From c181e555db4a90f770418af67b1073ec958adb4d Mon Sep 17 00:00:00 2001
From: Ivan Tashkinov <ivantashkinov@gmail.com>
Date: Fri, 29 May 2020 22:03:14 +0300
Subject: [PATCH] [#1794] Improvements to hashtags extraction from search
 query.

---
 .../controllers/search_controller.ex          | 40 ++++++++++++++-----
 .../controllers/search_controller_test.exs    | 36 ++++++++++++++++-
 2 files changed, 66 insertions(+), 10 deletions(-)

diff --git a/lib/pleroma/web/mastodon_api/controllers/search_controller.ex b/lib/pleroma/web/mastodon_api/controllers/search_controller.ex
index 77e2224e4..23fe378a6 100644
--- a/lib/pleroma/web/mastodon_api/controllers/search_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/search_controller.ex
@@ -113,22 +113,44 @@ defp resource_search(:v2, "hashtags", query, _options) do
     query
     |> prepare_tags()
     |> Enum.map(fn tag ->
-      tag = String.trim_leading(tag, "#")
       %{name: tag, url: tags_path <> tag}
     end)
   end
 
   defp resource_search(:v1, "hashtags", query, _options) do
-    query
-    |> prepare_tags()
-    |> Enum.map(fn tag -> String.trim_leading(tag, "#") end)
+    prepare_tags(query)
   end
 
-  defp prepare_tags(query) do
-    query
-    |> String.split()
-    |> Enum.uniq()
-    |> Enum.filter(fn tag -> String.starts_with?(tag, "#") end)
+  defp prepare_tags(query, add_joined_tag \\ true) do
+    tags =
+      query
+      |> String.split(~r/[^#\w]+/, trim: true)
+      |> Enum.uniq_by(&String.downcase/1)
+
+    explicit_tags = Enum.filter(tags, fn tag -> String.starts_with?(tag, "#") end)
+
+    tags =
+      if Enum.any?(explicit_tags) do
+        explicit_tags
+      else
+        tags
+      end
+
+    tags = Enum.map(tags, fn tag -> String.trim_leading(tag, "#") end)
+
+    if Enum.empty?(explicit_tags) && add_joined_tag do
+      tags
+      |> Kernel.++([joined_tag(tags)])
+      |> Enum.uniq_by(&String.downcase/1)
+    else
+      tags
+    end
+  end
+
+  defp joined_tag(tags) do
+    tags
+    |> Enum.map(fn tag -> String.capitalize(tag) end)
+    |> Enum.join()
   end
 
   defp with_fallback(f, fallback \\ []) do
diff --git a/test/web/mastodon_api/controllers/search_controller_test.exs b/test/web/mastodon_api/controllers/search_controller_test.exs
index 7d0cafccc..498290377 100644
--- a/test/web/mastodon_api/controllers/search_controller_test.exs
+++ b/test/web/mastodon_api/controllers/search_controller_test.exs
@@ -75,6 +75,40 @@ test "search", %{conn: conn} do
       assert status["id"] == to_string(activity.id)
     end
 
+    test "constructs hashtags from search query", %{conn: conn} do
+      results =
+        conn
+        |> get("/api/v2/search?#{URI.encode_query(%{q: "some text with #explicit #hashtags"})}")
+        |> json_response_and_validate_schema(200)
+
+      assert results["hashtags"] == [
+               %{"name" => "explicit", "url" => "#{Web.base_url()}/tag/explicit"},
+               %{"name" => "hashtags", "url" => "#{Web.base_url()}/tag/hashtags"}
+             ]
+
+      results =
+        conn
+        |> get("/api/v2/search?#{URI.encode_query(%{q: "john doe JOHN DOE"})}")
+        |> json_response_and_validate_schema(200)
+
+      assert results["hashtags"] == [
+               %{"name" => "john", "url" => "#{Web.base_url()}/tag/john"},
+               %{"name" => "doe", "url" => "#{Web.base_url()}/tag/doe"},
+               %{"name" => "JohnDoe", "url" => "#{Web.base_url()}/tag/JohnDoe"}
+             ]
+
+      results =
+        conn
+        |> get("/api/v2/search?#{URI.encode_query(%{q: "accident-prone"})}")
+        |> json_response_and_validate_schema(200)
+
+      assert results["hashtags"] == [
+               %{"name" => "accident", "url" => "#{Web.base_url()}/tag/accident"},
+               %{"name" => "prone", "url" => "#{Web.base_url()}/tag/prone"},
+               %{"name" => "AccidentProne", "url" => "#{Web.base_url()}/tag/AccidentProne"}
+             ]
+    end
+
     test "excludes a blocked users from search results", %{conn: conn} do
       user = insert(:user)
       user_smith = insert(:user, %{nickname: "Agent", name: "I love 2hu"})
@@ -179,7 +213,7 @@ test "search", %{conn: conn} do
       [account | _] = results["accounts"]
       assert account["id"] == to_string(user_three.id)
 
-      assert results["hashtags"] == []
+      assert results["hashtags"] == ["2hu"]
 
       [status] = results["statuses"]
       assert status["id"] == to_string(activity.id)