and an recipient. The recipient can be a user (for now) or a group (not implemented yet).
+
+  It is a helper only, to make it easy to display a list of chats with other people, ordered by last bump. The actual messages are retrieved by querying the recipients of the ChatMessages.
+  """
+
+  @primary_key {:id, FlakeId.Ecto.CompatType, autogenerate: true}
+
+  schema "chats" do
+    belongs_to(:user, User, type: FlakeId.Ecto.CompatType)
+    field(:recipient, :string)
+
+    timestamps()
+  end
+
+  def changeset(struct, params) do
+    struct
+    |> cast(params, [:user_id, :recipient])
+    |> validate_change(:recipient, fn
+      :recipient, recipient ->
+        case User.get_cached_by_ap_id(recipient) do
+          nil -> [recipient: "must be an existing user"]
+          _ -> []
+        end
+    end)
+    |> validate_required([:user_id, :recipient])
+    |> unique_constraint(:user_id, name: :chats_user_id_recipient_index)
+  end
+
+  def get_by_id(id) do
+    __MODULE__
+    |> Repo.get(id)
+  end
+
+  def get(user_id, recipient) do
+    __MODULE__
+    |> Repo.get_by(user_id: user_id, recipient: recipient)
+  end
+
+  def get_or_create(user_id, recipient) do
+    %__MODULE__{}
+    |> changeset(%{user_id: user_id, recipient: recipient})
+    |> Repo.insert(
+      # Need to set something, otherwise we get nothing back at all
+      on_conflict: [set: [recipient: recipient]],
+      returning: true,
+      conflict_target: [:user_id, :recipient]
+    )
+  end
+
+  def bump_or_create(user_id, recipient) do
+    %__MODULE__{}
+    |> changeset(%{user_id: user_id, recipient: recipient})
+    |> Repo.insert(
+      on_conflict: [set: [updated_at: NaiveDateTime.utc_now()]],
+      returning: true,
+      conflict_target: [:user_id, :recipient]
+    )
+  end
+end
--- a/lib/pleroma/chat/message_reference.ex
+++ b/lib/pleroma/chat/message_reference.ex
@ -0,0 +1,117 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Chat.MessageReference do
+  @moduledoc """
+  A reference that builds a relation between an AP chat message that a user can see and whether it has been seen
+  by them, or should be displayed to them. Used to build the chat view that is presented to the user.
+  """
+
+  use Ecto.Schema
+
+  alias Pleroma.Chat
+  alias Pleroma.Object
+  alias Pleroma.Repo
+
+  import Ecto.Changeset
+  import Ecto.Query
+
+  @primary_key {:id, FlakeId.Ecto.Type, autogenerate: true}
+
+  schema "chat_message_references" do
+    belongs_to(:object, Object)
+    belongs_to(:chat, Chat, type: FlakeId.Ecto.CompatType)
+
+    field(:unread, :boolean, default: true)
+
+    timestamps()
+  end
+
+  def changeset(struct, params) do
+    struct
+    |> cast(params, [:object_id, :chat_id, :unread])
+    |> validate_required([:object_id, :chat_id, :unread])
+  end
+
+  def get_by_id(id) do
+    __MODULE__
+    |> Repo.get(id)
+    |> Repo.preload(:object)
+  end
+
+  def delete(cm_ref) do
+    cm_ref
+    |> Repo.delete()
+  end
+
+  def delete_for_object(%{id: object_id}) do
+    from(cr in __MODULE__,
+      where: cr.object_id == ^object_id
+    )
+    |> Repo.delete_all()
+  end
+
+  def for_chat_and_object(%{id: chat_id}, %{id: object_id}) do
+    __MODULE__
+    |> Repo.get_by(chat_id: chat_id, object_id: object_id)
+    |> Repo.preload(:object)
+  end
+
+  def for_chat_query(chat) do
+    from(cr in __MODULE__,
+      where: cr.chat_id == ^chat.id,
+      order_by: [desc: :id],
+      preload: [:object]
+    )
+  end
+
+  def last_message_for_chat(chat) do
+    chat
+    |> for_chat_query()
+    |> limit(1)
+    |> Repo.one()
+  end
+
+  def create(chat, object, unread) do
+    params = %{
+      chat_id: chat.id,
+      object_id: object.id,
+      unread: unread
+    }
+
+    %__MODULE__{}
+    |> changeset(params)
+    |> Repo.insert()
+  end
+
+  def unread_count_for_chat(chat) do
+    chat
+    |> for_chat_query()
+    |> where([cmr], cmr.unread == true)
+    |> Repo.aggregate(:count)
+  end
+
+  def mark_as_read(cm_ref) do
+    cm_ref
+    |> changeset(%{unread: false})
+    |> Repo.update()
+  end
+
+  def set_all_seen_for_chat(chat, last_read_id \\ nil) do
+    query =
+      chat
+      |> for_chat_query()
+      |> exclude(:order_by)
+      |> exclude(:preload)
+      |> where([cmr], cmr.unread == true)
+
+    if last_read_id do
+      query
+      |> where([cmr], cmr.id <= ^last_read_id)
+    else
+      query
+    end
+    |> Repo.update_all(set: [unread: false])
+  end
+end
--- a/lib/pleroma/migration_helper/notification_backfill.ex
+++ b/lib/pleroma/migration_helper/notification_backfill.ex
@ -0,0 +1,85 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.MigrationHelper.NotificationBackfill do
+  alias Pleroma.Notification
+  alias Pleroma.Object
+  alias Pleroma.Repo
+  alias Pleroma.User
+
+  import Ecto.Query
+
+  def fill_in_notification_types do
+    query =
+      from(n in Pleroma.Notification,
+        where: is_nil(n.type),
+        preload: :activity
+      )
+
+    query
+    |> Repo.all()
+    |> Enum.each(fn notification ->
+      type =
+        notification.activity
+        |> type_from_activity()
+
+      notification
+      |> Notification.changeset(%{type: type})
+      |> Repo.update()
+    end)
+  end
+
+  # This is copied over from Notifications to keep this stable.
+  defp type_from_activity(%{data: %{"type" => type}} = activity) do
+    case type do
+      "Follow" ->
+        accepted_function = fn activity ->
+          with %User{} = follower <- User.get_by_ap_id(activity.data["actor"]),
+               %User{} = followed <- User.get_by_ap_id(activity.data["object"]) do
+            Pleroma.FollowingRelationship.following?(follower, followed)
+          end
+        end
+
+        if accepted_function.(activity) do
+          "follow"
+        else
+          "follow_request"
+        end
+
+      "Announce" ->
+        "reblog"
+
+      "Like" ->
+        "favourite"
+
+      "Move" ->
+        "move"
+
+      "EmojiReact" ->
+        "pleroma:emoji_reaction"
+
+      # Compatibility with old reactions
+      "EmojiReaction" ->
+        "pleroma:emoji_reaction"
+
+      "Create" ->
+        activity
+        |> type_from_activity_object()
+
+      t ->
+        raise "No notification type for activity type #{t}"
+    end
+  end
+
+  defp type_from_activity_object(%{data: %{"type" => "Create", "object" => %{}}}), do: "mention"
+
+  defp type_from_activity_object(%{data: %{"type" => "Create"}} = activity) do
+    object = Object.get_by_ap_id(activity.data["object"])
+
+    case object && object.data["type"] do
+      "ChatMessage" -> "pleroma:chat_mention"
+      _ -> "mention"
+    end
+  end
+end
--- a/lib/pleroma/notification.ex
+++ b/lib/pleroma/notification.ex
@ -30,12 +30,29 @@ defmodule Pleroma.Notification do

  schema "notifications" do
    field(:seen, :boolean, default: false)
+    # This is an enum type in the database. If you add a new notification type,
+    # remember to add a migration to add it to the `notifications_type` enum
+    # as well.
+    field(:type, :string)
    belongs_to(:user, User, type: FlakeId.Ecto.CompatType)
    belongs_to(:activity, Activity, type: FlakeId.Ecto.CompatType)

    timestamps()
  end

+  def update_notification_type(user, activity) do
+    with %__MODULE__{} = notification <-
+           Repo.get_by(__MODULE__, user_id: user.id, activity_id: activity.id) do
+      type =
+        activity
+        |> type_from_activity()
+
+      notification
+      |> changeset(%{type: type})
+      |> Repo.update()
+    end
+  end
+
  @spec unread_notifications_count(User.t()) :: integer()
  def unread_notifications_count(%User{id: user_id}) do
    from(q in __MODULE__,
@ -44,9 +61,21 @@ def unread_notifications_count(%User{id: user_id}) do
    |> Repo.aggregate(:count, :id)
  end

+  @notification_types ~w{
+    favourite
+    follow
+    follow_request
+    mention
+    move
+    pleroma:chat_mention
+    pleroma:emoji_reaction
+    reblog
+  }
+
  def changeset(%Notification{} = notification, attrs) do
    notification
-    |> cast(attrs, [:seen])
+    |> cast(attrs, [:seen, :type])
+    |> validate_inclusion(:type, @notification_types)
  end

  @spec last_read_query(User.t()) :: Ecto.Queryable.t()
@ -300,42 +329,95 @@ def dismiss(%{id: user_id} = _user, id) do
    end
  end

-  def create_notifications(%Activity{data: %{"to" => _, "type" => "Create"}} = activity) do
-    object = Object.normalize(activity)
+  def create_notifications(activity, options \\ [])
+
+  def create_notifications(%Activity{data: %{"to" => _, "type" => "Create"}} = activity, options) do
+    object = Object.normalize(activity, false)

    if object && object.data["type"] == "Answer" do
      {:ok, []}
    else
-      do_create_notifications(activity)
+      do_create_notifications(activity, options)
    end
  end

-  def create_notifications(%Activity{data: %{"type" => type}} = activity)
+  def create_notifications(%Activity{data: %{"type" => type}} = activity, options)
      when type in ["Follow", "Like", "Announce", "Move", "EmojiReact"] do
-    do_create_notifications(activity)
+    do_create_notifications(activity, options)
  end

-  def create_notifications(_), do: {:ok, []}
+  def create_notifications(_, _), do: {:ok, []}
+
+  defp do_create_notifications(%Activity{} = activity, options) do
+    do_send = Keyword.get(options, :do_send, true)

-  defp do_create_notifications(%Activity{} = activity) do
    {enabled_receivers, disabled_receivers} = get_notified_from_activity(activity)
    potential_receivers = enabled_receivers ++ disabled_receivers

    notifications =
      Enum.map(potential_receivers, fn user ->
-        do_send = user in enabled_receivers
+        do_send = do_send && user in enabled_receivers
        create_notification(activity, user, do_send)
      end)

    {:ok, notifications}
  end

+  defp type_from_activity(%{data: %{"type" => type}} = activity) do
+    case type do
+      "Follow" ->
+        if Activity.follow_accepted?(activity) do
+          "follow"
+        else
+          "follow_request"
+        end
+
+      "Announce" ->
+        "reblog"
+
+      "Like" ->
+        "favourite"
+
+      "Move" ->
+        "move"
+
+      "EmojiReact" ->
+        "pleroma:emoji_reaction"
+
+      # Compatibility with old reactions
+      "EmojiReaction" ->
+        "pleroma:emoji_reaction"
+
+      "Create" ->
+        activity
+        |> type_from_activity_object()
+
+      t ->
+        raise "No notification type for activity type #{t}"
+    end
+  end
+
+  defp type_from_activity_object(%{data: %{"type" => "Create", "object" => %{}}}), do: "mention"
+
+  defp type_from_activity_object(%{data: %{"type" => "Create"}} = activity) do
+    object = Object.get_by_ap_id(activity.data["object"])
+
+    case object && object.data["type"] do
+      "ChatMessage" -> "pleroma:chat_mention"
+      _ -> "mention"
+    end
+  end
+
  # TODO move to sql, too.
  def create_notification(%Activity{} = activity, %User{} = user, do_send \\ true) do
    unless skip?(activity, user) do
      {:ok, %{notification: notification}} =
        Multi.new()
-        |> Multi.insert(:notification, %Notification{user_id: user.id, activity: activity})
+        |> Multi.insert(:notification, %Notification{
+          user_id: user.id,
+          activity: activity,
+          type: type_from_activity(activity)
+        })
        |> Marker.multi_set_last_read_id(user, "notifications")
        |> Repo.transaction()

@ -527,4 +609,12 @@ def skip?(:recently_followed, %Activity{data: %{"type" => "Follow"}} = activity,
  end

  def skip?(_, _, _), do: false
+
+  def for_user_and_activity(user, activity) do
+    from(n in __MODULE__,
+      where: n.user_id == ^user.id,
+      where: n.activity_id == ^activity.id
+    )
+    |> Repo.one()
+  end
 end
--- a/lib/pleroma/upload.ex
+++ b/lib/pleroma/upload.ex
@ -67,6 +67,7 @@ def store(upload, opts \\ []) do
      {:ok,
       %{
         "type" => opts.activity_type,
+         "mediaType" => upload.content_type,
         "url" => [
           %{
             "type" => "Link",
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@ -112,7 +112,14 @@ defp increase_poll_votes_if_vote(%{

  defp increase_poll_votes_if_vote(_create_data), do: :noop

+  @object_types ["ChatMessage"]
  @spec persist(map(), keyword()) :: {:ok, Activity.t() | Object.t()}
+  def persist(%{"type" => type} = object, meta) when type in @object_types do
+    with {:ok, object} <- Object.create(object) do
+      {:ok, object, meta}
+    end
+  end
+
  def persist(object, meta) do
    with local <- Keyword.fetch!(meta, :local),
         {recipients, _, _} <- get_recipients(object),
@ -344,20 +351,21 @@ def update(%{to: to, cc: cc, actor: actor, object: object} = params) do
    end
  end

-  @spec follow(User.t(), User.t(), String.t() | nil, boolean()) ::
+  @spec follow(User.t(), User.t(), String.t() | nil, boolean(), keyword()) ::
          {:ok, Activity.t()} | {:error, any()}
-  def follow(follower, followed, activity_id \\ nil, local \\ true) do
+  def follow(follower, followed, activity_id \\ nil, local \\ true, opts \\ []) do
    with {:ok, result} <-
-           Repo.transaction(fn -> do_follow(follower, followed, activity_id, local) end) do
+           Repo.transaction(fn -> do_follow(follower, followed, activity_id, local, opts) end) do
      result
    end
  end

-  defp do_follow(follower, followed, activity_id, local) do
+  defp do_follow(follower, followed, activity_id, local, opts) do
+    skip_notify_and_stream = Keyword.get(opts, :skip_notify_and_stream, false)
    data = make_follow_data(follower, followed, activity_id)

    with {:ok, activity} <- insert(data, local),
-         _ <- notify_and_stream(activity),
+         _ <- skip_notify_and_stream || notify_and_stream(activity),
         :ok <- maybe_federate(activity) do
      {:ok, activity}
    else
@ -1000,6 +1008,18 @@ defp exclude_poll_votes(query, _) do
    end
  end

+  defp exclude_chat_messages(query, %{include_chat_messages: true}), do: query
+
+  defp exclude_chat_messages(query, _) do
+    if has_named_binding?(query, :object) do
+      from([activity, object: o] in query,
+        where: fragment("not(?->>'type' = ?)", o.data, "ChatMessage")
+      )
+    else
+      query
+    end
+  end
+
  defp exclude_invisible_actors(query, %{invisible_actors: true}), do: query

  defp exclude_invisible_actors(query, _opts) do
@ -1115,6 +1135,7 @@ def fetch_activities_query(recipients, opts \\ %{}) do
    |> restrict_instance(opts)
    |> Activity.restrict_deactivated_users()
    |> exclude_poll_votes(opts)
+    |> exclude_chat_messages(opts)
    |> exclude_invisible_actors(opts)
    |> exclude_visibility(opts)
  end
--- a/lib/pleroma/web/activity_pub/builder.ex
+++ b/lib/pleroma/web/activity_pub/builder.ex
@ -5,6 +5,7 @@ defmodule Pleroma.Web.ActivityPub.Builder do
  This module encodes our addressing policies and general shape of our objects.
  """

+  alias Pleroma.Emoji
  alias Pleroma.Object
  alias Pleroma.User
  alias Pleroma.Web.ActivityPub.Relay
@ -65,6 +66,42 @@ def delete(actor, object_id) do
     }, []}
  end

+  def create(actor, object, recipients) do
+    {:ok,
+     %{
+       "id" => Utils.generate_activity_id(),
+       "actor" => actor.ap_id,
+       "to" => recipients,
+       "object" => object,
+       "type" => "Create",
+       "published" => DateTime.utc_now() |> DateTime.to_iso8601()
+     }, []}
+  end
+
+  def chat_message(actor, recipient, content, opts \\ []) do
+    basic = %{
+      "id" => Utils.generate_object_id(),
+      "actor" => actor.ap_id,
+      "type" => "ChatMessage",
+      "to" => [recipient],
+      "content" => content,
+      "published" => DateTime.utc_now() |> DateTime.to_iso8601(),
+      "emoji" => Emoji.Formatter.get_emoji_map(content)
+    }
+
+    case opts[:attachment] do
+      %Object{data: attachment_data} ->
+        {
+          :ok,
+          Map.put(basic, "attachment", attachment_data),
+          []
+        }
+
+      _ ->
+        {:ok, basic, []}
+    end
+  end
+
  @spec tombstone(String.t(), String.t()) :: {:ok, map(), keyword()}
  def tombstone(actor, id) do
    {:ok,
--- a/lib/pleroma/web/activity_pub/object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validator.ex
@ -12,6 +12,8 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
  alias Pleroma.Object
  alias Pleroma.User
  alias Pleroma.Web.ActivityPub.ObjectValidators.AnnounceValidator
+  alias Pleroma.Web.ActivityPub.ObjectValidators.ChatMessageValidator
+  alias Pleroma.Web.ActivityPub.ObjectValidators.CreateChatMessageValidator
  alias Pleroma.Web.ActivityPub.ObjectValidators.DeleteValidator
  alias Pleroma.Web.ActivityPub.ObjectValidators.EmojiReactValidator
  alias Pleroma.Web.ActivityPub.ObjectValidators.LikeValidator
@ -43,8 +45,20 @@ def validate(%{"type" => "Delete"} = object, meta) do

  def validate(%{"type" => "Like"} = object, meta) do
    with {:ok, object} <-
-           object |> LikeValidator.cast_and_validate() |> Ecto.Changeset.apply_action(:insert) do
-      object = stringify_keys(object |> Map.from_struct())
+           object
+           |> LikeValidator.cast_and_validate()
+           |> Ecto.Changeset.apply_action(:insert) do
+      object = stringify_keys(object)
+      {:ok, object, meta}
+    end
+  end
+
+  def validate(%{"type" => "ChatMessage"} = object, meta) do
+    with {:ok, object} <-
+           object
+           |> ChatMessageValidator.cast_and_validate()
+           |> Ecto.Changeset.apply_action(:insert) do
+      object = stringify_keys(object)
      {:ok, object, meta}
    end
  end
@ -59,6 +73,18 @@ def validate(%{"type" => "EmojiReact"} = object, meta) do
    end
  end

+  def validate(%{"type" => "Create", "object" => object} = create_activity, meta) do
+    with {:ok, object_data} <- cast_and_apply(object),
+         meta = Keyword.put(meta, :object_data, object_data |> stringify_keys),
+         {:ok, create_activity} <-
+           create_activity
+           |> CreateChatMessageValidator.cast_and_validate(meta)
+           |> Ecto.Changeset.apply_action(:insert) do
+      create_activity = stringify_keys(create_activity)
+      {:ok, create_activity, meta}
+    end
+  end
+
  def validate(%{"type" => "Announce"} = object, meta) do
    with {:ok, object} <-
           object
@ -69,17 +95,30 @@ def validate(%{"type" => "Announce"} = object, meta) do
    end
  end

