mastodon/app/models/favourite.rb

# frozen_string_literal: true
# == Schema Information
#
# Table name: favourites
#
#  id         :bigint(8)        not null, primary key
#  created_at :datetime         not null
#  updated_at :datetime         not null
#  account_id :bigint(8)        not null
#  status_id  :bigint(8)        not null
#

class Favourite < ApplicationRecord
  include Paginable

  update_index('statuses#status', :status) if Chewy.enabled?

  belongs_to :account, inverse_of: :favourites
  belongs_to :status,  inverse_of: :favourites

  has_one :notification, as: :activity, dependent: :destroy

  validates :status_id, uniqueness: { scope: :account_id }

  before_validation do
    self.status = status.reblog if status&.reblog?
  end

  after_create :increment_cache_counters
  after_destroy :decrement_cache_counters

  private

  def increment_cache_counters
    if association(:status).loaded?
      status.update_attribute(:favourites_count, status.favourites_count + 1)
    else
      Status.where(id: status_id).update_all('favourites_count = COALESCE(favourites_count, 0) + 1')
    end
  end

  def decrement_cache_counters
    return if association(:status).loaded? && (status.marked_for_destruction? || status.marked_for_mass_destruction?)

    if association(:status).loaded?
      status.update_attribute(:favourites_count, [status.favourites_count - 1, 0].max)
    else
      Status.where(id: status_id).update_all('favourites_count = GREATEST(COALESCE(favourites_count, 0) - 1, 0)')
    end
  end
end