module Syncable
  extend ActiveSupport::Concern

  included do
    has_many :syncs, as: :syncable, dependent: :destroy
  end

  def syncing?
    raise NotImplementedError, "Subclasses must implement the syncing? method"
  end

  # Schedules a sync for syncable.  If there is an existing sync pending/syncing for this syncable,
  # we do not create a new sync, and attempt to expand the sync window if needed.
  def sync_later(parent_sync: nil, window_start_date: nil, window_end_date: nil)
    Sync.transaction do
      with_lock do
        sync = self.syncs.incomplete.first

        if sync
          Rails.logger.info("There is an existing sync, expanding window if needed (#{sync.id})")
          sync.expand_window_if_needed(window_start_date, window_end_date)
        else
          sync = self.syncs.create!(
            parent: parent_sync,
            window_start_date: window_start_date,
            window_end_date: window_end_date
          )

          SyncJob.perform_later(sync)
        end

        sync
      end
    end
  end

  def perform_sync(sync)
    syncer.perform_sync(sync)
  end

  def perform_post_sync
    syncer.perform_post_sync
  end

  def broadcast_sync_complete
    sync_broadcaster.broadcast
  end

  def sync_error
    latest_sync&.error
  end

  def last_synced_at
    latest_sync&.completed_at
  end

  def last_sync_created_at
    latest_sync&.created_at
  end

  private
    def latest_sync
      syncs.ordered.first
    end

    def syncer
      self.class::Syncer.new(self)
    end

    def sync_broadcaster
      self.class::SyncCompleteEvent.new(self)
    end
end