module GoodJob
  class Job < ActiveRecord::Base
    include Lockable

    PreviouslyPerformedError = Class.new(StandardError)

    DEFAULT_QUEUE_NAME = 'default'.freeze
    DEFAULT_PRIORITY = 0

    self.table_name = 'good_jobs'.freeze

    scope :unfinished, (lambda do
      if column_names.include?('finished_at')
        where(finished_at: nil)
      else
        ActiveSupport::Deprecation.warn('GoodJob expects a good_jobs.finished_at column to exist. Please see the GoodJob README.md for migration instructions.')
        nil
      end
    end)
    scope :only_scheduled, -> { where(arel_table['scheduled_at'].lteq(Time.current)).or(where(scheduled_at: nil)) }
    scope :priority_ordered, -> { order(priority: :desc) }
    scope :finished, ->(timestamp = nil) { timestamp ? where(arel_table['finished_at'].lteq(timestamp)) : where.not(finished_at: nil) }

    def self.perform_with_advisory_lock(destroy_after: !GoodJob.preserve_job_records)
      good_job = nil
      result = nil
      error = nil

      unfinished.only_scheduled.limit(1).with_advisory_lock do |good_jobs|
        good_job = good_jobs.first
        break unless good_job

        result, error = good_job.perform(destroy_after: destroy_after)
      end

      [good_job, result, error] if good_job
    end

    def self.perform_with_advisory_lock_and_preserve_job_records
      perform_with_advisory_lock(destroy_after: false)
    end

    def self.perform_with_advisory_lock_and_destroy_job_records
      perform_with_advisory_lock(destroy_after: true)
    end

    def self.enqueue(active_job, scheduled_at: nil, create_with_advisory_lock: false)
      good_job = nil
      ActiveSupport::Notifications.instrument("enqueue_job.good_job", { active_job: active_job, scheduled_at: scheduled_at, create_with_advisory_lock: create_with_advisory_lock }) do |instrument_payload|
        good_job = GoodJob::Job.new(
          queue_name: active_job.queue_name.presence || DEFAULT_QUEUE_NAME,
          priority: active_job.priority || DEFAULT_PRIORITY,
          serialized_params: active_job.serialize,
          scheduled_at: scheduled_at || Time.current,
          create_with_advisory_lock: create_with_advisory_lock
        )

        instrument_payload[:good_job] = good_job

        good_job.save!
        active_job.provider_job_id = good_job.id
      end

      good_job
    end

    def perform(destroy_after: true)
      raise PreviouslyPerformedError, 'Cannot perform a job that has already been performed' if finished_at

      result = nil
      error = nil

      ActiveSupport::Notifications.instrument("before_perform_job.good_job", { good_job: self })
      self.performed_at = Time.current
      save! unless destroy_after

      ActiveSupport::Notifications.instrument("perform_job.good_job", { good_job: self }) do
        params = serialized_params.merge(
          "provider_job_id" => id
        )
        begin
          result = ActiveJob::Base.execute(params)
        rescue StandardError => e
          error = e
        end
      end

      if error.nil? && result.is_a?(Exception)
        error = result
        result = nil
      end

      error_message = "#{error.class}: #{error.message}" if error
      self.error = error_message
      self.finished_at = Time.current

      if destroy_after
        destroy!
      else
        save!
      end

      [result, error]
    end
  end
end