Finish Discord activity implementation

6 files changed, 163 insertions, 38 deletions

diff --git a/lib/mediasync/application.ex b/lib/mediasync/application.ex
index 1e8f6d4..5cef37a 100644
--- a/lib/mediasync/application.ex
+++ b/lib/mediasync/application.ex
@@ -25,6 +25,13 @@ defmodule Mediasync.Application do
       {Registry, keys: :duplicate, name: Mediasync.RoomSubscriptionRegistry}
     ]
 
+    children =
+      if Application.fetch_env!(:mediasync, :enable_discord_activity?) do
+        [{Registry, keys: :duplicate, name: Mediasync.DiscordActivityInstanceRegistry} | children]
+      else
+        children
+      end
+
     System.no_halt(true)
 
     # See https://hexdocs.pm/elixir/Supervisor.html
diff --git a/lib/mediasync/discord_api.ex b/lib/mediasync/discord_api.ex
new file mode 100644
index 0000000..da1d39c
--- /dev/null
+++ b/lib/mediasync/discord_api.ex
@@ -0,0 +1,15 @@
+defmodule Mediasync.DiscordAPI do
+  @base_url "https://discord.com/api/v10/"
+
+  @spec get_user!(String.t()) :: map()
+  def get_user!(access_token) do
+    response =
+      Req.get!(@base_url <> "users/@me", headers: [authorization: "Bearer #{access_token}"])
+
+    if response.status == 200 do
+      response.body
+    else
+      raise "Discord API responded with status code #{response.status}"
+    end
+  end
+end
diff --git a/lib/mediasync/http_errors.ex b/lib/mediasync/http_errors.ex
index c38486a..cbbb613 100644
--- a/lib/mediasync/http_errors.ex
+++ b/lib/mediasync/http_errors.ex
@@ -4,8 +4,8 @@ defmodule Mediasync.HTTPErrors do
 
   @video_url_too_large Jason.encode!(
                          %{
-                           "error" => "video_url_too_large",
-                           "max_size" => Application.compile_env(:mediasync, :max_video_url_size)
+                           "error" => "videoUrlTooLarge",
+                           "maxSize" => Application.compile_env(:mediasync, :max_video_url_size)
                          },
                          pretty: true
                        )
@@ -21,7 +21,7 @@ defmodule Mediasync.HTTPErrors do
     )
   end
 
-  @invalid_video_url Jason.encode!(%{"error" => "invalid_video_url"}, pretty: true)
+  @invalid_video_url Jason.encode!(%{"error" => "invalidVideoUrl"}, pretty: true)
 
   @spec send_invalid_video_url(Plug.Conn.t()) :: Plug.Conn.t()
   @spec send_invalid_video_url(Plug.Conn.t(), []) :: Plug.Conn.t()
@@ -36,7 +36,7 @@ defmodule Mediasync.HTTPErrors do
 
   @not_found Jason.encode!(
                %{
-                 "error" => "not_found",
+                 "error" => "notFound",
                  "message" => "No page was found at this location."
                },
                pretty: true
@@ -68,7 +68,7 @@ defmodule Mediasync.HTTPErrors do
 
   @invalid_csrf_token Jason.encode!(
                         %{
-                          "error" => "invalid_csrf_token",
+                          "error" => "invalidCsrfToken",
                           "message" => "Try reloading the previous page and retrying."
                         },
                         pretty: true
@@ -82,7 +82,29 @@ defmodule Mediasync.HTTPErrors do
     |> send_resp(400, @invalid_csrf_token)
   end
 
-  @bad_gateway Jason.encode!(%{"error" => "bad_gateway"}, pretty: true)
+  @spec send_bad_request(Plug.Conn.t()) :: Plug.Conn.t()
+  @spec send_bad_request(Plug.Conn.t(), message: String.t() | nil) :: Plug.Conn.t()
+  def send_bad_request(conn), do: send_bad_request(conn, message: nil)
+  def send_bad_request(conn, []), do: send_bad_request(conn, message: nil)
+
+  def send_bad_request(conn, message: message) do
+    error = %{
+      "error" => "badRequest"
+    }
+
+    error =
+      if message do
+        Map.put(error, "message", message)
+      else
+        error
+      end
+
+    conn
+    |> put_json_content_type()
+    |> send_resp(400, Jason.encode!(error))
+  end
+
+  @bad_gateway Jason.encode!(%{"error" => "badGateway"}, pretty: true)
 
   @spec send_bad_gateway(Plug.Conn.t()) :: Plug.Conn.t()
   @spec send_bad_gateway(Plug.Conn.t(), []) :: Plug.Conn.t()
diff --git a/lib/mediasync/room.ex b/lib/mediasync/room.ex
index 0367f40..6386893 100644
--- a/lib/mediasync/room.ex
+++ b/lib/mediasync/room.ex
@@ -18,6 +18,9 @@ defmodule Mediasync.Room.State do
     :video_info,
     :host_user_token_hash,
     :room_id,
+    :host_username,
+    :viewer_usernames,
+    :discord_instance_id,
     host_disconnected_tries: @host_disconnected_tries_max
   ]
 
