//! Client for download management.

use std::collections::BTreeMap;
use std::convert::TryInto;
use std::time::Duration;

use serde::Serialize;

use tokio::time::sleep;

use crate::Error;
mod payload;
use payload::Request;
use payload::Response;
mod list;
use list::FieldList;
use list::TorrentList;
pub mod torrent;
use torrent::Torrent;
use torrent::TorrentFile;
use torrent::AddTorrent;
use torrent::AddTorrentResponse;
use torrent::GetTorrentFilesRequest;
use torrent::GetTorrentFilesResponse;
//use torrent::AddedTorrent;

/// Interface into the major functions of Transmission
/// including adding, and removing torrents.
///
/// The `Client` does not keep track of the created torrents itself.
/// ```
#[derive(Clone)]
pub struct Client {
	host: String,
	port: u16,
	tls: bool,
	auth: Option<(String, String)>,

	base_url: String,
	session_id: Option<String>,

	http: reqwest::Client,
}

impl Client {
	// TODO:  Take Option<(&str, &str)> for auth
	pub fn new(host: impl ToString, port: u16, tls: bool, auth: Option<(String, String)>) -> Result<Self, Error> {
		let mut headers = reqwest::header::HeaderMap::new();
		headers.insert(reqwest::header::USER_AGENT, "transmission-rs/0.1".try_into()?);
		let this = Self{
			host: host.to_string(),
			port: port,
			tls: tls,
			auth: auth,
			base_url: {
				let protocol = match tls {
					true => "https",
					false => "http"
				};
				format!("{}://{}:{}", protocol, host.to_string(), port)
			},
			session_id: None,
			http: reqwest::Client::builder()
				.gzip(true)
				.default_headers(headers)
				.build()?
		};
		Ok(this)
	}

	fn build_url(&self, path: impl AsRef<str>) -> String {
		format!("{}{}", self.base_url, path.as_ref()).to_string()
	}

	pub async fn authenticate(&mut self) -> Result<(), Error> {
		self.session_id = None;
		let response = self.post("/transmission/rpc/")
			.header("Content-Type", "application/x-www-form-urlencoded")
			.send()
			.await?;
		self.session_id = match response.headers().get("X-Transmission-Session-Id") {
			Some(v) => Some(v.to_str()?.to_string()),
			None => None // TODO:  Return an error
		};
		Ok(())
	}

	pub fn post(&self, path: impl AsRef<str>) -> reqwest::RequestBuilder {
		let url = self.build_url(path);
		//println!("{}", url);
		let mut request = self.http.post(&url);
		request = match &self.auth {
			Some(auth) => request.basic_auth(&auth.0, Some(&auth.1)),
			None => request
		};
		request = match &self.session_id {
			Some(token) => request.header("X-Transmission-Session-Id", token),
			None => request
		};
		request
	}

	pub async fn rpc(&mut self, method: impl ToString, tag: u8, body: impl Serialize) -> Result<reqwest::Response, Error> {
		let request = Request::new(method, tag, body);
		let mut error = None;
		for i in 0..5 {
			sleep(Duration::from_secs(i)).await;
			let result = self.post("/transmission/rpc/")
				// Content-Type doesn't actually appear to be necessary, and is
				//    technically a lie, since there's no key/value being passed,
				//    just some JSON, but the official client sends this, so we
				//    will too.
				.header("Content-Type", "application/x-www-form-urlencoded")
				.body(serde_json::to_string(&request)?)
				.send().await?
				.error_for_status();
			match result {
				Ok(r) => return Ok(r),
				Err(e) => match e.status() {
					Some(reqwest::StatusCode::CONFLICT) => {
						self.authenticate().await?;
						error = Some(e);
						continue;
					},
					_ => return Err(e.into())
				}
			};
		}
		match error {
			Some(e) => Err(e.into()),
			// Should be unreachable
			None => Err(Error::HTTPUnknown)
		}
	}

	pub async fn list(&mut self) -> Result<Vec<Torrent>, Error> {
		let field_list = FieldList::from_vec(vec![
			"error",
			"errorString",
			"eta",
			"id",
			"isFinished",
			"leftUntilDone",
			"name",
			"peersGettingFromUs",
			"peersSendingToUs",
			"rateDownload",
			"rateUpload",
			"sizeWhenDone",
			"status",
			"uploadRatio"
		]);
		let response: Response<TorrentList> = self.rpc("torrent-get", 4, field_list).await?.error_for_status()?.json().await?;
		Ok(response.arguments.torrents)
	}

	// TODO:  Borrow key from value
	pub async fn list_by_name(&mut self) -> Result<BTreeMap<String, Torrent>, Error> {
		Ok(self.list().await?.into_iter().map(|v| (v.name.clone(), v)).collect::<BTreeMap<_, _>>())
	}

	pub async fn add_torrent_from_link(&mut self, url: impl ToString) -> Result<AddTorrentResponse, Error> {
		let response: Response<AddTorrentResponse> = self.rpc("torrent-add", 8, AddTorrent{filename: url.to_string()}).await?.error_for_status()?.json().await?;
		Ok(response.arguments)
	}

	pub async fn get_files_by_id(&mut self, id: u16) -> Result<Vec<TorrentFile>, Error> {
		let response: Response<GetTorrentFilesResponse> = self.rpc("torrent-get", 3, GetTorrentFilesRequest::new(id)).await?.error_for_status()?.json().await?;
		if(response.arguments.torrents.len() == 0) {
			// TODO:  Maybe make the Ok result an Option?  Or maybe return a 404 error?
			return Ok(vec![]);
		} else if(response.arguments.torrents.len() > 1) {
			return Err(Error::WeirdGetFilesResponse);
		}
		// TODO:  Figure out how to move files out of this structure, since we're discarding the rest anyway, instead of cloning
		Ok(response.arguments.torrents[0].files.clone())
	}
}