+  def cast_and_apply(%{"type" => "ChatMessage"} = object) do
+    ChatMessageValidator.cast_and_apply(object)
+  end
+
+  def cast_and_apply(o), do: {:error, {:validator_not_set, o}}
+
  def stringify_keys(%{__struct__: _} = object) do
    object
    |> Map.from_struct()
    |> stringify_keys
  end

-  def stringify_keys(object) do
+  def stringify_keys(object) when is_map(object) do
    object
-    |> Map.new(fn {key, val} -> {to_string(key), val} end)
+    |> Map.new(fn {key, val} -> {to_string(key), stringify_keys(val)} end)
  end

+  def stringify_keys(object) when is_list(object) do
+    object
+    |> Enum.map(&stringify_keys/1)
+  end
+
+  def stringify_keys(object), do: object
+
  def fetch_actor(object) do
    with {:ok, actor} <- Types.ObjectID.cast(object["actor"]) do
      User.get_or_fetch_by_ap_id(actor)
--- a/lib/pleroma/web/activity_pub/object_validators/attachment_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/attachment_validator.ex
@ -0,0 +1,80 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.AttachmentValidator do
+  use Ecto.Schema
+
+  alias Pleroma.Web.ActivityPub.ObjectValidators.UrlObjectValidator
+
+  import Ecto.Changeset
+
+  @primary_key false
+  embedded_schema do
+    field(:type, :string)
+    field(:mediaType, :string, default: "application/octet-stream")
+    field(:name, :string)
+
+    embeds_many(:url, UrlObjectValidator)
+  end
+
+  def cast_and_validate(data) do
+    data
+    |> cast_data()
+    |> validate_data()
+  end
+
+  def cast_data(data) do
+    %__MODULE__{}
+    |> changeset(data)
+  end
+
+  def changeset(struct, data) do
+    data =
+      data
+      |> fix_media_type()
+      |> fix_url()
+
+    struct
+    |> cast(data, [:type, :mediaType, :name])
+    |> cast_embed(:url, required: true)
+  end
+
+  def fix_media_type(data) do
+    data =
+      data
+      |> Map.put_new("mediaType", data["mimeType"])
+
+    if MIME.valid?(data["mediaType"]) do
+      data
+    else
+      data
+      |> Map.put("mediaType", "application/octet-stream")
+    end
+  end
+
+  def fix_url(data) do
+    case data["url"] do
+      url when is_binary(url) ->
+        data
+        |> Map.put(
+          "url",
+          [
+            %{
+              "href" => url,
+              "type" => "Link",
+              "mediaType" => data["mediaType"]
+            }
+          ]
+        )
+
+      _ ->
+        data
+    end
+  end
+
+  def validate_data(cng) do
+    cng
+    |> validate_required([:mediaType, :url, :type])
+  end
+end
--- a/lib/pleroma/web/activity_pub/object_validators/chat_message_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/chat_message_validator.ex
@ -0,0 +1,123 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.ChatMessageValidator do
+  use Ecto.Schema
+
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.ObjectValidators.AttachmentValidator
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types
+
+  import Ecto.Changeset
+  import Pleroma.Web.ActivityPub.Transmogrifier, only: [fix_emoji: 1]
+
+  @primary_key false
+  @derive Jason.Encoder
+
+  embedded_schema do
+    field(:id, Types.ObjectID, primary_key: true)
+    field(:to, Types.Recipients, default: [])
+    field(:type, :string)
+    field(:content, Types.SafeText)
+    field(:actor, Types.ObjectID)
+    field(:published, Types.DateTime)
+    field(:emoji, :map, default: %{})
+
+    embeds_one(:attachment, AttachmentValidator)
+  end
+
+  def cast_and_apply(data) do
+    data
+    |> cast_data
+    |> apply_action(:insert)
+  end
+
+  def cast_and_validate(data) do
+    data
+    |> cast_data()
+    |> validate_data()
+  end
+
+  def cast_data(data) do
+    %__MODULE__{}
+    |> changeset(data)
+  end
+
+  def fix(data) do
+    data
+    |> fix_emoji()
+    |> fix_attachment()
+    |> Map.put_new("actor", data["attributedTo"])
+  end
+
+  # Throws everything but the first one away
+  def fix_attachment(%{"attachment" => [attachment | _]} = data) do
+    data
+    |> Map.put("attachment", attachment)
+  end
+
+  def fix_attachment(data), do: data
+
+  def changeset(struct, data) do
+    data = fix(data)
+
+    struct
+    |> cast(data, List.delete(__schema__(:fields), :attachment))
+    |> cast_embed(:attachment)
+  end
+
+  def validate_data(data_cng) do
+    data_cng
+    |> validate_inclusion(:type, ["ChatMessage"])
+    |> validate_required([:id, :actor, :to, :type, :published])
+    |> validate_content_or_attachment()
+    |> validate_length(:to, is: 1)
+    |> validate_length(:content, max: Pleroma.Config.get([:instance, :remote_limit]))
+    |> validate_local_concern()
+  end
+
+  def validate_content_or_attachment(cng) do
+    attachment = get_field(cng, :attachment)
+
+    if attachment do
+      cng
+    else
+      cng
+      |> validate_required([:content])
+    end
+  end
+
+  @doc """
+  Validates the following
+  - If both users are in our system
+  - If at least one of the users in this ChatMessage is a local user
+  - If the recipient is not blocking the actor
+  """
+  def validate_local_concern(cng) do
+    with actor_ap <- get_field(cng, :actor),
+         {_, %User{} = actor} <- {:find_actor, User.get_cached_by_ap_id(actor_ap)},
+         {_, %User{} = recipient} <-
+           {:find_recipient, User.get_cached_by_ap_id(get_field(cng, :to) |> hd())},
+         {_, false} <- {:blocking_actor?, User.blocks?(recipient, actor)},
+         {_, true} <- {:local?, Enum.any?([actor, recipient], & &1.local)} do
+      cng
+    else
+      {:blocking_actor?, true} ->
+        cng
+        |> add_error(:actor, "actor is blocked by recipient")
+
+      {:local?, false} ->
+        cng
+        |> add_error(:actor, "actor and recipient are both remote")
+
+      {:find_actor, _} ->
+        cng
+        |> add_error(:actor, "can't find user")
+
+      {:find_recipient, _} ->
+        cng
+        |> add_error(:to, "can't find user")
+    end
+  end
+end
--- a/lib/pleroma/web/activity_pub/object_validators/create_chat_message_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/create_chat_message_validator.ex
@ -0,0 +1,91 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+# NOTES
+# - Can probably be a generic create validator
+# - doesn't embed, will only get the object id
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.CreateChatMessageValidator do
+  use Ecto.Schema
+
+  alias Pleroma.Object
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types
+
+  import Ecto.Changeset
+  import Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
+
+  @primary_key false
+
+  embedded_schema do
+    field(:id, Types.ObjectID, primary_key: true)
+    field(:actor, Types.ObjectID)
+    field(:type, :string)
+    field(:to, Types.Recipients, default: [])
+    field(:object, Types.ObjectID)
+  end
+
+  def cast_and_apply(data) do
+    data
+    |> cast_data
+    |> apply_action(:insert)
+  end
+
+  def cast_data(data) do
+    cast(%__MODULE__{}, data, __schema__(:fields))
+  end
+
+  def cast_and_validate(data, meta \\ []) do
+    cast_data(data)
+    |> validate_data(meta)
+  end
+
+  def validate_data(cng, meta \\ []) do
+    cng
+    |> validate_required([:id, :actor, :to, :type, :object])
+    |> validate_inclusion(:type, ["Create"])
+    |> validate_actor_presence()
+    |> validate_recipients_match(meta)
+    |> validate_actors_match(meta)
+    |> validate_object_nonexistence()
+  end
+
+  def validate_object_nonexistence(cng) do
+    cng
+    |> validate_change(:object, fn :object, object_id ->
+      if Object.get_cached_by_ap_id(object_id) do
+        [{:object, "The object to create already exists"}]
+      else
+        []
+      end
+    end)
+  end
+
+  def validate_actors_match(cng, meta) do
+    object_actor = meta[:object_data]["actor"]
+
+    cng
+    |> validate_change(:actor, fn :actor, actor ->
+      if actor == object_actor do
+        []
+      else
+        [{:actor, "Actor doesn't match with object actor"}]
+      end
+    end)
+  end
+
+  def validate_recipients_match(cng, meta) do
+    object_recipients = meta[:object_data]["to"] || []
+
+    cng
+    |> validate_change(:to, fn :to, recipients ->
+      activity_set = MapSet.new(recipients)
+      object_set = MapSet.new(object_recipients)
+
+      if MapSet.equal?(activity_set, object_set) do
+        []
+      else
+        [{:to, "Recipients don't match with object recipients"}]
+      end
+    end)
+  end
+end
--- a/lib/pleroma/web/activity_pub/object_validators/create_note_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/create_note_validator.ex
--- a/lib/pleroma/web/activity_pub/object_validators/delete_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/delete_validator.ex
@ -46,12 +46,13 @@ def add_deleted_activity_id(cng) do
    Answer
    Article
    Audio
+    ChatMessage
    Event
    Note
    Page
    Question
-    Video
    Tombstone
+    Video
  }
  def validate_data(cng) do
    cng
--- a/lib/pleroma/web/activity_pub/object_validators/types/recipients.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/types/recipients.ex
@ -11,11 +11,13 @@ def cast(object) when is_binary(object) do

  def cast(data) when is_list(data) do
    data
-    |> Enum.reduce({:ok, []}, fn element, acc ->
-      case {acc, ObjectID.cast(element)} do
-        {:error, _} -> :error
-        {_, :error} -> :error
-        {{:ok, list}, {:ok, id}} -> {:ok, [id | list]}
+    |> Enum.reduce_while({:ok, []}, fn element, {:ok, list} ->
+      case ObjectID.cast(element) do
+        {:ok, id} ->
+          {:cont, {:ok, [id | list]}}
+
+        _ ->
+          {:halt, :error}
      end
    end)
  end
--- a/lib/pleroma/web/activity_pub/object_validators/types/safe_text.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/types/safe_text.ex
@ -0,0 +1,25 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.Types.SafeText do
+  use Ecto.Type
+
+  alias Pleroma.HTML
+
+  def type, do: :string
+
+  def cast(str) when is_binary(str) do
+    {:ok, HTML.filter_tags(str)}
+  end
+
+  def cast(_), do: :error
+
+  def dump(data) do
+    {:ok, data}
+  end
+
+  def load(data) do
+    {:ok, data}
+  end
+end
--- a/lib/pleroma/web/activity_pub/object_validators/url_object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/url_object_validator.ex
@ -0,0 +1,20 @@
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.UrlObjectValidator do
+  use Ecto.Schema
+
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types
+
+  import Ecto.Changeset
+  @primary_key false
+
+  embedded_schema do
+    field(:type, :string)
+    field(:href, Types.Uri)
+    field(:mediaType, :string)
+  end
+
+  def changeset(struct, data) do
+    struct
+    |> cast(data, __schema__(:fields))
+    |> validate_required([:type, :href, :mediaType])
+  end
+end
--- a/lib/pleroma/web/activity_pub/pipeline.ex
+++ b/lib/pleroma/web/activity_pub/pipeline.ex
@ -17,6 +17,10 @@ defmodule Pleroma.Web.ActivityPub.Pipeline do
          {:ok, Activity.t() | Object.t(), keyword()} | {:error, any()}
  def common_pipeline(object, meta) do
    case Repo.transaction(fn -> do_common_pipeline(object, meta) end) do
+      {:ok, {:ok, activity, meta}} ->
+        SideEffects.handle_after_transaction(meta)
+        {:ok, activity, meta}
+
      {:ok, value} ->
        value

--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@ -6,12 +6,17 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
  collection, and so on.
  """
  alias Pleroma.Activity
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
  alias Pleroma.Notification
  alias Pleroma.Object
  alias Pleroma.Repo
  alias Pleroma.User
  alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.Web.ActivityPub.Pipeline
  alias Pleroma.Web.ActivityPub.Utils
+  alias Pleroma.Web.Push
+  alias Pleroma.Web.Streamer

  def handle(object, meta \\ [])

@ -27,6 +32,24 @@ def handle(%{data: %{"type" => "Like"}} = object, meta) do
    {:ok, object, meta}
  end

+  # Tasks this handles
+  # - Actually create object
+  # - Rollback if we couldn't create it
+  # - Set up notifications
+  def handle(%{data: %{"type" => "Create"}} = activity, meta) do
+    with {:ok, _object, meta} <- handle_object_creation(meta[:object_data], meta) do
+      {:ok, notifications} = Notification.create_notifications(activity, do_send: false)
+
+      meta =
+        meta
+        |> add_notifications(notifications)
+
+      {:ok, activity, meta}
+    else
+      e -> Repo.rollback(e)
+    end
+  end
+
  # Tasks this handles:
  # - Add announce to object
  # - Set up notification
@ -88,6 +111,8 @@ def handle(%{data: %{"type" => "Delete", "object" => deleted_object}} = object,
              Object.decrease_replies_count(in_reply_to)
            end

+            MessageReference.delete_for_object(deleted_object)
+
            ActivityPub.stream_out(object)
            ActivityPub.stream_out_participations(deleted_object, user)
            :ok
@ -112,6 +137,39 @@ def handle(object, meta) do
    {:ok, object, meta}
  end

+  def handle_object_creation(%{"type" => "ChatMessage"} = object, meta) do
+    with {:ok, object, meta} <- Pipeline.common_pipeline(object, meta) do
+      actor = User.get_cached_by_ap_id(object.data["actor"])
+      recipient = User.get_cached_by_ap_id(hd(object.data["to"]))
+
+      streamables =
+        [[actor, recipient], [recipient, actor]]
+        |> Enum.map(fn [user, other_user] ->
+          if user.local do
+            {:ok, chat} = Chat.bump_or_create(user.id, other_user.ap_id)
+            {:ok, cm_ref} = MessageReference.create(chat, object, user.ap_id != actor.ap_id)
+
+            {
+              ["user", "user:pleroma_chat"],
+              {user, %{cm_ref | chat: chat, object: object}}
+            }
+          end
+        end)
+        |> Enum.filter(& &1)
+
+      meta =
+        meta
+        |> add_streamables(streamables)
+
+      {:ok, object, meta}
+    end
+  end
+
+  # Nothing to do
+  def handle_object_creation(object) do
+    {:ok, object}
+  end
+
  def handle_undoing(%{data: %{"type" => "Like"}} = object) do
    with %Object{} = liked_object <- Object.get_by_ap_id(object.data["object"]),
         {:ok, _} <- Utils.remove_like_from_object(object, liked_object),
@ -148,4 +206,43 @@ def handle_undoing(
  end

  def handle_undoing(object), do: {:error, ["don't know how to handle", object]}
+
+  defp send_notifications(meta) do
+    Keyword.get(meta, :notifications, [])
+    |> Enum.each(fn notification ->
+      Streamer.stream(["user", "user:notification"], notification)
+      Push.send(notification)
+    end)
+
+    meta
+  end
+
+  defp send_streamables(meta) do
+    Keyword.get(meta, :streamables, [])
+    |> Enum.each(fn {topics, items} ->
+      Streamer.stream(topics, items)
+    end)
+
+    meta
+  end
+
+  defp add_streamables(meta, streamables) do
+    existing = Keyword.get(meta, :streamables, [])
+
+    meta
+    |> Keyword.put(:streamables, streamables ++ existing)
+  end
+
+  defp add_notifications(meta, notifications) do
+    existing = Keyword.get(meta, :notifications, [])
+
+    meta
+    |> Keyword.put(:notifications, notifications ++ existing)
+  end
+
+  def handle_after_transaction(meta) do
+    meta
+    |> send_notifications()
+    |> send_streamables()
+  end
 end
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@ -10,6 +10,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
  alias Pleroma.EarmarkRenderer
  alias Pleroma.FollowingRelationship
  alias Pleroma.Maps
+  alias Pleroma.Notification
  alias Pleroma.Object
  alias Pleroma.Object.Containment
  alias Pleroma.Repo
@ -527,7 +528,8 @@ def handle_incoming(
           User.get_cached_by_ap_id(Containment.get_actor(%{"actor" => followed})),
         {:ok, %User{} = follower} <-
           User.get_or_fetch_by_ap_id(Containment.get_actor(%{"actor" => follower})),
-         {:ok, activity} <- ActivityPub.follow(follower, followed, id, false) do
+         {:ok, activity} <-
+           ActivityPub.follow(follower, followed, id, false, skip_notify_and_stream: true) do
      with deny_follow_blocked <- Pleroma.Config.get([:user, :deny_follow_blocked]),
           {_, false} <- {:user_blocked, User.blocks?(followed, follower) && deny_follow_blocked},
           {_, false} <- {:user_locked, User.locked?(followed)},
@ -570,6 +572,7 @@ def handle_incoming(
          :noop
      end

+      ActivityPub.notify_and_stream(activity)
      {:ok, activity}
    else
      _e ->
@ -590,6 +593,8 @@ def handle_incoming(
      User.update_follower_count(followed)
      User.update_following_count(follower)

+      Notification.update_notification_type(followed, follow_activity)
+
      ActivityPub.accept(%{
        to: follow_activity.data["to"],
        type: "Accept",
@ -657,6 +662,16 @@ def handle_incoming(
    |> handle_incoming(options)
  end

+  def handle_incoming(
+        %{"type" => "Create", "object" => %{"type" => "ChatMessage"}} = data,
+        _options
+      ) do
+    with {:ok, %User{}} <- ObjectValidator.fetch_actor(data),
+         {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
+      {:ok, activity}
+    end
+  end
+
  def handle_incoming(%{"type" => type} = data, _options)
      when type in ["Like", "EmojiReact", "Announce"] do
    with :ok <- ObjectValidator.fetch_actor_and_object(data),
@ -1108,6 +1123,9 @@ def add_attributed_to(object) do
    Map.put(object, "attributedTo", attributed_to)
  end

