# Copyright (C) 2012-2024 Zammad Foundation, https://zammad-foundation.org/

class Sequencer::Unit::Import::Common::Model::Associations::Assign < Sequencer::Unit::Base
  include ::Sequencer::Unit::Import::Common::Model::Mixin::HandleFailure

  uses :instance, :associations, :action, :dry_run
  provides :action

  def process
    return if dry_run
    return if instance.blank?
    return if associations.blank? && log_associations_error

    register_changes
    instance.assign_attributes(associations)
  rescue => e
    handle_failure(e)
  end

  private

  # always returns true
  def log_associations_error
    return true if %i[skipped failed deactivated].include?(action)

    logger.error { 'associations cannot be nil' } if associations.nil?
    true
  end

  def register_changes
    return if !(action == :unchanged && changes.any?)

    logger.debug { "Changed instance associations: #{changes.inspect}" }
    state.provide(:action, :updated)
  end

  # Why not just use instance.changes?
  # Because it doesn't include associations
  # stored on OTHER TABLES (has-one, has-many, HABTM)
  def changes
    @changes ||= unfiltered_changes.reject { |_attribute, values| no_diff?(values) }
  end

  def unfiltered_changes
    attrs  = associations.keys
    before = attrs.map { |attribute| instance.send(attribute) }
    after  = associations.values
    attrs.zip(before.zip(after)).to_h.with_indifferent_access
  end

  def no_diff?(values)
    values.map!(&:sort) if values.all? { |val| val.respond_to?(:sort) }
    values.map!(&:presence) # [nil, []] -> [nil, nil]
    values.uniq.length == 1
  end
end