Draft API to create Collections (#37049)

app/controllers/api/v1_alpha/collections_controller.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+class Api::V1Alpha::CollectionsController < Api::BaseController
+  rescue_from ActiveRecord::RecordInvalid, Mastodon::ValidationError do |e|
+    render json: { error: ValidationErrorFormatter.new(e).as_json }, status: 422
+  end
+
+  before_action :check_feature_enabled
+
+  before_action -> { doorkeeper_authorize! :write, :'write:collections' }, only: [:create]
+
+  before_action :require_user!
+
+  def create
+    @collection = CreateCollectionService.new.call(collection_params, current_user.account)
+
+    render json: @collection, serializer: REST::CollectionSerializer
+  end
+
+  private
+
+  def collection_params
+    params.permit(:name, :description, :sensitive, :discoverable, :tag, account_ids: [])
+  end
+
+  def check_feature_enabled
+    raise ActionController::RoutingError unless Mastodon::Feature.collections_enabled?
+  end
+end