mastodon/app/controllers/api_controller.rb

class ApiController < ApplicationController
  protect_from_forgery with: :null_session
  skip_before_action :verify_authenticity_token

  rescue_from ActiveRecord::RecordInvalid do |e|
    render json: { error: e.to_s }, status: 422
  end

  rescue_from ActiveRecord::RecordNotFound do
    render json: { error: 'Record not found' }, status: 404
  end

  rescue_from Goldfinger::Error do
    render json: { error: 'Remote account could not be resolved' }, status: 422
  end

  rescue_from HTTP::Error do
    render json: { error: 'Remote data could not be fetched' }, status: 503
  end

  rescue_from OpenSSL::SSL::SSLError do
    render json: { error: 'Remote SSL certificate could not be verified' }, status: 503
  end

  protected

  def current_resource_owner
    User.find(doorkeeper_token.resource_owner_id) if doorkeeper_token
  end

  def current_user
    super || current_resource_owner
  end

  def render_empty
    render json: {}, status: 200
  end

  def set_maps(statuses)
    status_ids      = statuses.flat_map { |s| [s.id, s.reblog_of_id] }.compact.uniq
    @reblogs_map    = Status.reblogs_map(status_ids, current_user.account)
    @favourites_map = Status.favourites_map(status_ids, current_user.account)
  end
end