+  # TODO: Revisit this
+  def prepare_attachments(%{"type" => "ChatMessage"} = object), do: object
+
  def prepare_attachments(object) do
    attachments =
      object
--- a/lib/pleroma/web/api_spec/operations/chat_operation.ex
+++ b/lib/pleroma/web/api_spec/operations/chat_operation.ex
@ -0,0 +1,355 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ApiSpec.ChatOperation do
+  alias OpenApiSpex.Operation
+  alias OpenApiSpex.Schema
+  alias Pleroma.Web.ApiSpec.Schemas.ApiError
+  alias Pleroma.Web.ApiSpec.Schemas.Chat
+  alias Pleroma.Web.ApiSpec.Schemas.ChatMessage
+
+  import Pleroma.Web.ApiSpec.Helpers
+
+  @spec open_api_operation(atom) :: Operation.t()
+  def open_api_operation(action) do
+    operation = String.to_existing_atom("#{action}_operation")
+    apply(__MODULE__, operation, [])
+  end
+
+  def mark_as_read_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "Mark all messages in the chat as read",
+      operationId: "ChatController.mark_as_read",
+      parameters: [Operation.parameter(:id, :path, :string, "The ID of the Chat")],
+      requestBody: request_body("Parameters", mark_as_read()),
+      responses: %{
+        200 =>
+          Operation.response(
+            "The updated chat",
+            "application/json",
+            Chat
+          )
+      },
+      security: [
+        %{
+          "oAuth" => ["write:chats"]
+        }
+      ]
+    }
+  end
+
+  def mark_message_as_read_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "Mark one message in the chat as read",
+      operationId: "ChatController.mark_message_as_read",
+      parameters: [
+        Operation.parameter(:id, :path, :string, "The ID of the Chat"),
+        Operation.parameter(:message_id, :path, :string, "The ID of the message")
+      ],
+      responses: %{
+        200 =>
+          Operation.response(
+            "The read ChatMessage",
+            "application/json",
+            ChatMessage
+          )
+      },
+      security: [
+        %{
+          "oAuth" => ["write:chats"]
+        }
+      ]
+    }
+  end
+
+  def show_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "Create a chat",
+      operationId: "ChatController.show",
+      parameters: [
+        Operation.parameter(
+          :id,
+          :path,
+          :string,
+          "The id of the chat",
+          required: true,
+          example: "1234"
+        )
+      ],
+      responses: %{
+        200 =>
+          Operation.response(
+            "The existing chat",
+            "application/json",
+            Chat
+          )
+      },
+      security: [
+        %{
+          "oAuth" => ["read"]
+        }
+      ]
+    }
+  end
+
+  def create_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "Create a chat",
+      operationId: "ChatController.create",
+      parameters: [
+        Operation.parameter(
+          :id,
+          :path,
+          :string,
+          "The account id of the recipient of this chat",
+          required: true,
+          example: "someflakeid"
+        )
+      ],
+      responses: %{
+        200 =>
+          Operation.response(
+            "The created or existing chat",
+            "application/json",
+            Chat
+          )
+      },
+      security: [
+        %{
+          "oAuth" => ["write:chats"]
+        }
+      ]
+    }
+  end
+
+  def index_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "Get a list of chats that you participated in",
+      operationId: "ChatController.index",
+      parameters: pagination_params(),
+      responses: %{
+        200 => Operation.response("The chats of the user", "application/json", chats_response())
+      },
+      security: [
+        %{
+          "oAuth" => ["read:chats"]
+        }
+      ]
+    }
+  end
+
+  def messages_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "Get the most recent messages of the chat",
+      operationId: "ChatController.messages",
+      parameters:
+        [Operation.parameter(:id, :path, :string, "The ID of the Chat")] ++
+          pagination_params(),
+      responses: %{
+        200 =>
+          Operation.response(
+            "The messages in the chat",
+            "application/json",
+            chat_messages_response()
+          )
+      },
+      security: [
+        %{
+          "oAuth" => ["read:chats"]
+        }
+      ]
+    }
+  end
+
+  def post_chat_message_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "Post a message to the chat",
+      operationId: "ChatController.post_chat_message",
+      parameters: [
+        Operation.parameter(:id, :path, :string, "The ID of the Chat")
+      ],
+      requestBody: request_body("Parameters", chat_message_create()),
+      responses: %{
+        200 =>
+          Operation.response(
+            "The newly created ChatMessage",
+            "application/json",
+            ChatMessage
+          ),
+        400 => Operation.response("Bad Request", "application/json", ApiError)
+      },
+      security: [
+        %{
+          "oAuth" => ["write:chats"]
+        }
+      ]
+    }
+  end
+
+  def delete_message_operation do
+    %Operation{
+      tags: ["chat"],
+      summary: "delete_message",
+      operationId: "ChatController.delete_message",
+      parameters: [
+        Operation.parameter(:id, :path, :string, "The ID of the Chat"),
+        Operation.parameter(:message_id, :path, :string, "The ID of the message")
+      ],
+      responses: %{
+        200 =>
+          Operation.response(
+            "The deleted ChatMessage",
+            "application/json",
+            ChatMessage
+          )
+      },
+      security: [
+        %{
+          "oAuth" => ["write:chats"]
+        }
+      ]
+    }
+  end
+
+  def chats_response do
+    %Schema{
+      title: "ChatsResponse",
+      description: "Response schema for multiple Chats",
+      type: :array,
+      items: Chat,
+      example: [
+        %{
+          "account" => %{
+            "pleroma" => %{
+              "is_admin" => false,
+              "confirmation_pending" => false,
+              "hide_followers_count" => false,
+              "is_moderator" => false,
+              "hide_favorites" => true,
+              "ap_id" => "https://dontbulling.me/users/lain",
+              "hide_follows_count" => false,
+              "hide_follows" => false,
+              "background_image" => nil,
+              "skip_thread_containment" => false,
+              "hide_followers" => false,
+              "relationship" => %{},
+              "tags" => []
+            },
+            "avatar" =>
+              "https://dontbulling.me/media/065a4dd3c6740dab13ff9c71ec7d240bb9f8be9205c9e7467fb2202117da1e32.jpg",
+            "following_count" => 0,
+            "header_static" => "https://originalpatchou.li/images/banner.png",
+            "source" => %{
+              "sensitive" => false,
+              "note" => "lain",
+              "pleroma" => %{
+                "discoverable" => false,
+                "actor_type" => "Person"
+              },
+              "fields" => []
+            },
+            "statuses_count" => 1,
+            "locked" => false,
+            "created_at" => "2020-04-16T13:40:15.000Z",
+            "display_name" => "lain",
+            "fields" => [],
+            "acct" => "lain@dontbulling.me",
+            "id" => "9u6Qw6TAZANpqokMkK",
+            "emojis" => [],
+            "avatar_static" =>
+              "https://dontbulling.me/media/065a4dd3c6740dab13ff9c71ec7d240bb9f8be9205c9e7467fb2202117da1e32.jpg",
+            "username" => "lain",
+            "followers_count" => 0,
+            "header" => "https://originalpatchou.li/images/banner.png",
+            "bot" => false,
+            "note" => "lain",
+            "url" => "https://dontbulling.me/users/lain"
+          },
+          "id" => "1",
+          "unread" => 2
+        }
+      ]
+    }
+  end
+
+  def chat_messages_response do
+    %Schema{
+      title: "ChatMessagesResponse",
+      description: "Response schema for multiple ChatMessages",
+      type: :array,
+      items: ChatMessage,
+      example: [
+        %{
+          "emojis" => [
+            %{
+              "static_url" => "https://dontbulling.me/emoji/Firefox.gif",
+              "visible_in_picker" => false,
+              "shortcode" => "firefox",
+              "url" => "https://dontbulling.me/emoji/Firefox.gif"
+            }
+          ],
+          "created_at" => "2020-04-21T15:11:46.000Z",
+          "content" => "Check this out :firefox:",
+          "id" => "13",
+          "chat_id" => "1",
+          "actor_id" => "someflakeid",
+          "unread" => false
+        },
+        %{
+          "actor_id" => "someflakeid",
+          "content" => "Whats' up?",
+          "id" => "12",
+          "chat_id" => "1",
+          "emojis" => [],
+          "created_at" => "2020-04-21T15:06:45.000Z",
+          "unread" => false
+        }
+      ]
+    }
+  end
+
+  def chat_message_create do
+    %Schema{
+      title: "ChatMessageCreateRequest",
+      description: "POST body for creating an chat message",
+      type: :object,
+      properties: %{
+        content: %Schema{
+          type: :string,
+          description: "The content of your message. Optional if media_id is present"
+        },
+        media_id: %Schema{type: :string, description: "The id of an upload"}
+      },
+      example: %{
+        "content" => "Hey wanna buy feet pics?",
+        "media_id" => "134234"
+      }
+    }
+  end
+
+  def mark_as_read do
+    %Schema{
+      title: "MarkAsReadRequest",
+      description: "POST body for marking a number of chat messages as read",
+      type: :object,
+      required: [:last_read_id],
+      properties: %{
+        last_read_id: %Schema{
+          type: :string,
+          description: "The content of your message."
+        }
+      },
+      example: %{
+        "last_read_id" => "abcdef12456"
+      }
+    }
+  end
+end
--- a/lib/pleroma/web/api_spec/operations/notification_operation.ex
+++ b/lib/pleroma/web/api_spec/operations/notification_operation.ex
@ -185,6 +185,7 @@ defp notification_type do
        "mention",
        "poll",
        "pleroma:emoji_reaction",
+        "pleroma:chat_mention",
        "move",
        "follow_request"
      ],
--- a/lib/pleroma/web/api_spec/operations/subscription_operation.ex
+++ b/lib/pleroma/web/api_spec/operations/subscription_operation.ex
@ -141,6 +141,11 @@ defp create_request do
                  allOf: [BooleanLike],
                  nullable: true,
                  description: "Receive poll notifications?"
+                },
+                "pleroma:chat_mention": %Schema{
+                  allOf: [BooleanLike],
+                  nullable: true,
+                  description: "Receive chat notifications?"
                }
              }
            }
--- a/lib/pleroma/web/api_spec/schemas/chat.ex
+++ b/lib/pleroma/web/api_spec/schemas/chat.ex
@ -0,0 +1,75 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ApiSpec.Schemas.Chat do
+  alias OpenApiSpex.Schema
+  alias Pleroma.Web.ApiSpec.Schemas.ChatMessage
+
+  require OpenApiSpex
+
+  OpenApiSpex.schema(%{
+    title: "Chat",
+    description: "Response schema for a Chat",
+    type: :object,
+    properties: %{
+      id: %Schema{type: :string},
+      account: %Schema{type: :object},
+      unread: %Schema{type: :integer},
+      last_message: ChatMessage,
+      updated_at: %Schema{type: :string, format: :"date-time"}
+    },
+    example: %{
+      "account" => %{
+        "pleroma" => %{
+          "is_admin" => false,
+          "confirmation_pending" => false,
+          "hide_followers_count" => false,
+          "is_moderator" => false,
+          "hide_favorites" => true,
+          "ap_id" => "https://dontbulling.me/users/lain",
+          "hide_follows_count" => false,
+          "hide_follows" => false,
+          "background_image" => nil,
+          "skip_thread_containment" => false,
+          "hide_followers" => false,
+          "relationship" => %{},
+          "tags" => []
+        },
+        "avatar" =>
+          "https://dontbulling.me/media/065a4dd3c6740dab13ff9c71ec7d240bb9f8be9205c9e7467fb2202117da1e32.jpg",
+        "following_count" => 0,
+        "header_static" => "https://originalpatchou.li/images/banner.png",
+        "source" => %{
+          "sensitive" => false,
+          "note" => "lain",
+          "pleroma" => %{
+            "discoverable" => false,
+            "actor_type" => "Person"
+          },
+          "fields" => []
+        },
+        "statuses_count" => 1,
+        "locked" => false,
+        "created_at" => "2020-04-16T13:40:15.000Z",
+        "display_name" => "lain",
+        "fields" => [],
+        "acct" => "lain@dontbulling.me",
+        "id" => "9u6Qw6TAZANpqokMkK",
+        "emojis" => [],
+        "avatar_static" =>
+          "https://dontbulling.me/media/065a4dd3c6740dab13ff9c71ec7d240bb9f8be9205c9e7467fb2202117da1e32.jpg",
+        "username" => "lain",
+        "followers_count" => 0,
+        "header" => "https://originalpatchou.li/images/banner.png",
+        "bot" => false,
+        "note" => "lain",
+        "url" => "https://dontbulling.me/users/lain"
+      },
+      "id" => "1",
+      "unread" => 2,
+      "last_message" => ChatMessage.schema().example(),
+      "updated_at" => "2020-04-21T15:06:45.000Z"
+    }
+  })
+end
--- a/lib/pleroma/web/api_spec/schemas/chat_message.ex
+++ b/lib/pleroma/web/api_spec/schemas/chat_message.ex
@ -0,0 +1,41 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ApiSpec.Schemas.ChatMessage do
+  alias OpenApiSpex.Schema
+
+  require OpenApiSpex
+
+  OpenApiSpex.schema(%{
+    title: "ChatMessage",
+    description: "Response schema for a ChatMessage",
+    nullable: true,
+    type: :object,
+    properties: %{
+      id: %Schema{type: :string},
+      account_id: %Schema{type: :string, description: "The Mastodon API id of the actor"},
+      chat_id: %Schema{type: :string},
+      content: %Schema{type: :string, nullable: true},
+      created_at: %Schema{type: :string, format: :"date-time"},
+      emojis: %Schema{type: :array},
+      attachment: %Schema{type: :object, nullable: true}
+    },
+    example: %{
+      "account_id" => "someflakeid",
+      "chat_id" => "1",
+      "content" => "hey you again",
+      "created_at" => "2020-04-21T15:06:45.000Z",
+      "emojis" => [
+        %{
+          "static_url" => "https://dontbulling.me/emoji/Firefox.gif",
+          "visible_in_picker" => false,
+          "shortcode" => "firefox",
+          "url" => "https://dontbulling.me/emoji/Firefox.gif"
+        }
+      ],
+      "id" => "14",
+      "attachment" => nil
+    }
+  })
+end
--- a/lib/pleroma/web/common_api/common_api.ex
+++ b/lib/pleroma/web/common_api/common_api.ex
@ -7,6 +7,7 @@ defmodule Pleroma.Web.CommonAPI do
  alias Pleroma.ActivityExpiration
  alias Pleroma.Conversation.Participation
  alias Pleroma.FollowingRelationship
+  alias Pleroma.Formatter
  alias Pleroma.Notification
  alias Pleroma.Object
  alias Pleroma.ThreadMute
@ -24,6 +25,53 @@ defmodule Pleroma.Web.CommonAPI do
  require Pleroma.Constants
  require Logger

+  def post_chat_message(%User{} = user, %User{} = recipient, content, opts \\ []) do
+    with maybe_attachment <- opts[:media_id] && Object.get_by_id(opts[:media_id]),
+         :ok <- validate_chat_content_length(content, !!maybe_attachment),
+         {_, {:ok, chat_message_data, _meta}} <-
+           {:build_object,
+            Builder.chat_message(
+              user,
+              recipient.ap_id,
+              content |> format_chat_content,
+              attachment: maybe_attachment
+            )},
+         {_, {:ok, create_activity_data, _meta}} <-
+           {:build_create_activity, Builder.create(user, chat_message_data, [recipient.ap_id])},
+         {_, {:ok, %Activity{} = activity, _meta}} <-
+           {:common_pipeline,
+            Pipeline.common_pipeline(create_activity_data,
+              local: true
+            )} do
+      {:ok, activity}
+    end
+  end
+
+  defp format_chat_content(nil), do: nil
+
+  defp format_chat_content(content) do
+    {text, _, _} =
+      content
+      |> Formatter.html_escape("text/plain")
+      |> Formatter.linkify()
+      |> (fn {text, mentions, tags} ->
+            {String.replace(text, ~r/\r?\n/, "<br>"), mentions, tags}
+          end).()
+
+    text
+  end
+
+  defp validate_chat_content_length(_, true), do: :ok
+  defp validate_chat_content_length(nil, false), do: {:error, :no_content}
+
+  defp validate_chat_content_length(content, _) do
+    if String.length(content) <= Pleroma.Config.get([:instance, :chat_limit]) do
+      :ok
+    else
+      {:error, :content_too_long}
+    end
+  end
+
  def unblock(blocker, blocked) do
    with {_, %Activity{} = block} <- {:fetch_block, Utils.fetch_latest_block(blocker, blocked)},
         {:ok, unblock_data, _} <- Builder.undo(blocker, block),
@ -73,6 +121,7 @@ def accept_follow_request(follower, followed) do
             object: follow_activity.data["id"],
             type: "Accept"
           }) do
+      Notification.update_notification_type(followed, follow_activity)
      {:ok, follower}
    end
  end
@ -427,12 +476,13 @@ def remove_mute(user, activity) do
    {:ok, activity}
  end

-  def thread_muted?(%{id: nil} = _user, _activity), do: false
-
-  def thread_muted?(user, activity) do
-    ThreadMute.exists?(user.id, activity.data["context"])
+  def thread_muted?(%User{id: user_id}, %{data: %{"context" => context}})
+      when is_binary("context") do
+    ThreadMute.exists?(user_id, context)
  end

+  def thread_muted?(_, _), do: false
+
  def report(user, data) do
    with {:ok, account} <- get_reported_account(data.account_id),
         {:ok, {content_html, _, _}} <- make_report_content_html(data[:comment]),
--- a/lib/pleroma/web/common_api/utils.ex
+++ b/lib/pleroma/web/common_api/utils.ex
@ -429,7 +429,7 @@ def maybe_notify_mentioned_recipients(
        %Activity{data: %{"to" => _to, "type" => type} = data} = activity
      )
      when type == "Create" do
-    object = Object.normalize(activity)
+    object = Object.normalize(activity, false)

    object_data =
      cond do
--- a/lib/pleroma/web/mastodon_api/controllers/notification_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/notification_controller.ex
@ -42,8 +42,20 @@ def index(conn, %{account_id: account_id} = params) do
    end
  end

+  @default_notification_types ~w{
+    mention
+    follow
+    follow_request
+    reblog
+    favourite
+    move
+    pleroma:emoji_reaction
+  }
  def index(%{assigns: %{user: user}} = conn, params) do
-    params = Map.new(params, fn {k, v} -> {to_string(k), v} end)
+    params =
+      Map.new(params, fn {k, v} -> {to_string(k), v} end)
+      |> Map.put_new("include_types", @default_notification_types)
+
    notifications = MastodonAPI.get_notifications(user, params)

    conn
--- a/lib/pleroma/web/mastodon_api/controllers/search_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/search_controller.ex
@ -124,6 +124,7 @@ defp resource_search(:v1, "hashtags", query, _options) do
  defp prepare_tags(query, add_joined_tag \\ true) do
    tags =
      query
+      |> preprocess_uri_query()
      |> String.split(~r/[^#\w]+/u, trim: true)
      |> Enum.uniq_by(&String.downcase/1)

@ -147,6 +148,19 @@ defp prepare_tags(query, add_joined_tag \\ true) do
    end
  end

+  # If `query` is a URI, returns last component of its path, otherwise returns `query`
+  defp preprocess_uri_query(query) do
+    if query =~ ~r/https?:\/\// do
+      query
+      |> URI.parse()
+      |> Map.get(:path)
+      |> String.split("/")
+      |> Enum.at(-1)
+    else
+      query
+    end
+  end
+
  defp joined_tag(tags) do
    tags
    |> Enum.map(fn tag -> String.capitalize(tag) end)
--- a/lib/pleroma/web/mastodon_api/mastodon_api.ex
+++ b/lib/pleroma/web/mastodon_api/mastodon_api.ex
@ -6,7 +6,6 @@ defmodule Pleroma.Web.MastodonAPI.MastodonAPI do
  import Ecto.Query
  import Ecto.Changeset