@@ -28,7 +31,10 @@ defmodule Mediasync.Room.State do
   @type t() :: %Mediasync.Room.State{
           video_info: Mediasync.Room.VideoInfo.t(),
           host_user_token_hash: Mediasync.UserToken.hash(),
-          room_id: Mediasync.RoomID.t(),
+          room_id: Mediasync.RoomID.t() | nil,
+          host_username: String.t() | nil,
+          viewer_usernames: [String.t()] | nil,
+          discord_instance_id: String.t() | nil,
           host_disconnected_tries: integer()
         }
 end
@@ -90,10 +96,19 @@ defmodule Mediasync.Room do
 
   @impl true
   @spec init(Mediasync.Room.State.t()) :: {:ok, Mediasync.Room.State.t()}
-  def init(room_state = %Mediasync.Room.State{}) do
+  def init(state = %Mediasync.Room.State{}) do
+    if state.discord_instance_id do
+      Registry.register(Mediasync.DiscordActivityInstanceRegistry, state.discord_instance_id, %{
+        host_username: state.host_username,
+        room_id: state.room_id
+      })
+    end
+
     Process.send_after(self(), :check_if_active, @inactive_check_wait_milliseconds)
 
-    {:ok, room_state}
+    Logger.info("Created room #{state.room_id}")
+
+    {:ok, state}
   end
 
   @impl true
@@ -141,7 +156,7 @@ defmodule Mediasync.Room do
     Process.send_after(self(), :check_if_active, @inactive_check_wait_milliseconds)
 
     if state.host_disconnected_tries <= 0 do
-      Logger.info("Room #{state.room_id} shutting down: no host.")
+      Logger.info("Room #{state.room_id} shutting down: no host")
       {:stop, {:shutdown, :no_host}, state}
     else
       {:noreply, state}
diff --git a/lib/mediasync/router.ex b/lib/mediasync/router.ex
index a27bfc9..c60ca8a 100644
--- a/lib/mediasync/router.ex
+++ b/lib/mediasync/router.ex
@@ -5,7 +5,7 @@ defmodule Mediasync.Router do
   use Plug.Router
   use Plug.ErrorHandler
 
-  plug(Plug.Logger)
+  plug(Plug.Logger, log: :debug)
   plug(Plug.Head)
 
   plug(Plug.Static, at: "/static", from: {:mediasync, "priv/static"})
@@ -34,21 +34,19 @@ defmodule Mediasync.Router do
       conn
       |> put_html_content_type()
 
-    send_resp(
-      conn,
-      200,
-      cond do
-        enable_discord_activity? and Map.get(conn.query_params, query_param_instance_id()) ->
-          Mediasync.Templates.discord_activity()
+    cond do
+      enable_discord_activity? and Map.has_key?(conn.query_params, query_param_instance_id()) ->
+        conn
+        |> put_session("discord_instance_id", conn.query_params["instance_id"])
+        |> send_resp(200, Mediasync.Templates.discord_activity())
 
-        enable_discord_activity? and
-            Map.get(conn.query_params, query_param_discord_activity_inner()) ->
-          Mediasync.Templates.home(:discord_activity)
+      enable_discord_activity? and
+          Map.has_key?(conn.query_params, query_param_discord_activity_inner()) ->
+        send_resp(conn, 200, Mediasync.Templates.home(:discord_activity))
 
-        true ->
-          Mediasync.Templates.home()
-      end
-    )
+      true ->
+        send_resp(conn, 200, Mediasync.Templates.home())
+    end
   end
 
   post "/host_room" do
@@ -73,24 +71,32 @@ defmodule Mediasync.Router do
         Mediasync.HTTPErrors.send_invalid_video_url(conn)
 
       true ->
+        in_discord_activity? =
+          Application.fetch_env!(:mediasync, :enable_discord_activity?) and
+            Map.has_key?(conn.query_params, query_param_discord_activity_inner())
+
+        {suffix, host_username, instance_id} =
+          if in_discord_activity? do
+            {"?#{query_param_discord_activity_inner()}",
+             Mediasync.DiscordAPI.get_user!(get_session(conn, "discord_access_token"))[
+               "username"
+             ], get_session(conn, "discord_instance_id")}
+          else
+            {"", nil, nil}
+          end
+
         {:ok, _pid, room_id} =
           DynamicSupervisor.start_child(
             Mediasync.RoomSupervisor,
             {Mediasync.Room,
              %Mediasync.Room.State{
                video_info: video_info,
-               host_user_token_hash: get_user_token_hash!(conn)
+               host_user_token_hash: get_user_token_hash!(conn),
+               host_username: host_username,
+               discord_instance_id: instance_id
              }}
           )
 
