Lists (#5703)

* Add structure for lists

* Add list timeline streaming API

* Add list APIs, bind list-account relation to follow relation

* Add API for adding/removing accounts from lists

* Add pagination to lists API

* Add pagination to list accounts API

* Adjust scopes for new APIs

- Creating and modifying lists merely requires "write" scope
- Fetching information about lists merely requires "read" scope

* Add test for wrong user context on list timeline

* Clean up tests

app/controllers/api/v1/timelines/home_controller.rb

@@ -31,7 +31,7 @@ class Api::V1::Timelines::HomeController < Api::BaseController
   end
 
   def account_home_feed
-    Feed.new(:home, current_account)
+    HomeFeed.new(current_account)
   end
 
   def insert_pagination_headers

app/controllers/api/v1/timelines/list_controller.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+class Api::V1::Timelines::ListController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :read }
+  before_action :require_user!
+  before_action :set_list
+  before_action :set_statuses
+
+  after_action :insert_pagination_headers, unless: -> { @statuses.empty? }
+
+  def show
+    render json: @statuses,
+           each_serializer: REST::StatusSerializer,
+           relationships: StatusRelationshipsPresenter.new(@statuses, current_user.account_id)
+  end
+
+  private
+
+  def set_list
+    @list = List.where(account: current_account).find(params[:id])
+  end
+
+  def set_statuses
+    @statuses = cached_list_statuses
+  end
+
+  def cached_list_statuses
+    cache_collection list_statuses, Status
+  end
+
+  def list_statuses
+    list_feed.get(
+      limit_param(DEFAULT_STATUSES_LIMIT),
+      params[:max_id],
+      params[:since_id]
+    )
+  end
+
+  def list_feed
+    ListFeed.new(@list)
+  end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def pagination_params(core_params)
+    params.permit(:limit).merge(core_params)
+  end
+
+  def next_path
+    api_v1_timelines_list_url params[:id], pagination_params(max_id: pagination_max_id)
+  end
+
+  def prev_path
+    api_v1_timelines_list_url params[:id], pagination_params(since_id: pagination_since_id)
+  end
+
+  def pagination_max_id
+    @statuses.last.id
+  end
+
+  def pagination_since_id
+    @statuses.first.id
+  end
+end