-  alias Pleroma.Activity
  alias Pleroma.Notification
  alias Pleroma.Pagination
  alias Pleroma.ScheduledActivity
@ -82,15 +81,11 @@ defp cast_params(params) do
  end

  defp restrict(query, :include_types, %{include_types: mastodon_types = [_ | _]}) do
-    ap_types = convert_and_filter_mastodon_types(mastodon_types)
-
-    where(query, [q, a], fragment("? @> ARRAY[?->>'type']::varchar[]", ^ap_types, a.data))
+    where(query, [n], n.type in ^mastodon_types)
  end

  defp restrict(query, :exclude_types, %{exclude_types: mastodon_types = [_ | _]}) do
-    ap_types = convert_and_filter_mastodon_types(mastodon_types)
-
-    where(query, [q, a], not fragment("? @> ARRAY[?->>'type']::varchar[]", ^ap_types, a.data))
+    where(query, [n], n.type not in ^mastodon_types)
  end

  defp restrict(query, :account_ap_id, %{account_ap_id: account_ap_id}) do
@ -98,10 +93,4 @@ defp restrict(query, :account_ap_id, %{account_ap_id: account_ap_id}) do
  end

  defp restrict(query, _, _), do: query
-
-  defp convert_and_filter_mastodon_types(types) do
-    types
-    |> Enum.map(&Activity.from_mastodon_notification_type/1)
-    |> Enum.filter(& &1)
-  end
 end
--- a/lib/pleroma/web/mastodon_api/views/account_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/account_view.ex
@ -235,6 +235,7 @@ defp do_render("show.json", %{user: user} = opts) do

      # Pleroma extension
      pleroma: %{
+        ap_id: user.ap_id,
        confirmation_pending: user.confirmation_pending,
        tags: user.tags,
        hide_followers_count: user.hide_followers_count,
--- a/lib/pleroma/web/mastodon_api/views/instance_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/instance_view.ex
@ -69,7 +69,8 @@ def features do
      if Config.get([:instance, :safe_dm_mentions]) do
        "safe_dm_mentions"
      end,
-      "pleroma_emoji_reactions"
+      "pleroma_emoji_reactions",
+      "pleroma_chat_messages"
    ]
    |> Enum.filter(& &1)
  end
--- a/lib/pleroma/web/mastodon_api/views/notification_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/notification_view.ex
@ -6,26 +6,28 @@ defmodule Pleroma.Web.MastodonAPI.NotificationView do
  use Pleroma.Web, :view

  alias Pleroma.Activity
+  alias Pleroma.Chat.MessageReference
  alias Pleroma.Notification
+  alias Pleroma.Object
  alias Pleroma.User
  alias Pleroma.UserRelationship
  alias Pleroma.Web.CommonAPI
  alias Pleroma.Web.MastodonAPI.AccountView
  alias Pleroma.Web.MastodonAPI.NotificationView
  alias Pleroma.Web.MastodonAPI.StatusView
+  alias Pleroma.Web.PleromaAPI.Chat.MessageReferenceView
+
+  @parent_types ~w{Like Announce EmojiReact}

  def render("index.json", %{notifications: notifications, for: reading_user} = opts) do
    activities = Enum.map(notifications, & &1.activity)

    parent_activities =
      activities
-      |> Enum.filter(
-        &(Activity.mastodon_notification_type(&1) in [
-            "favourite",
-            "reblog",
-            "pleroma:emoji_reaction"
-          ])
-      )
+      |> Enum.filter(fn
+        %{data: %{"type" => type}} ->
+          type in @parent_types
+      end)
      |> Enum.map(& &1.data["object"])
      |> Activity.create_by_object_ap_id()
      |> Activity.with_preloaded_object(:left)
@ -42,7 +44,7 @@ def render("index.json", %{notifications: notifications, for: reading_user} = op
        true ->
          move_activities_targets =
            activities
-            |> Enum.filter(&(Activity.mastodon_notification_type(&1) == "move"))
+            |> Enum.filter(&(&1.data["type"] == "Move"))
            |> Enum.map(&User.get_cached_by_ap_id(&1.data["target"]))

          actors =
@ -79,8 +81,6 @@ def render(
      end
    end

-    mastodon_type = Activity.mastodon_notification_type(activity)
-
    # Note: :relationships contain user mutes (needed for :muted flag in :status)
    status_render_opts = %{relationships: opts[:relationships]}

@ -91,7 +91,7 @@ def render(
           ) do
      response = %{
        id: to_string(notification.id),
-        type: mastodon_type,
+        type: notification.type,
        created_at: CommonAPI.Utils.to_masto_date(notification.inserted_at),
        account: account,
        pleroma: %{
@ -99,7 +99,7 @@ def render(
        }
      }

-      case mastodon_type do
+      case notification.type do
        "mention" ->
          put_status(response, activity, reading_user, status_render_opts)

@ -117,6 +117,9 @@ def render(
          |> put_status(parent_activity_fn.(), reading_user, status_render_opts)
          |> put_emoji(activity)

+        "pleroma:chat_mention" ->
+          put_chat_message(response, activity, reading_user, status_render_opts)
+
        type when type in ["follow", "follow_request"] ->
          response

@ -132,6 +135,17 @@ defp put_emoji(response, activity) do
    Map.put(response, :emoji, activity.data["content"])
  end

+  defp put_chat_message(response, activity, reading_user, opts) do
+    object = Object.normalize(activity)
+    author = User.get_cached_by_ap_id(object.data["actor"])
+    chat = Pleroma.Chat.get(reading_user.id, author.ap_id)
+    cm_ref = MessageReference.for_chat_and_object(chat, object)
+    render_opts = Map.merge(opts, %{for: reading_user, chat_message_reference: cm_ref})
+    chat_message_render = MessageReferenceView.render("show.json", render_opts)
+
+    Map.put(response, :chat_message, chat_message_render)
+  end
+
  defp put_status(response, activity, reading_user, opts) do
    status_render_opts = Map.merge(opts, %{activity: activity, for: reading_user})
    status_render = StatusView.render("show.json", status_render_opts)
--- a/lib/pleroma/web/pleroma_api/controllers/chat_controller.ex
+++ b/lib/pleroma/web/pleroma_api/controllers/chat_controller.ex
@ -0,0 +1,174 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+defmodule Pleroma.Web.PleromaAPI.ChatController do
+  use Pleroma.Web, :controller
+
+  alias Pleroma.Activity
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
+  alias Pleroma.Object
+  alias Pleroma.Pagination
+  alias Pleroma.Plugs.OAuthScopesPlug
+  alias Pleroma.Repo
+  alias Pleroma.User
+  alias Pleroma.Web.CommonAPI
+  alias Pleroma.Web.PleromaAPI.Chat.MessageReferenceView
+  alias Pleroma.Web.PleromaAPI.ChatView
+
+  import Ecto.Query
+
+  action_fallback(Pleroma.Web.MastodonAPI.FallbackController)
+
+  plug(
+    OAuthScopesPlug,
+    %{scopes: ["write:chats"]}
+    when action in [
+           :post_chat_message,
+           :create,
+           :mark_as_read,
+           :mark_message_as_read,
+           :delete_message
+         ]
+  )
+
+  plug(
+    OAuthScopesPlug,
+    %{scopes: ["read:chats"]} when action in [:messages, :index, :show]
+  )
+
+  plug(OpenApiSpex.Plug.CastAndValidate, render_error: Pleroma.Web.ApiSpec.RenderError)
+
+  defdelegate open_api_operation(action), to: Pleroma.Web.ApiSpec.ChatOperation
+
+  def delete_message(%{assigns: %{user: %{id: user_id} = user}} = conn, %{
+        message_id: message_id,
+        id: chat_id
+      }) do
+    with %MessageReference{} = cm_ref <-
+           MessageReference.get_by_id(message_id),
+         ^chat_id <- cm_ref.chat_id |> to_string(),
+         %Chat{user_id: ^user_id} <- Chat.get_by_id(chat_id),
+         {:ok, _} <- remove_or_delete(cm_ref, user) do
+      conn
+      |> put_view(MessageReferenceView)
+      |> render("show.json", chat_message_reference: cm_ref)
+    else
+      _e ->
+        {:error, :could_not_delete}
+    end
+  end
+
+  defp remove_or_delete(
+         %{object: %{data: %{"actor" => actor, "id" => id}}},
+         %{ap_id: actor} = user
+       ) do
+    with %Activity{} = activity <- Activity.get_create_by_object_ap_id(id) do
+      CommonAPI.delete(activity.id, user)
+    end
+  end
+
+  defp remove_or_delete(cm_ref, _) do
+    cm_ref
+    |> MessageReference.delete()
+  end
+
+  def post_chat_message(
+        %{body_params: params, assigns: %{user: %{id: user_id} = user}} = conn,
+        %{
+          id: id
+        }
+      ) do
+    with %Chat{} = chat <- Repo.get_by(Chat, id: id, user_id: user_id),
+         %User{} = recipient <- User.get_cached_by_ap_id(chat.recipient),
+         {:ok, activity} <-
+           CommonAPI.post_chat_message(user, recipient, params[:content],
+             media_id: params[:media_id]
+           ),
+         message <- Object.normalize(activity, false),
+         cm_ref <- MessageReference.for_chat_and_object(chat, message) do
+      conn
+      |> put_view(MessageReferenceView)
+      |> render("show.json", for: user, chat_message_reference: cm_ref)
+    end
+  end
+
+  def mark_message_as_read(%{assigns: %{user: %{id: user_id} = user}} = conn, %{
+        id: chat_id,
+        message_id: message_id
+      }) do
+    with %MessageReference{} = cm_ref <-
+           MessageReference.get_by_id(message_id),
+         ^chat_id <- cm_ref.chat_id |> to_string(),
+         %Chat{user_id: ^user_id} <- Chat.get_by_id(chat_id),
+         {:ok, cm_ref} <- MessageReference.mark_as_read(cm_ref) do
+      conn
+      |> put_view(MessageReferenceView)
+      |> render("show.json", for: user, chat_message_reference: cm_ref)
+    end
+  end
+
+  def mark_as_read(
+        %{body_params: %{last_read_id: last_read_id}, assigns: %{user: %{id: user_id}}} = conn,
+        %{id: id}
+      ) do
+    with %Chat{} = chat <- Repo.get_by(Chat, id: id, user_id: user_id),
+         {_n, _} <-
+           MessageReference.set_all_seen_for_chat(chat, last_read_id) do
+      conn
+      |> put_view(ChatView)
+      |> render("show.json", chat: chat)
+    end
+  end
+
+  def messages(%{assigns: %{user: %{id: user_id} = user}} = conn, %{id: id} = params) do
+    with %Chat{} = chat <- Repo.get_by(Chat, id: id, user_id: user_id) do
+      cm_refs =
+        chat
+        |> MessageReference.for_chat_query()
+        |> Pagination.fetch_paginated(params)
+
+      conn
+      |> put_view(MessageReferenceView)
+      |> render("index.json", for: user, chat_message_references: cm_refs)
+    else
+      _ ->
+        conn
+        |> put_status(:not_found)
+        |> json(%{error: "not found"})
+    end
+  end
+
+  def index(%{assigns: %{user: %{id: user_id} = user}} = conn, _params) do
+    blocked_ap_ids = User.blocked_users_ap_ids(user)
+
+    chats =
+      from(c in Chat,
+        where: c.user_id == ^user_id,
+        where: c.recipient not in ^blocked_ap_ids,
+        order_by: [desc: c.updated_at]
+      )
+      |> Repo.all()
+
+    conn
+    |> put_view(ChatView)
+    |> render("index.json", chats: chats)
+  end
+
+  def create(%{assigns: %{user: user}} = conn, params) do
+    with %User{ap_id: recipient} <- User.get_by_id(params[:id]),
+         {:ok, %Chat{} = chat} <- Chat.get_or_create(user.id, recipient) do
+      conn
+      |> put_view(ChatView)
+      |> render("show.json", chat: chat)
+    end
+  end
+
+  def show(%{assigns: %{user: user}} = conn, params) do
+    with %Chat{} = chat <- Repo.get_by(Chat, user_id: user.id, id: params[:id]) do
+      conn
+      |> put_view(ChatView)
+      |> render("show.json", chat: chat)
+    end
+  end
+end
--- a/lib/pleroma/web/pleroma_api/views/chat/message_reference_view.ex
+++ b/lib/pleroma/web/pleroma_api/views/chat/message_reference_view.ex
@ -0,0 +1,45 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.PleromaAPI.Chat.MessageReferenceView do
+  use Pleroma.Web, :view
+
+  alias Pleroma.User
+  alias Pleroma.Web.CommonAPI.Utils
+  alias Pleroma.Web.MastodonAPI.StatusView
+
+  def render(
+        "show.json",
+        %{
+          chat_message_reference: %{
+            id: id,
+            object: %{data: chat_message},
+            chat_id: chat_id,
+            unread: unread
+          }
+        }
+      ) do
+    %{
+      id: id |> to_string(),
+      content: chat_message["content"],
+      chat_id: chat_id |> to_string(),
+      account_id: User.get_cached_by_ap_id(chat_message["actor"]).id,
+      created_at: Utils.to_masto_date(chat_message["published"]),
+      emojis: StatusView.build_emojis(chat_message["emoji"]),
+      attachment:
+        chat_message["attachment"] &&
+          StatusView.render("attachment.json", attachment: chat_message["attachment"]),
+      unread: unread
+    }
+  end
+
+  def render("index.json", opts) do
+    render_many(
+      opts[:chat_message_references],
+      __MODULE__,
+      "show.json",
+      Map.put(opts, :as, :chat_message_reference)
+    )
+  end
+end
--- a/lib/pleroma/web/pleroma_api/views/chat_view.ex
+++ b/lib/pleroma/web/pleroma_api/views/chat_view.ex
@ -0,0 +1,33 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.PleromaAPI.ChatView do
+  use Pleroma.Web, :view
+
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
+  alias Pleroma.User
+  alias Pleroma.Web.CommonAPI.Utils
+  alias Pleroma.Web.MastodonAPI.AccountView
+  alias Pleroma.Web.PleromaAPI.Chat.MessageReferenceView
+
+  def render("show.json", %{chat: %Chat{} = chat} = opts) do
+    recipient = User.get_cached_by_ap_id(chat.recipient)
+    last_message = opts[:last_message] || MessageReference.last_message_for_chat(chat)
+
+    %{
+      id: chat.id |> to_string(),
+      account: AccountView.render("show.json", Map.put(opts, :user, recipient)),
+      unread: MessageReference.unread_count_for_chat(chat),
+      last_message:
+        last_message &&
+          MessageReferenceView.render("show.json", chat_message_reference: last_message),
+      updated_at: Utils.to_masto_date(chat.updated_at)
+    }
+  end
+
+  def render("index.json", %{chats: chats}) do
+    render_many(chats, __MODULE__, "show.json")
+  end
+end
--- a/lib/pleroma/web/push/impl.ex
+++ b/lib/pleroma/web/push/impl.ex
@ -16,8 +16,6 @@ defmodule Pleroma.Web.Push.Impl do
  require Logger
  import Ecto.Query

-  defdelegate mastodon_notification_type(activity), to: Activity
-
  @types ["Create", "Follow", "Announce", "Like", "Move"]

  @doc "Performs sending notifications for user subscriptions"
@ -31,10 +29,10 @@ def perform(
      when activity_type in @types do
    actor = User.get_cached_by_ap_id(notification.activity.data["actor"])

-    mastodon_type = mastodon_notification_type(notification.activity)
+    mastodon_type = notification.type
    gcm_api_key = Application.get_env(:web_push_encryption, :gcm_api_key)
    avatar_url = User.avatar_url(actor)
-    object = Object.normalize(activity)
+    object = Object.normalize(activity, false)
    user = User.get_cached_by_id(user_id)
    direct_conversation_id = Activity.direct_conversation_id(activity, user)

@ -116,7 +114,7 @@ def build_content(
  end

  def build_content(notification, actor, object, mastodon_type) do
-    mastodon_type = mastodon_type || mastodon_notification_type(notification.activity)
+    mastodon_type = mastodon_type || notification.type

    %{
      title: format_title(notification, mastodon_type),
@ -126,6 +124,13 @@ def build_content(notification, actor, object, mastodon_type) do

  def format_body(activity, actor, object, mastodon_type \\ nil)

+  def format_body(_activity, actor, %{data: %{"type" => "ChatMessage", "content" => content}}, _) do
+    case content do
+      nil -> "@#{actor.nickname}: (Attachment)"
+      content -> "@#{actor.nickname}: #{Utils.scrub_html_and_truncate(content, 80)}"
+    end
+  end
+
  def format_body(
        %{activity: %{data: %{"type" => "Create"}}},
        actor,
@ -151,7 +156,7 @@ def format_body(
        mastodon_type
      )
      when type in ["Follow", "Like"] do
-    mastodon_type = mastodon_type || mastodon_notification_type(notification.activity)
+    mastodon_type = mastodon_type || notification.type

    case mastodon_type do
      "follow" -> "@#{actor.nickname} has followed you"
@ -166,15 +171,14 @@ def format_title(%{activity: %{data: %{"directMessage" => true}}}, _mastodon_typ
    "New Direct Message"
  end

-  def format_title(%{activity: activity}, mastodon_type) do
-    mastodon_type = mastodon_type || mastodon_notification_type(activity)
-
-    case mastodon_type do
+  def format_title(%{type: type}, mastodon_type) do
+    case mastodon_type || type do
      "mention" -> "New Mention"
      "follow" -> "New Follower"
      "follow_request" -> "New Follow Request"
      "reblog" -> "New Repeat"
      "favourite" -> "New Favorite"
+      "pleroma:chat_mention" -> "New Chat Message"
      type -> "New #{String.capitalize(type || "event")}"
    end
  end
--- a/lib/pleroma/web/push/subscription.ex
+++ b/lib/pleroma/web/push/subscription.ex
@ -25,7 +25,7 @@ defmodule Pleroma.Web.Push.Subscription do
    timestamps()
  end

-  @supported_alert_types ~w[follow favourite mention reblog]a
+  @supported_alert_types ~w[follow favourite mention reblog pleroma:chat_mention]a

  defp alerts(%{data: %{alerts: alerts}}) do
    alerts = Map.take(alerts, @supported_alert_types)
--- a/lib/pleroma/web/router.ex
+++ b/lib/pleroma/web/router.ex
@ -306,6 +306,15 @@ defmodule Pleroma.Web.Router do
    scope [] do
      pipe_through(:authenticated_api)

+      post("/chats/by-account-id/:id", ChatController, :create)
+      get("/chats", ChatController, :index)
+      get("/chats/:id", ChatController, :show)
+      get("/chats/:id/messages", ChatController, :messages)
+      post("/chats/:id/messages", ChatController, :post_chat_message)
+      delete("/chats/:id/messages/:message_id", ChatController, :delete_message)
+      post("/chats/:id/read", ChatController, :mark_as_read)
+      post("/chats/:id/messages/:message_id/read", ChatController, :mark_message_as_read)
+
      get("/conversations/:id/statuses", ConversationController, :statuses)
      get("/conversations/:id", ConversationController, :show)
      post("/conversations/read", ConversationController, :mark_as_read)
--- a/lib/pleroma/web/streamer/streamer.ex
+++ b/lib/pleroma/web/streamer/streamer.ex
@ -6,6 +6,7 @@ defmodule Pleroma.Web.Streamer do
  require Logger

  alias Pleroma.Activity
+  alias Pleroma.Chat.MessageReference
  alias Pleroma.Config
  alias Pleroma.Conversation.Participation
  alias Pleroma.Notification
@ -22,7 +23,7 @@ defmodule Pleroma.Web.Streamer do
  def registry, do: @registry

  @public_streams ["public", "public:local", "public:media", "public:local:media"]
-  @user_streams ["user", "user:notification", "direct"]
+  @user_streams ["user", "user:notification", "direct", "user:pleroma_chat"]

  @doc "Expands and authorizes a stream, and registers the process for streaming."
  @spec get_topic_and_add_socket(stream :: String.t(), User.t() | nil, Map.t() | nil) ::
@ -89,29 +90,15 @@ def remove_socket(topic) do
    if should_env_send?(), do: Registry.unregister(@registry, topic)
  end