-        suffix =
-          if Application.fetch_env!(:mediasync, :enable_discord_activity?) and
-               Map.get(conn.query_params, query_param_discord_activity_inner()) do
-            "?#{query_param_discord_activity_inner()}"
-          else
-            ""
-          end
-
         redirect(conn, status: 303, location: "/room/#{room_id}#{suffix}")
     end
   end
@@ -104,7 +110,7 @@ defmodule Mediasync.Router do
 
         {video_info, websocket_path, state_url, home_url} =
           if Application.fetch_env!(:mediasync, :enable_discord_activity?) and
-               Map.get(conn.query_params, query_param_discord_activity_inner()) do
+               Map.has_key?(conn.query_params, query_param_discord_activity_inner()) do
             {%{video_info | url: "/.proxy/room/#{room_id}/video"},
              "/.proxy/room/#{room_id}/websocket?#{query_param_discord_activity_inner()}",
              "/.proxy/room/#{room_id}/state.json?#{query_param_discord_activity_inner()}",
@@ -187,6 +193,60 @@ defmodule Mediasync.Router do
     end
   end
 
+  post "/discord_activity/access_token" do
+    if Application.fetch_env!(:mediasync, :enable_discord_activity?) do
+      if Map.has_key?(conn.query_params, query_param_discord_activity_inner()) do
+        response =
+          Req.post!("https://discord.com/api/oauth2/token",
+            headers: [
+              content_type: "application/x-www-form-urlencoded"
+            ],
+            form: [
+              client_id: Application.fetch_env!(:mediasync, :discord_client_id),
+              client_secret: Application.fetch_env!(:mediasync, :discord_client_secret),
+              grant_type: "authorization_code",
+              code: conn.body_params["code"]
+            ]
+          )
+
+        access_token = response.body["access_token"]
+
+        conn
+        |> put_session("discord_access_token", access_token)
+        |> put_plain_text_content_type()
+        |> send_resp(200, access_token)
+      else
+        # If the query param isn't present, we won't be able to modify the session (see session_wrapper/2).
+        Mediasync.HTTPErrors.send_bad_request(conn,
+          message:
+            "This route must always be called with the query param ?#{query_param_discord_activity_inner()}"
+        )
+      end
+    else
+      Mediasync.HTTPErrors.send_not_found(conn)
+    end
+  end
+
+  get "/discord_activity/rooms_for_instance" do
+    if Application.fetch_env!(:mediasync, :enable_discord_activity?) do
+      values =
+        for {_pid, value} <-
+              Registry.match(
+                Mediasync.DiscordActivityInstanceRegistry,
+                conn.query_params["instance_id"],
+                :_
+              ) do
+          value
+        end
+
+      conn
+      |> put_json_content_type()
+      |> send_resp(200, Jason.encode!(values))
+    else
+      Mediasync.HTTPErrors.send_not_found(conn)
+    end
+  end
+
   match _ do
     Mediasync.HTTPErrors.send_not_found(conn)
   end
@@ -206,10 +266,10 @@ defmodule Mediasync.Router do
     query_params = fetch_query_params(conn).query_params
 
     in_discord_activity? =
-      !!(Application.fetch_env!(:mediasync, :enable_discord_activity?) &&
-           (Map.get(query_params, query_param_discord_activity_inner()) ||
-              (conn.request_path == "/" &&
-                 Map.get(query_params, query_param_instance_id()))))
+      Application.fetch_env!(:mediasync, :enable_discord_activity?) and
+        (Map.has_key?(query_params, query_param_discord_activity_inner()) or
+           (conn.request_path == "/" and
+              Map.has_key?(query_params, query_param_instance_id())))
 
     Plug.Session.call(
       conn,
diff --git a/lib/mediasync/utils.ex b/lib/mediasync/utils.ex
index 407a9a4..c2f3531 100644
--- a/lib/mediasync/utils.ex
+++ b/lib/mediasync/utils.ex
@@ -13,6 +13,12 @@ defmodule Mediasync.Utils do
     put_resp_content_type(conn, "application/json")
   end
 
+  @spec put_plain_text_content_type(Plug.Conn.t()) :: Plug.Conn.t()
+  @spec put_plain_text_content_type(Plug.Conn.t(), []) :: Plug.Conn.t()
+  def put_plain_text_content_type(conn, _opts \\ []) do
+    put_resp_content_type(conn, "text/plain")
+  end
+
   @spec redirect(Plug.Conn.t(), status: Plug.Conn.status(), location: binary()) :: Plug.Conn.t()
   def redirect(conn, status: status, location: location) do
     conn