Chats: Introduce /api/v2/pleroma/chats which implements pagination

Also removes incorrect claim that /api/v1/pleroma/chats supports
pagination and deprecates it.

Closes #2140

lib/pleroma/web/api_spec/operations/chat_operation.ex

@@ -131,8 +131,30 @@ defmodule Pleroma.Web.ApiSpec.ChatOperation do
   def index_operation do
     %Operation{
       tags: ["Chats"],
-      summary: "Retrieve list of chats",
+      summary: "Retrieve list of chats (unpaginated)",
+      deprecated: true,
+      description:
+        "Deprecated due to no support for pagination. Using [/api/v2/pleroma/chats](#operation/ChatController.index2) instead is recommended.",
       operationId: "ChatController.index",
+      parameters: [
+        Operation.parameter(:with_muted, :query, BooleanLike, "Include chats from muted users")
+      ],
+      responses: %{
+        200 => Operation.response("The chats of the user", "application/json", chats_response())
+      },
+      security: [
+        %{
+          "oAuth" => ["read:chats"]
+        }
+      ]
+    }
+  end
+
+  def index2_operation do
+    %Operation{
+      tags: ["Chats"],
+      summary: "Retrieve list of chats",
+      operationId: "ChatController.index2",
       parameters: [
         Operation.parameter(:with_muted, :query, BooleanLike, "Include chats from muted users")
         | pagination_params()

lib/pleroma/web/pleroma_api/controllers/chat_controller.ex

@@ -35,7 +35,7 @@ defmodule Pleroma.Web.PleromaAPI.ChatController do
 
   plug(
     OAuthScopesPlug,
-    %{scopes: ["read:chats"]} when action in [:messages, :index, :show]
+    %{scopes: ["read:chats"]} when action in [:messages, :index, :index2, :show]
   )
 
   plug(OpenApiSpex.Plug.CastAndValidate, render_error: Pleroma.Web.ApiSpec.RenderError)
@@ -138,18 +138,30 @@ defmodule Pleroma.Web.PleromaAPI.ChatController do
     end
   end
 
-  def index(%{assigns: %{user: %{id: user_id} = user}} = conn, params) do
+  def index(%{assigns: %{user: user}} = conn, params) do
+    chats =
+      index_query(user, params)
+      |> Repo.all()
+
+    render(conn, "index.json", chats: chats)
+  end
+
+  def index2(%{assigns: %{user: user}} = conn, params) do
+    chats =
+      index_query(user, params)
+      |> Pagination.fetch_paginated(params)
+
+    render(conn, "index.json", chats: chats)
+  end
+
+  defp index_query(%{id: user_id} = user, params) do
     exclude_users =
       User.cached_blocked_users_ap_ids(user) ++
         if params[:with_muted], do: [], else: User.cached_muted_users_ap_ids(user)
 
-    chats =
-      user_id
-      |> Chat.for_user_query()
-      |> where([c], c.recipient not in ^exclude_users)
-      |> Repo.all()
-
-    render(conn, "index.json", chats: chats)
+    user_id
+    |> Chat.for_user_query()
+    |> where([c], c.recipient not in ^exclude_users)
   end
 
   def create(%{assigns: %{user: user}} = conn, %{id: id}) do

lib/pleroma/web/router.ex

@@ -411,6 +411,13 @@ defmodule Pleroma.Web.Router do
     get("/federation_status", InstancesController, :show)
   end
 
+  scope "/api/v2/pleroma", Pleroma.Web.PleromaAPI do
+    scope [] do
+      pipe_through(:authenticated_api)
+      get("/chats", ChatController, :index2)
+    end
+  end
+
   scope "/api/v1", Pleroma.Web.MastodonAPI do
     pipe_through(:authenticated_api)