-  def stream(topics, item) when is_list(topics) do
-    if should_env_send?() do
-      Enum.each(topics, fn t ->
-        spawn(fn -> do_stream(t, item) end)
-      end)
-    end
-
-    :ok
-  end
-
-  def stream(topic, items) when is_list(items) do
-    if should_env_send?() do
-      Enum.each(items, fn i ->
-        spawn(fn -> do_stream(topic, i) end)
-      end)
-
-      :ok
-    end
-  end
-
-  def stream(topic, item) do
+  def stream(topics, items) do
    if should_env_send?() do
+      List.wrap(topics)
+      |> Enum.each(fn topic ->
+        List.wrap(items)
+        |> Enum.each(fn item ->
          spawn(fn -> do_stream(topic, item) end)
+        end)
+      end)
    end

    :ok
@ -200,6 +187,19 @@ defp do_stream(topic, %Notification{} = item)
    end)
  end

+  defp do_stream(topic, {user, %MessageReference{} = cm_ref})
+       when topic in ["user", "user:pleroma_chat"] do
+    topic = "#{topic}:#{user.id}"
+
+    text = StreamerView.render("chat_update.json", %{chat_message_reference: cm_ref})
+
+    Registry.dispatch(@registry, topic, fn list ->
+      Enum.each(list, fn {pid, _auth} ->
+        send(pid, {:text, text})
+      end)
+    end)
+  end
+
  defp do_stream("user", item) do
    Logger.debug("Trying to push to users")

--- a/lib/pleroma/web/views/streamer_view.ex
+++ b/lib/pleroma/web/views/streamer_view.ex
@ -51,6 +51,29 @@ def render("update.json", %Activity{} = activity) do
    |> Jason.encode!()
  end

+  def render("chat_update.json", %{chat_message_reference: cm_ref}) do
+    # Explicitly giving the cmr for the object here, so we don't accidentally
+    # send a later 'last_message' that was inserted between inserting this and
+    # streaming it out
+    #
+    # It also contains the chat with a cache of the correct unread count
+    Logger.debug("Trying to stream out #{inspect(cm_ref)}")
+
+    representation =
+      Pleroma.Web.PleromaAPI.ChatView.render(
+        "show.json",
+        %{last_message: cm_ref, chat: cm_ref.chat}
+      )
+
+    %{
+      event: "pleroma:chat_update",
+      payload:
+        representation
+        |> Jason.encode!()
+    }
+    |> Jason.encode!()
+  end
+
  def render("conversation.json", %Participation{} = participation) do
    %{
      event: "conversation",
--- a/priv/repo/migrations/20200309123730_create_chats.exs
+++ b/priv/repo/migrations/20200309123730_create_chats.exs
@ -0,0 +1,16 @@
+defmodule Pleroma.Repo.Migrations.CreateChats do
+  use Ecto.Migration
+
+  def change do
+    create table(:chats) do
+      add(:user_id, references(:users, type: :uuid))
+      # Recipient is an ActivityPub id, to future-proof for group support.
+      add(:recipient, :string)
+      add(:unread, :integer, default: 0)
+      timestamps()
+    end
+
+    # There's only one chat between a user and a recipient.
+    create(index(:chats, [:user_id, :recipient], unique: true))
+  end
+end
--- a/priv/repo/migrations/20200602094828_add_type_to_notifications.exs
+++ b/priv/repo/migrations/20200602094828_add_type_to_notifications.exs
@ -0,0 +1,9 @@
+defmodule Pleroma.Repo.Migrations.AddTypeToNotifications do
+  use Ecto.Migration
+
+  def change do
+    alter table(:notifications) do
+      add(:type, :string)
+    end
+  end
+end
--- a/priv/repo/migrations/20200602125218_backfill_notification_types.exs
+++ b/priv/repo/migrations/20200602125218_backfill_notification_types.exs
@ -0,0 +1,10 @@
+defmodule Pleroma.Repo.Migrations.BackfillNotificationTypes do
+  use Ecto.Migration
+
+  def up do
+    Pleroma.MigrationHelper.NotificationBackfill.fill_in_notification_types()
+  end
+
+  def down do
+  end
+end
--- a/priv/repo/migrations/20200602150528_create_chat_message_reference.exs
+++ b/priv/repo/migrations/20200602150528_create_chat_message_reference.exs
@ -0,0 +1,20 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Repo.Migrations.CreateChatMessageReference do
+  use Ecto.Migration
+
+  def change do
+    create table(:chat_message_references, primary_key: false) do
+      add(:id, :uuid, primary_key: true)
+      add(:chat_id, references(:chats, on_delete: :delete_all), null: false)
+      add(:object_id, references(:objects, on_delete: :delete_all), null: false)
+      add(:seen, :boolean, default: false, null: false)
+
+      timestamps()
+    end
+
+    create(index(:chat_message_references, [:chat_id, "id desc"]))
+  end
+end
--- a/priv/repo/migrations/20200603105113_add_unique_index_to_chat_message_references.exs
+++ b/priv/repo/migrations/20200603105113_add_unique_index_to_chat_message_references.exs
@ -0,0 +1,7 @@
+defmodule Pleroma.Repo.Migrations.AddUniqueIndexToChatMessageReferences do
+  use Ecto.Migration
+
+  def change do
+    create(unique_index(:chat_message_references, [:object_id, :chat_id]))
+  end
+end
--- a/priv/repo/migrations/20200603120448_remove_unread_from_chats.exs
+++ b/priv/repo/migrations/20200603120448_remove_unread_from_chats.exs
@ -0,0 +1,9 @@
+defmodule Pleroma.Repo.Migrations.RemoveUnreadFromChats do
+  use Ecto.Migration
+
+  def change do
+    alter table(:chats) do
+      remove(:unread, :integer, default: 0)
+    end
+  end
+end
--- a/priv/repo/migrations/20200603122732_add_seen_index_to_chat_message_references.exs
+++ b/priv/repo/migrations/20200603122732_add_seen_index_to_chat_message_references.exs
@ -0,0 +1,12 @@
+defmodule Pleroma.Repo.Migrations.AddSeenIndexToChatMessageReferences do
+  use Ecto.Migration
+
+  def change do
+    create(
+      index(:chat_message_references, [:chat_id],
+        where: "seen = false",
+        name: "unseen_messages_count_index"
+      )
+    )
+  end
+end
--- a/priv/repo/migrations/20200604150318_migrate_seen_to_unread_in_chat_message_references.exs
+++ b/priv/repo/migrations/20200604150318_migrate_seen_to_unread_in_chat_message_references.exs
@ -0,0 +1,30 @@
+defmodule Pleroma.Repo.Migrations.MigrateSeenToUnreadInChatMessageReferences do
+  use Ecto.Migration
+
+  def change do
+    drop(
+      index(:chat_message_references, [:chat_id],
+        where: "seen = false",
+        name: "unseen_messages_count_index"
+      )
+    )
+
+    alter table(:chat_message_references) do
+      add(:unread, :boolean, default: true)
+    end
+
+    execute("update chat_message_references set unread = not seen")
+
+    alter table(:chat_message_references) do
+      modify(:unread, :boolean, default: true, null: false)
+      remove(:seen, :boolean, default: false, null: false)
+    end
+
+    create(
+      index(:chat_message_references, [:chat_id],
+        where: "unread = true",
+        name: "unread_messages_count_index"
+      )
+    )
+  end
+end
--- a/priv/repo/migrations/20200606105430_change_type_to_enum_for_notifications.exs
+++ b/priv/repo/migrations/20200606105430_change_type_to_enum_for_notifications.exs
@ -0,0 +1,36 @@
+defmodule Pleroma.Repo.Migrations.ChangeTypeToEnumForNotifications do
+  use Ecto.Migration
+
+  def up do
+    """
+    create type notification_type as enum (
+      'follow',
+      'follow_request',
+      'mention',
+      'move',
+      'pleroma:emoji_reaction',
+      'pleroma:chat_mention',
+      'reblog',
+      'favourite'
+    )
+    """
+    |> execute()
+
+    """
+    alter table notifications 
+    alter column type type notification_type using (type::notification_type)
+    """
+    |> execute()
+  end
+
+  def down do
+    alter table(:notifications) do
+      modify(:type, :string)
+    end
+
+    """
+    drop type notification_type
+    """
+    |> execute()
+  end
+end
--- a/priv/repo/migrations/20200607112923_change_chat_id_to_flake.exs
+++ b/priv/repo/migrations/20200607112923_change_chat_id_to_flake.exs
@ -0,0 +1,23 @@
+defmodule Pleroma.Repo.Migrations.ChangeChatIdToFlake do
+  use Ecto.Migration
+
+  def up do
+    execute("""
+    alter table chats
+    drop constraint chats_pkey cascade,
+    alter column id drop default,
+    alter column id set data type uuid using cast( lpad( to_hex(id), 32, '0') as uuid),
+    add primary key (id)
+    """)
+
+    execute("""
+    alter table chat_message_references
+    alter column chat_id set data type uuid using cast( lpad( to_hex(chat_id), 32, '0') as uuid),
+    add constraint chat_message_references_chat_id_fkey foreign key (chat_id) references chats(id) on delete cascade
+    """)
+  end
+
+  def down do
+    :ok
+  end
+end
--- a/priv/static/schemas/litepub-0.1.jsonld
+++ b/priv/static/schemas/litepub-0.1.jsonld
@ -30,6 +30,7 @@
                "@type": "@id"
            },
            "EmojiReact": "litepub:EmojiReact",
+            "ChatMessage": "litepub:ChatMessage",
            "alsoKnownAs": {
                "@id": "as:alsoKnownAs",
                "@type": "@id"
--- a/test/chat/message_reference_test.exs
+++ b/test/chat/message_reference_test.exs
@ -0,0 +1,29 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Chat.MessageReferenceTest do
+  use Pleroma.DataCase, async: true
+
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
+  alias Pleroma.Web.CommonAPI
+
+  import Pleroma.Factory
+
+  describe "messages" do
+    test "it returns the last message in a chat" do
+      user = insert(:user)
+      recipient = insert(:user)
+
+      {:ok, _message_1} = CommonAPI.post_chat_message(user, recipient, "hey")
+      {:ok, _message_2} = CommonAPI.post_chat_message(recipient, user, "ho")
+
+      {:ok, chat} = Chat.get_or_create(user.id, recipient.ap_id)
+
+      message = MessageReference.last_message_for_chat(chat)
+
+      assert message.object.data["content"] == "ho"
+    end
+  end
+end
--- a/test/chat_test.exs
+++ b/test/chat_test.exs
@ -0,0 +1,61 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.ChatTest do
+  use Pleroma.DataCase, async: true
+
+  alias Pleroma.Chat
+
+  import Pleroma.Factory
+
+  describe "creation and getting" do
+    test "it only works if the recipient is a valid user (for now)" do
+      user = insert(:user)
+
+      assert {:error, _chat} = Chat.bump_or_create(user.id, "http://some/nonexisting/account")
+      assert {:error, _chat} = Chat.get_or_create(user.id, "http://some/nonexisting/account")
+    end
+
+    test "it creates a chat for a user and recipient" do
+      user = insert(:user)
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.bump_or_create(user.id, other_user.ap_id)
+
+      assert chat.id
+    end
+
+    test "it returns and bumps a chat for a user and recipient if it already exists" do
+      user = insert(:user)
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.bump_or_create(user.id, other_user.ap_id)
+      {:ok, chat_two} = Chat.bump_or_create(user.id, other_user.ap_id)
+
+      assert chat.id == chat_two.id
+    end
+
+    test "it returns a chat for a user and recipient if it already exists" do
+      user = insert(:user)
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.get_or_create(user.id, other_user.ap_id)
+      {:ok, chat_two} = Chat.get_or_create(user.id, other_user.ap_id)
+
+      assert chat.id == chat_two.id
+    end
+
+    test "a returning chat will have an updated `update_at` field" do
+      user = insert(:user)
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.bump_or_create(user.id, other_user.ap_id)
+      :timer.sleep(1500)
+      {:ok, chat_two} = Chat.bump_or_create(user.id, other_user.ap_id)
+
+      assert chat.id == chat_two.id
+      assert chat.updated_at != chat_two.updated_at
+    end
+  end
+end
--- a/test/fixtures/create-chat-message.json
+++ b/test/fixtures/create-chat-message.json
@ -0,0 +1,31 @@
+{
+  "actor": "http://2hu.gensokyo/users/raymoo",
+  "id": "http://2hu.gensokyo/objects/1",
+  "object": {
+    "attributedTo": "http://2hu.gensokyo/users/raymoo",
+    "content": "You expected a cute girl? Too bad. <script>alert('XSS')</script>",
+    "id": "http://2hu.gensokyo/objects/2",
+    "published": "2020-02-12T14:08:20Z",
+    "to": [
+      "http://2hu.gensokyo/users/marisa"
+    ],
+    "tag": [
+      {
+        "icon": {
+          "type": "Image",
+          "url": "http://2hu.gensokyo/emoji/Firefox.gif"
+        },
+        "id": "http://2hu.gensokyo/emoji/Firefox.gif",
+        "name": ":firefox:",
+        "type": "Emoji",
+        "updated": "1970-01-01T00:00:00Z"
+      }
+    ],
+    "type": "ChatMessage"
+  },
+  "published": "2018-02-12T14:08:20Z",
+  "to": [
+    "http://2hu.gensokyo/users/marisa"
+  ],
+  "type": "Create"
+}
--- a/test/migration_helper/notification_backfill_test.exs
+++ b/test/migration_helper/notification_backfill_test.exs
@ -0,0 +1,56 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.MigrationHelper.NotificationBackfillTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Activity
+  alias Pleroma.MigrationHelper.NotificationBackfill
+  alias Pleroma.Notification
+  alias Pleroma.Repo
+  alias Pleroma.Web.CommonAPI
+
+  import Pleroma.Factory
+
+  describe "fill_in_notification_types" do
+    test "it fills in missing notification types" do
+      user = insert(:user)
+      other_user = insert(:user)
+
+      {:ok, post} = CommonAPI.post(user, %{status: "yeah, @#{other_user.nickname}"})
+      {:ok, chat} = CommonAPI.post_chat_message(user, other_user, "yo")
+      {:ok, react} = CommonAPI.react_with_emoji(post.id, other_user, "☕")
+      {:ok, like} = CommonAPI.favorite(other_user, post.id)
+      {:ok, react_2} = CommonAPI.react_with_emoji(post.id, other_user, "☕")
+
+      data =
+        react_2.data
+        |> Map.put("type", "EmojiReaction")
+
+      {:ok, react_2} =
+        react_2
+        |> Activity.change(%{data: data})
+        |> Repo.update()
+
+      assert {5, nil} = Repo.update_all(Notification, set: [type: nil])
+
+      NotificationBackfill.fill_in_notification_types()
+
+      assert %{type: "mention"} =
+               Repo.get_by(Notification, user_id: other_user.id, activity_id: post.id)
+
+      assert %{type: "favourite"} =
+               Repo.get_by(Notification, user_id: user.id, activity_id: like.id)
+
+      assert %{type: "pleroma:emoji_reaction"} =
+               Repo.get_by(Notification, user_id: user.id, activity_id: react.id)
+
+      assert %{type: "pleroma:emoji_reaction"} =
+               Repo.get_by(Notification, user_id: user.id, activity_id: react_2.id)
+
+      assert %{type: "pleroma:chat_mention"} =
+               Repo.get_by(Notification, user_id: other_user.id, activity_id: chat.id)
+    end
+  end
+end
--- a/test/notification_test.exs
+++ b/test/notification_test.exs
@ -10,6 +10,7 @@ defmodule Pleroma.NotificationTest do

  alias Pleroma.FollowingRelationship
  alias Pleroma.Notification
+  alias Pleroma.Repo
  alias Pleroma.Tests.ObanHelpers
  alias Pleroma.User
  alias Pleroma.Web.ActivityPub.ActivityPub
@ -31,6 +32,7 @@ test "creates a notification for an emoji reaction" do
      {:ok, [notification]} = Notification.create_notifications(activity)

      assert notification.user_id == user.id
+      assert notification.type == "pleroma:emoji_reaction"
    end

    test "notifies someone when they are directly addressed" do
@ -48,6 +50,7 @@ test "notifies someone when they are directly addressed" do
      notified_ids = Enum.sort([notification.user_id, other_notification.user_id])
      assert notified_ids == [other_user.id, third_user.id]
      assert notification.activity_id == activity.id
+      assert notification.type == "mention"
      assert other_notification.activity_id == activity.id

      assert [%Pleroma.Marker{unread_count: 2}] =
@ -335,9 +338,12 @@ test "it creates `follow_request` notification for pending Follow activity" do
      # After request is accepted, the same notification is rendered with type "follow":
      assert {:ok, _} = CommonAPI.accept_follow_request(user, followed_user)

-      notification_id = notification.id
-      assert [%{id: ^notification_id}] = Notification.for_user(followed_user)
-      assert %{type: "follow"} = NotificationView.render("show.json", render_opts)
+      notification =
+        Repo.get(Notification, notification.id)
+        |> Repo.preload(:activity)
+
+      assert %{type: "follow"} =
+               NotificationView.render("show.json", notification: notification, for: followed_user)
    end

    test "it doesn't create a notification for follow-unfollow-follow chains" do
--- a/test/upload_test.exs
+++ b/test/upload_test.exs
@ -54,6 +54,7 @@ test "it returns file" do
                %{
                  "name" => "image.jpg",
                  "type" => "Document",
+                  "mediaType" => "image/jpeg",
                  "url" => [
                    %{
                      "href" => "http://localhost:4001/media/post-process-file.jpg",
--- a/test/web/activity_pub/object_validator_test.exs
+++ b/test/web/activity_pub/object_validator_test.exs
@ -2,14 +2,264 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidatorTest do
  use Pleroma.DataCase

  alias Pleroma.Object
+  alias Pleroma.Web.ActivityPub.ActivityPub
  alias Pleroma.Web.ActivityPub.Builder
  alias Pleroma.Web.ActivityPub.ObjectValidator
+  alias Pleroma.Web.ActivityPub.ObjectValidators.AttachmentValidator
  alias Pleroma.Web.ActivityPub.ObjectValidators.LikeValidator
  alias Pleroma.Web.ActivityPub.Utils
  alias Pleroma.Web.CommonAPI

  import Pleroma.Factory

+  describe "attachments" do
+    test "works with honkerific attachments" do
+      attachment = %{
+        "mediaType" => "",
+        "name" => "",
+        "summary" => "298p3RG7j27tfsZ9RQ.jpg",
+        "type" => "Document",
+        "url" => "https://honk.tedunangst.com/d/298p3RG7j27tfsZ9RQ.jpg"
+      }
+
+      assert {:ok, attachment} =
+               AttachmentValidator.cast_and_validate(attachment)
+               |> Ecto.Changeset.apply_action(:insert)
+
+      assert attachment.mediaType == "application/octet-stream"
+    end
+
+    test "it turns mastodon attachments into our attachments" do
+      attachment = %{
+        "url" =>
+          "http://mastodon.example.org/system/media_attachments/files/000/000/002/original/334ce029e7bfb920.jpg",
+        "type" => "Document",
+        "name" => nil,
+        "mediaType" => "image/jpeg"
+      }
+
+      {:ok, attachment} =
+        AttachmentValidator.cast_and_validate(attachment)
+        |> Ecto.Changeset.apply_action(:insert)
+
+      assert [
+               %{
+                 href:
+                   "http://mastodon.example.org/system/media_attachments/files/000/000/002/original/334ce029e7bfb920.jpg",
+                 type: "Link",
+                 mediaType: "image/jpeg"
+               }
+             ] = attachment.url
+
+      assert attachment.mediaType == "image/jpeg"
+    end
+
+    test "it handles our own uploads" do
+      user = insert(:user)
+
+      file = %Plug.Upload{
+        content_type: "image/jpg",
+        path: Path.absname("test/fixtures/image.jpg"),
+        filename: "an_image.jpg"
+      }
+
+      {:ok, attachment} = ActivityPub.upload(file, actor: user.ap_id)
+
+      {:ok, attachment} =
+        attachment.data
+        |> AttachmentValidator.cast_and_validate()
+        |> Ecto.Changeset.apply_action(:insert)
+
+      assert attachment.mediaType == "image/jpeg"
+    end
+  end
+
+  describe "chat message create activities" do
+    test "it is invalid if the object already exists" do
+      user = insert(:user)
+      recipient = insert(:user)
+      {:ok, activity} = CommonAPI.post_chat_message(user, recipient, "hey")
+      object = Object.normalize(activity, false)
+
+      {:ok, create_data, _} = Builder.create(user, object.data, [recipient.ap_id])
+
+      {:error, cng} = ObjectValidator.validate(create_data, [])
+
+      assert {:object, {"The object to create already exists", []}} in cng.errors
+    end
+
+    test "it is invalid if the object data has a different `to` or `actor` field" do
+      user = insert(:user)
+      recipient = insert(:user)
+      {:ok, object_data, _} = Builder.chat_message(recipient, user.ap_id, "Hey")
+
+      {:ok, create_data, _} = Builder.create(user, object_data, [recipient.ap_id])
+
+      {:error, cng} = ObjectValidator.validate(create_data, [])
+
+      assert {:to, {"Recipients don't match with object recipients", []}} in cng.errors
+      assert {:actor, {"Actor doesn't match with object actor", []}} in cng.errors
+    end
+  end
+
+  describe "chat messages" do
+    setup do
+      clear_config([:instance, :remote_limit])
+      user = insert(:user)
+      recipient = insert(:user, local: false)
+
+      {:ok, valid_chat_message, _} = Builder.chat_message(user, recipient.ap_id, "hey :firefox:")
+
+      %{user: user, recipient: recipient, valid_chat_message: valid_chat_message}
+    end
+
+    test "let's through some basic html", %{user: user, recipient: recipient} do
+      {:ok, valid_chat_message, _} =
+        Builder.chat_message(
+          user,
+          recipient.ap_id,
+          "hey <a href='https://example.org'>example</a> <script>alert('uguu')</script>"
+        )
+
+      assert {:ok, object, _meta} = ObjectValidator.validate(valid_chat_message, [])
+
+      assert object["content"] ==
+               "hey <a href=\"https://example.org\">example</a> alert(&#39;uguu&#39;)"
+    end
+
+    test "validates for a basic object we build", %{valid_chat_message: valid_chat_message} do
+      assert {:ok, object, _meta} = ObjectValidator.validate(valid_chat_message, [])
+
+      assert Map.put(valid_chat_message, "attachment", nil) == object
+    end
+
+    test "validates for a basic object with an attachment", %{
+      valid_chat_message: valid_chat_message,
+      user: user
+    } do
+      file = %Plug.Upload{
+        content_type: "image/jpg",
+        path: Path.absname("test/fixtures/image.jpg"),
+        filename: "an_image.jpg"
+      }
+
+      {:ok, attachment} = ActivityPub.upload(file, actor: user.ap_id)
+
+      valid_chat_message =
+        valid_chat_message
+        |> Map.put("attachment", attachment.data)
+
+      assert {:ok, object, _meta} = ObjectValidator.validate(valid_chat_message, [])
+
+      assert object["attachment"]
+    end
+
+    test "validates for a basic object with an attachment in an array", %{
+      valid_chat_message: valid_chat_message,
+      user: user
+    } do
+      file = %Plug.Upload{
+        content_type: "image/jpg",
+        path: Path.absname("test/fixtures/image.jpg"),
+        filename: "an_image.jpg"
+      }
+
+      {:ok, attachment} = ActivityPub.upload(file, actor: user.ap_id)
+
+      valid_chat_message =
+        valid_chat_message
+        |> Map.put("attachment", [attachment.data])
+
+      assert {:ok, object, _meta} = ObjectValidator.validate(valid_chat_message, [])
+
+      assert object["attachment"]
+    end
+
+    test "validates for a basic object with an attachment but without content", %{
+      valid_chat_message: valid_chat_message,
+      user: user
+    } do
+      file = %Plug.Upload{
+        content_type: "image/jpg",
+        path: Path.absname("test/fixtures/image.jpg"),
+        filename: "an_image.jpg"
+      }
+
+      {:ok, attachment} = ActivityPub.upload(file, actor: user.ap_id)
+
+      valid_chat_message =
+        valid_chat_message
+        |> Map.put("attachment", attachment.data)
+        |> Map.delete("content")
+
+      assert {:ok, object, _meta} = ObjectValidator.validate(valid_chat_message, [])
+
+      assert object["attachment"]
+    end
+
+    test "does not validate if the message has no content", %{
+      valid_chat_message: valid_chat_message
+    } do
+      contentless =
+        valid_chat_message
+        |> Map.delete("content")
+
+      refute match?({:ok, _object, _meta}, ObjectValidator.validate(contentless, []))
+    end
+
+    test "does not validate if the message is longer than the remote_limit", %{
+      valid_chat_message: valid_chat_message
+    } do
+      Pleroma.Config.put([:instance, :remote_limit], 2)
+      refute match?({:ok, _object, _meta}, ObjectValidator.validate(valid_chat_message, []))
+    end
+
+    test "does not validate if the recipient is blocking the actor", %{
+      valid_chat_message: valid_chat_message,
+      user: user,
+      recipient: recipient
+    } do
+      Pleroma.User.block(recipient, user)
+      refute match?({:ok, _object, _meta}, ObjectValidator.validate(valid_chat_message, []))
+    end
+
+    test "does not validate if the actor or the recipient is not in our system", %{
+      valid_chat_message: valid_chat_message
+    } do
+      chat_message =
+        valid_chat_message
+        |> Map.put("actor", "https://raymoo.com/raymoo")
+
+      {:error, _} = ObjectValidator.validate(chat_message, [])
+
+      chat_message =
+        valid_chat_message
+        |> Map.put("to", ["https://raymoo.com/raymoo"])
+
+      {:error, _} = ObjectValidator.validate(chat_message, [])
+    end
+
+    test "does not validate for a message with multiple recipients", %{
+      valid_chat_message: valid_chat_message,
+      user: user,
+      recipient: recipient
+    } do
+      chat_message =
+        valid_chat_message
+        |> Map.put("to", [user.ap_id, recipient.ap_id])
+
+      assert {:error, _} = ObjectValidator.validate(chat_message, [])
+    end
+
+    test "does not validate if it doesn't concern local users" do
+      user = insert(:user, local: false)
+      recipient = insert(:user, local: false)
+
+      {:ok, valid_chat_message, _} = Builder.chat_message(user, recipient.ap_id, "hey")
+      assert {:error, _} = ObjectValidator.validate(valid_chat_message, [])
+    end
+  end
+
  describe "EmojiReacts" do
    setup do
      user = insert(:user)
--- a/test/web/activity_pub/object_validators/types/object_id_test.exs
+++ b/test/web/activity_pub/object_validators/types/object_id_test.exs
@ -1,3 +1,7 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
 defmodule Pleroma.Web.ObjectValidators.Types.ObjectIDTest do
  alias Pleroma.Web.ActivityPub.ObjectValidators.Types.ObjectID
  use Pleroma.DataCase
--- a/test/web/activity_pub/object_validators/types/safe_text_test.exs
+++ b/test/web/activity_pub/object_validators/types/safe_text_test.exs
@ -0,0 +1,30 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.Types.SafeTextTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types.SafeText
+
+  test "it lets normal text go through" do
+    text = "hey how are you"
+    assert {:ok, text} == SafeText.cast(text)
+  end
+
+  test "it removes html tags from text" do
+    text = "hey look xss <script>alert('foo')</script>"
+    assert {:ok, "hey look xss alert(&#39;foo&#39;)"} == SafeText.cast(text)
+  end
+
+  test "it keeps basic html tags" do
+    text = "hey <a href='http://gensokyo.2hu'>look</a> xss <script>alert('foo')</script>"
+
+    assert {:ok, "hey <a href=\"http://gensokyo.2hu\">look</a> xss alert(&#39;foo&#39;)"} ==
+             SafeText.cast(text)
+  end
+
+  test "errors for non-text" do
+    assert :error == SafeText.cast(1)
+  end
+end
--- a/test/web/activity_pub/pipeline_test.exs
+++ b/test/web/activity_pub/pipeline_test.exs
@ -33,7 +33,10 @@ test "it goes through validation, filtering, persisting, side effects and federa
        {
          Pleroma.Web.ActivityPub.SideEffects,
          [],
-          [handle: fn o, m -> {:ok, o, m} end]
+          [
+            handle: fn o, m -> {:ok, o, m} end,
+            handle_after_transaction: fn m -> m end
+          ]
        },
        {
          Pleroma.Web.Federator,
@ -71,7 +74,7 @@ test "it goes through validation, filtering, persisting, side effects without fe
        {
          Pleroma.Web.ActivityPub.SideEffects,
          [],
-          [handle: fn o, m -> {:ok, o, m} end]
+          [handle: fn o, m -> {:ok, o, m} end, handle_after_transaction: fn m -> m end]
        },
        {
          Pleroma.Web.Federator,
@ -110,7 +113,7 @@ test "it goes through validation, filtering, persisting, side effects without fe
        {
          Pleroma.Web.ActivityPub.SideEffects,
          [],
-          [handle: fn o, m -> {:ok, o, m} end]
+          [handle: fn o, m -> {:ok, o, m} end, handle_after_transaction: fn m -> m end]
        },
        {
          Pleroma.Web.Federator,
--- a/test/web/activity_pub/side_effects_test.exs
+++ b/test/web/activity_pub/side_effects_test.exs
@ -7,6 +7,8 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
  use Pleroma.DataCase

  alias Pleroma.Activity
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
  alias Pleroma.Notification
  alias Pleroma.Object
  alias Pleroma.Repo
@ -20,6 +22,48 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
  import Pleroma.Factory
  import Mock

+  describe "handle_after_transaction" do
+    test "it streams out notifications and streams" do
+      author = insert(:user, local: true)
+      recipient = insert(:user, local: true)
+
+      {:ok, chat_message_data, _meta} = Builder.chat_message(author, recipient.ap_id, "hey")
+
+      {:ok, create_activity_data, _meta} =
+        Builder.create(author, chat_message_data["id"], [recipient.ap_id])
+
+      {:ok, create_activity, _meta} = ActivityPub.persist(create_activity_data, local: false)
+
+      {:ok, _create_activity, meta} =
+        SideEffects.handle(create_activity, local: false, object_data: chat_message_data)
+
+      assert [notification] = meta[:notifications]
+
+      with_mocks([
+        {
+          Pleroma.Web.Streamer,
+          [],
+          [
+            stream: fn _, _ -> nil end
+          ]
+        },
+        {
+          Pleroma.Web.Push,
+          [],
+          [
+            send: fn _ -> nil end
+          ]
+        }
+      ]) do
+        SideEffects.handle_after_transaction(meta)
+
+        assert called(Pleroma.Web.Streamer.stream(["user", "user:notification"], notification))
+        assert called(Pleroma.Web.Streamer.stream(["user", "user:pleroma_chat"], :_))
+        assert called(Pleroma.Web.Push.send(notification))
+      end
+    end
+  end
+
  describe "delete objects" do
    setup do
      user = insert(:user)
@ -290,6 +334,147 @@ test "creates a notification", %{like: like, poster: poster} do
    end
  end

+  describe "creation of ChatMessages" do
+    test "notifies the recipient" do
+      author = insert(:user, local: false)
+      recipient = insert(:user, local: true)
+
+      {:ok, chat_message_data, _meta} = Builder.chat_message(author, recipient.ap_id, "hey")
+
+      {:ok, create_activity_data, _meta} =
+        Builder.create(author, chat_message_data["id"], [recipient.ap_id])
+
+      {:ok, create_activity, _meta} = ActivityPub.persist(create_activity_data, local: false)
+
+      {:ok, _create_activity, _meta} =
+        SideEffects.handle(create_activity, local: false, object_data: chat_message_data)
+
+      assert Repo.get_by(Notification, user_id: recipient.id, activity_id: create_activity.id)
+    end
+
+    test "it streams the created ChatMessage" do
+      author = insert(:user, local: true)
+      recipient = insert(:user, local: true)
+
+      {:ok, chat_message_data, _meta} = Builder.chat_message(author, recipient.ap_id, "hey")
+
+      {:ok, create_activity_data, _meta} =
+        Builder.create(author, chat_message_data["id"], [recipient.ap_id])
+
+      {:ok, create_activity, _meta} = ActivityPub.persist(create_activity_data, local: false)
+
+      {:ok, _create_activity, meta} =
+        SideEffects.handle(create_activity, local: false, object_data: chat_message_data)
+
+      assert [_, _] = meta[:streamables]
+    end
+
+    test "it creates a Chat and MessageReferences for the local users and bumps the unread count, except for the author" do
+      author = insert(:user, local: true)
+      recipient = insert(:user, local: true)
+
+      {:ok, chat_message_data, _meta} = Builder.chat_message(author, recipient.ap_id, "hey")
+
+      {:ok, create_activity_data, _meta} =
+        Builder.create(author, chat_message_data["id"], [recipient.ap_id])
+
+      {:ok, create_activity, _meta} = ActivityPub.persist(create_activity_data, local: false)
+
+      with_mocks([
+        {
+          Pleroma.Web.Streamer,
+          [],
+          [
+            stream: fn _, _ -> nil end
+          ]
+        },
+        {
+          Pleroma.Web.Push,
+          [],
+          [
+            send: fn _ -> nil end
+          ]
+        }
+      ]) do
+        {:ok, _create_activity, meta} =
+          SideEffects.handle(create_activity, local: false, object_data: chat_message_data)
+
+        # The notification gets created
+        assert [notification] = meta[:notifications]
+        assert notification.activity_id == create_activity.id
+
+        # But it is not sent out
+        refute called(Pleroma.Web.Streamer.stream(["user", "user:notification"], notification))
+        refute called(Pleroma.Web.Push.send(notification))
+
+        # Same for the user chat stream
+        assert [{topics, _}, _] = meta[:streamables]
+        assert topics == ["user", "user:pleroma_chat"]
+        refute called(Pleroma.Web.Streamer.stream(["user", "user:pleroma_chat"], :_))
+
+        chat = Chat.get(author.id, recipient.ap_id)
+
+        [cm_ref] = MessageReference.for_chat_query(chat) |> Repo.all()
+
+        assert cm_ref.object.data["content"] == "hey"
+        assert cm_ref.unread == false
+
+        chat = Chat.get(recipient.id, author.ap_id)
+
+        [cm_ref] = MessageReference.for_chat_query(chat) |> Repo.all()
+
+        assert cm_ref.object.data["content"] == "hey"
+        assert cm_ref.unread == true
+      end
+    end
+
+    test "it creates a Chat for the local users and bumps the unread count" do
+      author = insert(:user, local: false)
+      recipient = insert(:user, local: true)
+
+      {:ok, chat_message_data, _meta} = Builder.chat_message(author, recipient.ap_id, "hey")
+
+      {:ok, create_activity_data, _meta} =
+        Builder.create(author, chat_message_data["id"], [recipient.ap_id])
+
+      {:ok, create_activity, _meta} = ActivityPub.persist(create_activity_data, local: false)
+
+      {:ok, _create_activity, _meta} =
+        SideEffects.handle(create_activity, local: false, object_data: chat_message_data)
+
+      # An object is created
+      assert Object.get_by_ap_id(chat_message_data["id"])
+
+      # The remote user won't get a chat
+      chat = Chat.get(author.id, recipient.ap_id)
+      refute chat
+
+      # The local user will get a chat
+      chat = Chat.get(recipient.id, author.ap_id)
+      assert chat
+
+      author = insert(:user, local: true)
+      recipient = insert(:user, local: true)
+
+      {:ok, chat_message_data, _meta} = Builder.chat_message(author, recipient.ap_id, "hey")
+
+      {:ok, create_activity_data, _meta} =
+        Builder.create(author, chat_message_data["id"], [recipient.ap_id])
+
+      {:ok, create_activity, _meta} = ActivityPub.persist(create_activity_data, local: false)
+
+      {:ok, _create_activity, _meta} =
+        SideEffects.handle(create_activity, local: false, object_data: chat_message_data)
+
+      # Both users are local and get the chat
+      chat = Chat.get(author.id, recipient.ap_id)
+      assert chat
+
+      chat = Chat.get(recipient.id, author.ap_id)
+      assert chat
+    end
+  end
+
  describe "announce objects" do
    setup do
      poster = insert(:user)
--- a/test/web/activity_pub/transmogrifier/chat_message_test.exs
+++ b/test/web/activity_pub/transmogrifier/chat_message_test.exs
@ -0,0 +1,153 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.Transmogrifier.ChatMessageTest do
+  use Pleroma.DataCase
+
+  import Pleroma.Factory
+
+  alias Pleroma.Activity
+  alias Pleroma.Chat
+  alias Pleroma.Object
+  alias Pleroma.Web.ActivityPub.Transmogrifier
+
+  describe "handle_incoming" do
+    test "handles chonks with attachment" do
+      data = %{
+        "@context" => "https://www.w3.org/ns/activitystreams",
+        "actor" => "https://honk.tedunangst.com/u/tedu",
+        "id" => "https://honk.tedunangst.com/u/tedu/honk/x6gt8X8PcyGkQcXxzg1T",
+        "object" => %{
+          "attachment" => [
+            %{
+              "mediaType" => "image/jpeg",
+              "name" => "298p3RG7j27tfsZ9RQ.jpg",
+              "summary" => "298p3RG7j27tfsZ9RQ.jpg",
+              "type" => "Document",
+              "url" => "https://honk.tedunangst.com/d/298p3RG7j27tfsZ9RQ.jpg"
+            }
+          ],
+          "attributedTo" => "https://honk.tedunangst.com/u/tedu",
+          "content" => "",
+          "id" => "https://honk.tedunangst.com/u/tedu/chonk/26L4wl5yCbn4dr4y1b",
+          "published" => "2020-05-18T01:13:03Z",
+          "to" => [
+            "https://dontbulling.me/users/lain"
+          ],
+          "type" => "ChatMessage"
+        },
+        "published" => "2020-05-18T01:13:03Z",
+        "to" => [
+          "https://dontbulling.me/users/lain"
+        ],
+        "type" => "Create"
+      }
+
+      _user = insert(:user, ap_id: data["actor"])
+      _user = insert(:user, ap_id: hd(data["to"]))
+
+      assert {:ok, _activity} = Transmogrifier.handle_incoming(data)
+    end
+
+    test "it rejects messages that don't contain content" do
+      data =
+        File.read!("test/fixtures/create-chat-message.json")
+        |> Poison.decode!()
+
+      object =
+        data["object"]
+        |> Map.delete("content")
+
+      data =
+        data
+        |> Map.put("object", object)
+
+      _author =
+        insert(:user, ap_id: data["actor"], local: false, last_refreshed_at: DateTime.utc_now())
+
+      _recipient =
+        insert(:user,
+          ap_id: List.first(data["to"]),
+          local: true,
+          last_refreshed_at: DateTime.utc_now()
+        )
+
+      {:error, _} = Transmogrifier.handle_incoming(data)
+    end
+
+    test "it rejects messages that don't concern local users" do
+      data =
+        File.read!("test/fixtures/create-chat-message.json")
+        |> Poison.decode!()
+
+      _author =
+        insert(:user, ap_id: data["actor"], local: false, last_refreshed_at: DateTime.utc_now())
+
+      _recipient =
+        insert(:user,
+          ap_id: List.first(data["to"]),
+          local: false,
+          last_refreshed_at: DateTime.utc_now()
+        )
+
+      {:error, _} = Transmogrifier.handle_incoming(data)
+    end
+
+    test "it rejects messages where the `to` field of activity and object don't match" do
+      data =
+        File.read!("test/fixtures/create-chat-message.json")
+        |> Poison.decode!()
+
+      author = insert(:user, ap_id: data["actor"])
+      _recipient = insert(:user, ap_id: List.first(data["to"]))
+
+      data =
+        data
+        |> Map.put("to", author.ap_id)
+
+      assert match?({:error, _}, Transmogrifier.handle_incoming(data))
+      refute Object.get_by_ap_id(data["object"]["id"])
+    end
+
+    test "it fetches the actor if they aren't in our system" do
+      Tesla.Mock.mock(fn env -> apply(HttpRequestMock, :request, [env]) end)
+
+      data =
+        File.read!("test/fixtures/create-chat-message.json")
+        |> Poison.decode!()
+        |> Map.put("actor", "http://mastodon.example.org/users/admin")
+        |> put_in(["object", "actor"], "http://mastodon.example.org/users/admin")
+
+      _recipient = insert(:user, ap_id: List.first(data["to"]), local: true)
+
+      {:ok, %Activity{} = _activity} = Transmogrifier.handle_incoming(data)
+    end
+
+    test "it inserts it and creates a chat" do
+      data =
+        File.read!("test/fixtures/create-chat-message.json")
+        |> Poison.decode!()
+
+      author =
+        insert(:user, ap_id: data["actor"], local: false, last_refreshed_at: DateTime.utc_now())
+
+      recipient = insert(:user, ap_id: List.first(data["to"]), local: true)
+
+      {:ok, %Activity{} = activity} = Transmogrifier.handle_incoming(data)
+      assert activity.local == false
+
+      assert activity.actor == author.ap_id
+      assert activity.recipients == [recipient.ap_id, author.ap_id]
+
+      %Object{} = object = Object.get_by_ap_id(activity.data["object"])
+
+      assert object
+      assert object.data["content"] == "You expected a cute girl? Too bad. alert(&#39;XSS&#39;)"
+      assert match?(%{"firefox" => _}, object.data["emoji"])
+
+      refute Chat.get(author.id, recipient.ap_id)
+      assert Chat.get(recipient.id, author.ap_id)
+    end
+  end
+end
--- a/test/web/activity_pub/transmogrifier/follow_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/follow_handling_test.exs
@ -5,6 +5,7 @@
 defmodule Pleroma.Web.ActivityPub.Transmogrifier.FollowHandlingTest do
  use Pleroma.DataCase
  alias Pleroma.Activity
+  alias Pleroma.Notification
  alias Pleroma.Repo
  alias Pleroma.User
  alias Pleroma.Web.ActivityPub.Transmogrifier
@ -12,6 +13,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier.FollowHandlingTest do

  import Pleroma.Factory
  import Ecto.Query
+  import Mock

  setup_all do
    Tesla.Mock.mock_global(fn env -> apply(HttpRequestMock, :request, [env]) end)
@ -57,9 +59,12 @@ test "it works for incoming follow requests" do
      activity = Repo.get(Activity, activity.id)
      assert activity.data["state"] == "accept"
      assert User.following?(User.get_cached_by_ap_id(data["actor"]), user)
+
+      [notification] = Notification.for_user(user)
+      assert notification.type == "follow"
    end

-    test "with locked accounts, it does not create a follow or an accept" do
+    test "with locked accounts, it does create a Follow, but not an Accept" do
      user = insert(:user, locked: true)

      data =
@ -81,6 +86,9 @@ test "with locked accounts, it does not create a follow or an accept" do
        |> Repo.all()

      assert Enum.empty?(accepts)
+
+      [notification] = Notification.for_user(user)
+      assert notification.type == "follow_request"
    end

    test "it works for follow requests when you are already followed, creating a new accept activity" do
@ -144,6 +152,23 @@ test "it rejects incoming follow requests from blocked users when deny_follow_bl
      assert activity.data["state"] == "reject"
    end

+    test "it rejects incoming follow requests if the following errors for some reason" do
+      user = insert(:user)
+
+      data =
+        File.read!("test/fixtures/mastodon-follow-activity.json")
+        |> Poison.decode!()
+        |> Map.put("object", user.ap_id)
+
+      with_mock Pleroma.User, [:passthrough], follow: fn _, _ -> {:error, :testing} end do
+        {:ok, %Activity{data: %{"id" => id}}} = Transmogrifier.handle_incoming(data)
+
+        %Activity{} = activity = Activity.get_by_ap_id(id)
+
+        assert activity.data["state"] == "reject"
+      end
+    end
+
    test "it works for incoming follow requests from hubzilla" do
      user = insert(:user)

--- a/test/web/common_api/common_api_test.exs
+++ b/test/web/common_api/common_api_test.exs
@ -5,7 +5,9 @@
 defmodule Pleroma.Web.CommonAPITest do
  use Pleroma.DataCase
  alias Pleroma.Activity
+  alias Pleroma.Chat
  alias Pleroma.Conversation.Participation
+  alias Pleroma.Notification
  alias Pleroma.Object
  alias Pleroma.User
  alias Pleroma.Web.ActivityPub.ActivityPub
@ -23,6 +25,150 @@ defmodule Pleroma.Web.CommonAPITest do
  setup do: clear_config([:instance, :limit])
  setup do: clear_config([:instance, :max_pinned_statuses])

+  describe "posting chat messages" do
+    setup do: clear_config([:instance, :chat_limit])
+
+    test "it posts a chat message without content but with an attachment" do
+      author = insert(:user)
+      recipient = insert(:user)
+
+      file = %Plug.Upload{
+        content_type: "image/jpg",
+        path: Path.absname("test/fixtures/image.jpg"),
+        filename: "an_image.jpg"
+      }
+
+      {:ok, upload} = ActivityPub.upload(file, actor: author.ap_id)
+
+      with_mocks([
+        {
+          Pleroma.Web.Streamer,
+          [],
+          [
+            stream: fn _, _ ->
+              nil
+            end
+          ]
+        },
+        {
+          Pleroma.Web.Push,
+          [],
+          [
+            send: fn _ -> nil end
+          ]
+        }
+      ]) do
+        {:ok, activity} =
+          CommonAPI.post_chat_message(
+            author,
+            recipient,
+            nil,
+            media_id: upload.id
+          )
+
+        notification =
+          Notification.for_user_and_activity(recipient, activity)
+          |> Repo.preload(:activity)
+
+        assert called(Pleroma.Web.Push.send(notification))
+        assert called(Pleroma.Web.Streamer.stream(["user", "user:notification"], notification))
+        assert called(Pleroma.Web.Streamer.stream(["user", "user:pleroma_chat"], :_))
+
+        assert activity
+      end
+    end
+
+    test "it adds html newlines" do
+      author = insert(:user)
+      recipient = insert(:user)
+
+      other_user = insert(:user)
+
+      {:ok, activity} =
+        CommonAPI.post_chat_message(
+          author,
+          recipient,
+          "uguu\nuguuu"
+        )
+
+      assert other_user.ap_id not in activity.recipients
+
+      object = Object.normalize(activity, false)
+
+      assert object.data["content"] == "uguu<br/>uguuu"
+    end
+
+    test "it linkifies" do
+      author = insert(:user)
+      recipient = insert(:user)
+
+      other_user = insert(:user)
+
+      {:ok, activity} =
+        CommonAPI.post_chat_message(
+          author,
+          recipient,
+          "https://example.org is the site of @#{other_user.nickname} #2hu"
+        )
+
+      assert other_user.ap_id not in activity.recipients
+
+      object = Object.normalize(activity, false)
+
+      assert object.data["content"] ==
+               "<a href=\"https://example.org\" rel=\"ugc\">https://example.org</a> is the site of <span class=\"h-card\"><a class=\"u-url mention\" data-user=\"#{
+                 other_user.id
+               }\" href=\"#{other_user.ap_id}\" rel=\"ugc\">@<span>#{other_user.nickname}</span></a></span> <a class=\"hashtag\" data-tag=\"2hu\" href=\"http://localhost:4001/tag/2hu\">#2hu</a>"
+    end
+
+    test "it posts a chat message" do
+      author = insert(:user)
+      recipient = insert(:user)
+
+      {:ok, activity} =
+        CommonAPI.post_chat_message(
+          author,
+          recipient,
+          "a test message <script>alert('uuu')</script> :firefox:"
+        )
+
+      assert activity.data["type"] == "Create"
+      assert activity.local
+      object = Object.normalize(activity)
+
+      assert object.data["type"] == "ChatMessage"
+      assert object.data["to"] == [recipient.ap_id]
+
+      assert object.data["content"] ==
+               "a test message &lt;script&gt;alert(&#39;uuu&#39;)&lt;/script&gt; :firefox:"
+
+      assert object.data["emoji"] == %{
+               "firefox" => "http://localhost:4001/emoji/Firefox.gif"
+             }
+
+      assert Chat.get(author.id, recipient.ap_id)
+      assert Chat.get(recipient.id, author.ap_id)
+
+      assert :ok == Pleroma.Web.Federator.perform(:publish, activity)
+    end
+
+    test "it reject messages over the local limit" do
+      Pleroma.Config.put([:instance, :chat_limit], 2)
+
+      author = insert(:user)
+      recipient = insert(:user)
+
+      {:error, message} =
+        CommonAPI.post_chat_message(
+          author,
+          recipient,
+          "123"
+        )
+
+      assert message == :content_too_long
+    end
+  end
+
  describe "unblocking" do
    test "it works even without an existing block activity" do
      blocked = insert(:user)
--- a/test/web/mastodon_api/controllers/notification_controller_test.exs
+++ b/test/web/mastodon_api/controllers/notification_controller_test.exs
@ -54,6 +54,27 @@ test "list of notifications" do
    assert response == expected_response
  end

+  test "by default, does not contain pleroma:chat_mention" do
+    %{user: user, conn: conn} = oauth_access(["read:notifications"])
+    other_user = insert(:user)
+
+    {:ok, _activity} = CommonAPI.post_chat_message(other_user, user, "hey")
+
+    result =
+      conn
+      |> get("/api/v1/notifications")
+      |> json_response_and_validate_schema(200)
+
+    assert [] == result
+
+    result =
+      conn
+      |> get("/api/v1/notifications?include_types[]=pleroma:chat_mention")
+      |> json_response_and_validate_schema(200)
+
+    assert [_] = result
+  end
+
  test "getting a single notification" do
    %{user: user, conn: conn} = oauth_access(["read:notifications"])
    other_user = insert(:user)
--- a/test/web/mastodon_api/controllers/search_controller_test.exs
+++ b/test/web/mastodon_api/controllers/search_controller_test.exs
@ -111,6 +111,15 @@ test "constructs hashtags from search query", %{conn: conn} do
               %{"name" => "prone", "url" => "#{Web.base_url()}/tag/prone"},
               %{"name" => "AccidentProne", "url" => "#{Web.base_url()}/tag/AccidentProne"}
             ]
+
+      results =
+        conn
+        |> get("/api/v2/search?#{URI.encode_query(%{q: "https://shpposter.club/users/shpuld"})}")
+        |> json_response_and_validate_schema(200)
+
+      assert results["hashtags"] == [
+               %{"name" => "shpuld", "url" => "#{Web.base_url()}/tag/shpuld"}
+             ]
    end

    test "excludes a blocked users from search results", %{conn: conn} do
--- a/test/web/mastodon_api/controllers/subscription_controller_test.exs
+++ b/test/web/mastodon_api/controllers/subscription_controller_test.exs
@ -58,7 +58,9 @@ test "successful creation", %{conn: conn} do
      result =
        conn
        |> post("/api/v1/push/subscription", %{
-          "data" => %{"alerts" => %{"mention" => true, "test" => true}},
+          "data" => %{
+            "alerts" => %{"mention" => true, "test" => true, "pleroma:chat_mention" => true}
+          },
          "subscription" => @sub
        })
        |> json_response_and_validate_schema(200)
@ -66,7 +68,7 @@ test "successful creation", %{conn: conn} do
      [subscription] = Pleroma.Repo.all(Subscription)

      assert %{
-               "alerts" => %{"mention" => true},
+               "alerts" => %{"mention" => true, "pleroma:chat_mention" => true},
               "endpoint" => subscription.endpoint,
               "id" => to_string(subscription.id),
               "server_key" => @server_key
--- a/test/web/mastodon_api/views/account_view_test.exs
+++ b/test/web/mastodon_api/views/account_view_test.exs
@ -72,6 +72,7 @@ test "Represent a user account" do
        fields: []
      },
      pleroma: %{
+        ap_id: user.ap_id,
        background_image: "https://example.com/images/asuka_hospital.png",
        confirmation_pending: false,
        tags: [],
@ -148,6 +149,7 @@ test "Represent a Service(bot) account" do
        fields: []
      },
      pleroma: %{
+        ap_id: user.ap_id,
        background_image: nil,
        confirmation_pending: false,
        tags: [],
--- a/test/web/mastodon_api/views/notification_view_test.exs
+++ b/test/web/mastodon_api/views/notification_view_test.exs
@ -6,7 +6,10 @@ defmodule Pleroma.Web.MastodonAPI.NotificationViewTest do
  use Pleroma.DataCase

  alias Pleroma.Activity
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
  alias Pleroma.Notification
+  alias Pleroma.Object
  alias Pleroma.Repo
  alias Pleroma.User
  alias Pleroma.Web.CommonAPI
@ -14,6 +17,7 @@ defmodule Pleroma.Web.MastodonAPI.NotificationViewTest do
  alias Pleroma.Web.MastodonAPI.AccountView
  alias Pleroma.Web.MastodonAPI.NotificationView
  alias Pleroma.Web.MastodonAPI.StatusView
+  alias Pleroma.Web.PleromaAPI.Chat.MessageReferenceView
  import Pleroma.Factory

  defp test_notifications_rendering(notifications, user, expected_result) do
@ -31,6 +35,30 @@ defp test_notifications_rendering(notifications, user, expected_result) do
    assert expected_result == result
  end

+  test "ChatMessage notification" do
+    user = insert(:user)
+    recipient = insert(:user)
+    {:ok, activity} = CommonAPI.post_chat_message(user, recipient, "what's up my dude")
+
+    {:ok, [notification]} = Notification.create_notifications(activity)
+
+    object = Object.normalize(activity)
+    chat = Chat.get(recipient.id, user.ap_id)
+
+    cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+    expected = %{
+      id: to_string(notification.id),
+      pleroma: %{is_seen: false},
+      type: "pleroma:chat_mention",
+      account: AccountView.render("show.json", %{user: user, for: recipient}),
+      chat_message: MessageReferenceView.render("show.json", %{chat_message_reference: cm_ref}),
+      created_at: Utils.to_masto_date(notification.inserted_at)
+    }
+
+    test_notifications_rendering([notification], recipient, [expected])
+  end
+
  test "Mention notification" do
    user = insert(:user)
    mentioned_user = insert(:user)
--- a/test/web/node_info_test.exs
+++ b/test/web/node_info_test.exs
@ -145,7 +145,8 @@ test "it shows default features flags", %{conn: conn} do
      "shareable_emoji_packs",
      "multifetch",
      "pleroma_emoji_reactions",
-      "pleroma:api/v1/notifications:include_types_filter"
+      "pleroma:api/v1/notifications:include_types_filter",
+      "pleroma_chat_messages"
    ]

    assert MapSet.subset?(
--- a/test/web/pleroma_api/controllers/chat_controller_test.exs
+++ b/test/web/pleroma_api/controllers/chat_controller_test.exs
@ -0,0 +1,336 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+defmodule Pleroma.Web.PleromaAPI.ChatControllerTest do
+  use Pleroma.Web.ConnCase, async: true
+
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
+  alias Pleroma.Object
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.Web.CommonAPI
+
+  import Pleroma.Factory
+
+  describe "POST /api/v1/pleroma/chats/:id/messages/:message_id/read" do
+    setup do: oauth_access(["write:chats"])
+
+    test "it marks one message as read", %{conn: conn, user: user} do
+      other_user = insert(:user)
+
+      {:ok, create} = CommonAPI.post_chat_message(other_user, user, "sup")
+      {:ok, _create} = CommonAPI.post_chat_message(other_user, user, "sup part 2")
+      {:ok, chat} = Chat.get_or_create(user.id, other_user.ap_id)
+      object = Object.normalize(create, false)
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+      assert cm_ref.unread == true
+
+      result =
+        conn
+        |> post("/api/v1/pleroma/chats/#{chat.id}/messages/#{cm_ref.id}/read")
+        |> json_response_and_validate_schema(200)
+
+      assert result["unread"] == false
+
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+      assert cm_ref.unread == false
+    end
+  end
+
+  describe "POST /api/v1/pleroma/chats/:id/read" do
+    setup do: oauth_access(["write:chats"])
+
+    test "given a `last_read_id`, it marks everything until then as read", %{
+      conn: conn,
+      user: user
+    } do
+      other_user = insert(:user)
+
+      {:ok, create} = CommonAPI.post_chat_message(other_user, user, "sup")
+      {:ok, _create} = CommonAPI.post_chat_message(other_user, user, "sup part 2")
+      {:ok, chat} = Chat.get_or_create(user.id, other_user.ap_id)
+      object = Object.normalize(create, false)
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+      assert cm_ref.unread == true
+
+      result =
+        conn
+        |> put_req_header("content-type", "application/json")
+        |> post("/api/v1/pleroma/chats/#{chat.id}/read", %{"last_read_id" => cm_ref.id})
+        |> json_response_and_validate_schema(200)
+
+      assert result["unread"] == 1
+
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+      assert cm_ref.unread == false
+    end
+  end
+
+  describe "POST /api/v1/pleroma/chats/:id/messages" do
+    setup do: oauth_access(["write:chats"])
+
+    test "it posts a message to the chat", %{conn: conn, user: user} do
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.get_or_create(user.id, other_user.ap_id)
+
+      result =
+        conn
+        |> put_req_header("content-type", "application/json")
+        |> post("/api/v1/pleroma/chats/#{chat.id}/messages", %{"content" => "Hallo!!"})
+        |> json_response_and_validate_schema(200)
+
+      assert result["content"] == "Hallo!!"
+      assert result["chat_id"] == chat.id |> to_string()
+    end
+
+    test "it fails if there is no content", %{conn: conn, user: user} do
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.get_or_create(user.id, other_user.ap_id)
+
+      result =
+        conn
+        |> put_req_header("content-type", "application/json")
+        |> post("/api/v1/pleroma/chats/#{chat.id}/messages")
+        |> json_response_and_validate_schema(400)
+
+      assert result
+    end
+
+    test "it works with an attachment", %{conn: conn, user: user} do
+      file = %Plug.Upload{
+        content_type: "image/jpg",
+        path: Path.absname("test/fixtures/image.jpg"),
+        filename: "an_image.jpg"
+      }
+
+      {:ok, upload} = ActivityPub.upload(file, actor: user.ap_id)
+
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.get_or_create(user.id, other_user.ap_id)
+
+      result =
+        conn
+        |> put_req_header("content-type", "application/json")
+        |> post("/api/v1/pleroma/chats/#{chat.id}/messages", %{
+          "media_id" => to_string(upload.id)
+        })
+        |> json_response_and_validate_schema(200)
+
+      assert result["attachment"]
+    end
+  end
+
+  describe "DELETE /api/v1/pleroma/chats/:id/messages/:message_id" do
+    setup do: oauth_access(["write:chats"])
+
+    test "it deletes a message from the chat", %{conn: conn, user: user} do
+      recipient = insert(:user)
+
+      {:ok, message} =
+        CommonAPI.post_chat_message(user, recipient, "Hello darkness my old friend")
+
+      {:ok, other_message} = CommonAPI.post_chat_message(recipient, user, "nico nico ni")
+
+      object = Object.normalize(message, false)
+
+      chat = Chat.get(user.id, recipient.ap_id)
+
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+      # Deleting your own message removes the message and the reference
+      result =
+        conn
+        |> put_req_header("content-type", "application/json")
+        |> delete("/api/v1/pleroma/chats/#{chat.id}/messages/#{cm_ref.id}")
+        |> json_response_and_validate_schema(200)
+
+      assert result["id"] == cm_ref.id
+      refute MessageReference.get_by_id(cm_ref.id)
+      assert %{data: %{"type" => "Tombstone"}} = Object.get_by_id(object.id)
+
+      # Deleting other people's messages just removes the reference
+      object = Object.normalize(other_message, false)
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+      result =
+        conn
+        |> put_req_header("content-type", "application/json")
+        |> delete("/api/v1/pleroma/chats/#{chat.id}/messages/#{cm_ref.id}")
+        |> json_response_and_validate_schema(200)
+
+      assert result["id"] == cm_ref.id
+      refute MessageReference.get_by_id(cm_ref.id)
+      assert Object.get_by_id(object.id)
+    end
+  end
+
+  describe "GET /api/v1/pleroma/chats/:id/messages" do
+    setup do: oauth_access(["read:chats"])
+
+    test "it paginates", %{conn: conn, user: user} do
+      recipient = insert(:user)
+
+      Enum.each(1..30, fn _ ->
+        {:ok, _} = CommonAPI.post_chat_message(user, recipient, "hey")
+      end)
+
+      chat = Chat.get(user.id, recipient.ap_id)
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats/#{chat.id}/messages")
+        |> json_response_and_validate_schema(200)
+
+      assert length(result) == 20
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats/#{chat.id}/messages?max_id=#{List.last(result)["id"]}")
+        |> json_response_and_validate_schema(200)
+
+      assert length(result) == 10
+    end
+
+    test "it returns the messages for a given chat", %{conn: conn, user: user} do
+      other_user = insert(:user)
+      third_user = insert(:user)
+
+      {:ok, _} = CommonAPI.post_chat_message(user, other_user, "hey")
+      {:ok, _} = CommonAPI.post_chat_message(user, third_user, "hey")
+      {:ok, _} = CommonAPI.post_chat_message(user, other_user, "how are you?")
+      {:ok, _} = CommonAPI.post_chat_message(other_user, user, "fine, how about you?")
+
+      chat = Chat.get(user.id, other_user.ap_id)
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats/#{chat.id}/messages")
+        |> json_response_and_validate_schema(200)
+
+      result
+      |> Enum.each(fn message ->
+        assert message["chat_id"] == chat.id |> to_string()
+      end)
+
+      assert length(result) == 3
+
+      # Trying to get the chat of a different user
+      result =
+        conn
+        |> assign(:user, other_user)
+        |> get("/api/v1/pleroma/chats/#{chat.id}/messages")
+
+      assert result |> json_response(404)
+    end
+  end
+
+  describe "POST /api/v1/pleroma/chats/by-account-id/:id" do
+    setup do: oauth_access(["write:chats"])
+
+    test "it creates or returns a chat", %{conn: conn} do
+      other_user = insert(:user)
+
+      result =
+        conn
+        |> post("/api/v1/pleroma/chats/by-account-id/#{other_user.id}")
+        |> json_response_and_validate_schema(200)
+
+      assert result["id"]
+    end
+  end
+
+  describe "GET /api/v1/pleroma/chats/:id" do
+    setup do: oauth_access(["read:chats"])
+
+    test "it returns a chat", %{conn: conn, user: user} do
+      other_user = insert(:user)
+
+      {:ok, chat} = Chat.get_or_create(user.id, other_user.ap_id)
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats/#{chat.id}")
+        |> json_response_and_validate_schema(200)
+
+      assert result["id"] == to_string(chat.id)
+    end
+  end
+
+  describe "GET /api/v1/pleroma/chats" do
+    setup do: oauth_access(["read:chats"])
+
+    test "it does not return chats with users you blocked", %{conn: conn, user: user} do
+      recipient = insert(:user)
+
+      {:ok, _} = Chat.get_or_create(user.id, recipient.ap_id)
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats")
+        |> json_response_and_validate_schema(200)
+
+      assert length(result) == 1
+
+      User.block(user, recipient)
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats")
+        |> json_response_and_validate_schema(200)
+
+      assert length(result) == 0
+    end
+
+    test "it returns all chats", %{conn: conn, user: user} do
+      Enum.each(1..30, fn _ ->
+        recipient = insert(:user)
+        {:ok, _} = Chat.get_or_create(user.id, recipient.ap_id)
+      end)
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats")
+        |> json_response_and_validate_schema(200)
+
+      assert length(result) == 30
+    end
+
+    test "it return a list of chats the current user is participating in, in descending order of updates",
+         %{conn: conn, user: user} do
+      har = insert(:user)
+      jafnhar = insert(:user)
+      tridi = insert(:user)
+
+      {:ok, chat_1} = Chat.get_or_create(user.id, har.ap_id)
+      :timer.sleep(1000)
+      {:ok, _chat_2} = Chat.get_or_create(user.id, jafnhar.ap_id)
+      :timer.sleep(1000)
+      {:ok, chat_3} = Chat.get_or_create(user.id, tridi.ap_id)
+      :timer.sleep(1000)
+
+      # bump the second one
+      {:ok, chat_2} = Chat.bump_or_create(user.id, jafnhar.ap_id)
+
+      result =
+        conn
+        |> get("/api/v1/pleroma/chats")
+        |> json_response_and_validate_schema(200)
+
+      ids = Enum.map(result, & &1["id"])
+
+      assert ids == [
+               chat_2.id |> to_string(),
+               chat_3.id |> to_string(),
+               chat_1.id |> to_string()
+             ]
+    end
+  end
+end
--- a/test/web/pleroma_api/views/chat/message_reference_view_test.exs
+++ b/test/web/pleroma_api/views/chat/message_reference_view_test.exs
@ -0,0 +1,61 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.PleromaAPI.Chat.MessageReferenceViewTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
+  alias Pleroma.Object
+  alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.Web.CommonAPI
+  alias Pleroma.Web.PleromaAPI.Chat.MessageReferenceView
+
+  import Pleroma.Factory
+
+  test "it displays a chat message" do
+    user = insert(:user)
+    recipient = insert(:user)
+
+    file = %Plug.Upload{
+      content_type: "image/jpg",
+      path: Path.absname("test/fixtures/image.jpg"),
+      filename: "an_image.jpg"
+    }
+
+    {:ok, upload} = ActivityPub.upload(file, actor: user.ap_id)
+    {:ok, activity} = CommonAPI.post_chat_message(user, recipient, "kippis :firefox:")
+
+    chat = Chat.get(user.id, recipient.ap_id)
+
+    object = Object.normalize(activity)
+
+    cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+    chat_message = MessageReferenceView.render("show.json", chat_message_reference: cm_ref)
+
+    assert chat_message[:id] == cm_ref.id
+    assert chat_message[:content] == "kippis :firefox:"
+    assert chat_message[:account_id] == user.id
+    assert chat_message[:chat_id]
+    assert chat_message[:created_at]
+    assert chat_message[:unread] == false
+    assert match?([%{shortcode: "firefox"}], chat_message[:emojis])
+
+    {:ok, activity} = CommonAPI.post_chat_message(recipient, user, "gkgkgk", media_id: upload.id)
+
+    object = Object.normalize(activity)
+
+    cm_ref = MessageReference.for_chat_and_object(chat, object)
+
+    chat_message_two = MessageReferenceView.render("show.json", chat_message_reference: cm_ref)
+
+    assert chat_message_two[:id] == cm_ref.id
+    assert chat_message_two[:content] == "gkgkgk"
+    assert chat_message_two[:account_id] == recipient.id
+    assert chat_message_two[:chat_id] == chat_message[:chat_id]
+    assert chat_message_two[:attachment]
+    assert chat_message_two[:unread] == true
+  end
+end
--- a/test/web/pleroma_api/views/chat_view_test.exs
+++ b/test/web/pleroma_api/views/chat_view_test.exs
@ -0,0 +1,48 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.PleromaAPI.ChatViewTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
+  alias Pleroma.Object
+  alias Pleroma.Web.CommonAPI
+  alias Pleroma.Web.CommonAPI.Utils
+  alias Pleroma.Web.MastodonAPI.AccountView
+  alias Pleroma.Web.PleromaAPI.Chat.MessageReferenceView
+  alias Pleroma.Web.PleromaAPI.ChatView
+
+  import Pleroma.Factory
+
+  test "it represents a chat" do
+    user = insert(:user)
+    recipient = insert(:user)
+
+    {:ok, chat} = Chat.get_or_create(user.id, recipient.ap_id)
+
+    represented_chat = ChatView.render("show.json", chat: chat)
+
+    assert represented_chat == %{
+             id: "#{chat.id}",
+             account: AccountView.render("show.json", user: recipient),
+             unread: 0,
+             last_message: nil,
+             updated_at: Utils.to_masto_date(chat.updated_at)
+           }
+
+    {:ok, chat_message_creation} = CommonAPI.post_chat_message(user, recipient, "hello")
+
+    chat_message = Object.normalize(chat_message_creation, false)
+
+    {:ok, chat} = Chat.get_or_create(user.id, recipient.ap_id)
+
+    represented_chat = ChatView.render("show.json", chat: chat)
+
+    cm_ref = MessageReference.for_chat_and_object(chat, chat_message)
+
+    assert represented_chat[:last_message] ==
+             MessageReferenceView.render("show.json", chat_message_reference: cm_ref)
+  end
+end
--- a/test/web/push/impl_test.exs
+++ b/test/web/push/impl_test.exs
@ -5,8 +5,10 @@
 defmodule Pleroma.Web.Push.ImplTest do
  use Pleroma.DataCase

+  alias Pleroma.Notification
  alias Pleroma.Object
  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.ActivityPub
  alias Pleroma.Web.CommonAPI
  alias Pleroma.Web.Push.Impl
  alias Pleroma.Web.Push.Subscription
@ -60,7 +62,8 @@ test "performs sending notifications" do
    notif =
      insert(:notification,
        user: user,
-        activity: activity
+        activity: activity,
+        type: "mention"
      )

    assert Impl.perform(notif) == {:ok, [:ok, :ok]}
@ -126,7 +129,7 @@ test "renders title and body for create activity" do
           ) ==
             "@Bob: Lorem ipsum dolor sit amet, consectetur  adipiscing elit. Fusce sagittis fini..."

-    assert Impl.format_title(%{activity: activity}) ==
+    assert Impl.format_title(%{activity: activity, type: "mention"}) ==
             "New Mention"
  end

@ -136,9 +139,10 @@ test "renders title and body for follow activity" do
    {:ok, _, _, activity} = CommonAPI.follow(user, other_user)
    object = Object.normalize(activity, false)

-    assert Impl.format_body(%{activity: activity}, user, object) == "@Bob has followed you"
+    assert Impl.format_body(%{activity: activity, type: "follow"}, user, object) ==
+             "@Bob has followed you"

-    assert Impl.format_title(%{activity: activity}) ==
+    assert Impl.format_title(%{activity: activity, type: "follow"}) ==
             "New Follower"
  end

@ -157,7 +161,7 @@ test "renders title and body for announce activity" do
    assert Impl.format_body(%{activity: announce_activity}, user, object) ==
             "@#{user.nickname} repeated: Lorem ipsum dolor sit amet, consectetur  adipiscing elit. Fusce sagittis fini..."

-    assert Impl.format_title(%{activity: announce_activity}) ==
+    assert Impl.format_title(%{activity: announce_activity, type: "reblog"}) ==
             "New Repeat"
  end

@ -173,9 +177,10 @@ test "renders title and body for like activity" do
    {:ok, activity} = CommonAPI.favorite(user, activity.id)
    object = Object.normalize(activity)

-    assert Impl.format_body(%{activity: activity}, user, object) == "@Bob has favorited your post"
+    assert Impl.format_body(%{activity: activity, type: "favourite"}, user, object) ==
+             "@Bob has favorited your post"

-    assert Impl.format_title(%{activity: activity}) ==
+    assert Impl.format_title(%{activity: activity, type: "favourite"}) ==
             "New Favorite"
  end

@ -193,6 +198,46 @@ test "renders title for create activity with direct visibility" do
  end

  describe "build_content/3" do
+    test "builds content for chat messages" do
+      user = insert(:user)
+      recipient = insert(:user)
+
+      {:ok, chat} = CommonAPI.post_chat_message(user, recipient, "hey")
+      object = Object.normalize(chat, false)
+      [notification] = Notification.for_user(recipient)
+
+      res = Impl.build_content(notification, user, object)
+
+      assert res == %{
+               body: "@#{user.nickname}: hey",
+               title: "New Chat Message"
+             }
+    end
+
+    test "builds content for chat messages with no content" do
+      user = insert(:user)
+      recipient = insert(:user)
+
+      file = %Plug.Upload{
+        content_type: "image/jpg",
+        path: Path.absname("test/fixtures/image.jpg"),
+        filename: "an_image.jpg"
+      }
+
+      {:ok, upload} = ActivityPub.upload(file, actor: user.ap_id)
+
+      {:ok, chat} = CommonAPI.post_chat_message(user, recipient, nil, media_id: upload.id)
+      object = Object.normalize(chat, false)
+      [notification] = Notification.for_user(recipient)
+
+      res = Impl.build_content(notification, user, object)
+
+      assert res == %{
+               body: "@#{user.nickname}: (Attachment)",
+               title: "New Chat Message"
+             }
+    end
+
    test "hides details for notifications when privacy option enabled" do
      user = insert(:user, nickname: "Bob")
      user2 = insert(:user, nickname: "Rob", notification_settings: %{privacy_option: true})
@ -218,7 +263,7 @@ test "hides details for notifications when privacy option enabled" do
          status: "<Lorem ipsum dolor sit amet."
        })

-      notif = insert(:notification, user: user2, activity: activity)
+      notif = insert(:notification, user: user2, activity: activity, type: "mention")

      actor = User.get_cached_by_ap_id(notif.activity.data["actor"])
      object = Object.normalize(activity)
@ -229,7 +274,7 @@ test "hides details for notifications when privacy option enabled" do

      {:ok, activity} = CommonAPI.favorite(user, activity.id)

-      notif = insert(:notification, user: user2, activity: activity)
+      notif = insert(:notification, user: user2, activity: activity, type: "favourite")

      actor = User.get_cached_by_ap_id(notif.activity.data["actor"])
      object = Object.normalize(activity)
@ -268,7 +313,7 @@ test "returns regular content for notifications with privacy option disabled" do
            "<span>Lorem ipsum dolor sit amet</span>, consectetur :firefox: adipiscing elit. Fusce sagittis finibus turpis."
        })

-      notif = insert(:notification, user: user2, activity: activity)
+      notif = insert(:notification, user: user2, activity: activity, type: "mention")

      actor = User.get_cached_by_ap_id(notif.activity.data["actor"])
      object = Object.normalize(activity)
@ -281,7 +326,7 @@ test "returns regular content for notifications with privacy option disabled" do

      {:ok, activity} = CommonAPI.favorite(user, activity.id)

-      notif = insert(:notification, user: user2, activity: activity)
+      notif = insert(:notification, user: user2, activity: activity, type: "favourite")

      actor = User.get_cached_by_ap_id(notif.activity.data["actor"])
      object = Object.normalize(activity)
--- a/test/web/streamer/streamer_test.exs
+++ b/test/web/streamer/streamer_test.exs
@ -7,11 +7,15 @@ defmodule Pleroma.Web.StreamerTest do

  import Pleroma.Factory

+  alias Pleroma.Chat
+  alias Pleroma.Chat.MessageReference
  alias Pleroma.Conversation.Participation
  alias Pleroma.List
+  alias Pleroma.Object
  alias Pleroma.User
  alias Pleroma.Web.CommonAPI
  alias Pleroma.Web.Streamer
+  alias Pleroma.Web.StreamerView

  @moduletag needs_streamer: true, capture_log: true

@ -145,6 +149,57 @@ test "it sends notify to in the 'user:notification' stream", %{user: user, notif
      refute Streamer.filtered_by_user?(user, notify)
    end

+    test "it sends chat messages to the 'user:pleroma_chat' stream", %{user: user} do
+      other_user = insert(:user)
+
+      {:ok, create_activity} = CommonAPI.post_chat_message(other_user, user, "hey cirno")
+      object = Object.normalize(create_activity, false)
+      chat = Chat.get(user.id, other_user.ap_id)
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+      cm_ref = %{cm_ref | chat: chat, object: object}
+
+      Streamer.get_topic_and_add_socket("user:pleroma_chat", user)
+      Streamer.stream("user:pleroma_chat", {user, cm_ref})
+
+      text = StreamerView.render("chat_update.json", %{chat_message_reference: cm_ref})
+
+      assert text =~ "hey cirno"
+      assert_receive {:text, ^text}
+    end
+
+    test "it sends chat messages to the 'user' stream", %{user: user} do
+      other_user = insert(:user)
+
+      {:ok, create_activity} = CommonAPI.post_chat_message(other_user, user, "hey cirno")
+      object = Object.normalize(create_activity, false)
+      chat = Chat.get(user.id, other_user.ap_id)
+      cm_ref = MessageReference.for_chat_and_object(chat, object)
+      cm_ref = %{cm_ref | chat: chat, object: object}
+
+      Streamer.get_topic_and_add_socket("user", user)
+      Streamer.stream("user", {user, cm_ref})
+
+      text = StreamerView.render("chat_update.json", %{chat_message_reference: cm_ref})
+
+      assert text =~ "hey cirno"
+      assert_receive {:text, ^text}
+    end
+
+    test "it sends chat message notifications to the 'user:notification' stream", %{user: user} do
+      other_user = insert(:user)
+
+      {:ok, create_activity} = CommonAPI.post_chat_message(other_user, user, "hey")
+
+      notify =
+        Repo.get_by(Pleroma.Notification, user_id: user.id, activity_id: create_activity.id)
+        |> Repo.preload(:activity)
+
+      Streamer.get_topic_and_add_socket("user:notification", user)
+      Streamer.stream("user:notification", notify)
+      assert_receive {:render_with_user, _, _, ^notify}
+      refute Streamer.filtered_by_user?(user, notify)
+    end
+
    test "it doesn't send notify to the 'user:notification' stream when a user is blocked", %{
      user: user
    } do