# Extends the stamping functionality of ActiveRecord by automatically recording the model
# responsible for creating, updating, and deleting the current object. See the +Stamper+ and
# +ControllerAdditions+ modules for further documentation on how the entire process works.
module ActiveRecord::Userstamp::Stampable
  extend ActiveSupport::Concern

  included do
    # Should ActiveRecord record userstamps? Defaults to true.
    class_attribute  :record_userstamp
    self.record_userstamp = true

    class_attribute  :stamper_class_name

    before_validation :set_updater_attribute, if: :record_userstamp
    before_validation :set_creator_attribute, on: :create, if: :record_userstamp
    before_save :set_updater_attribute, if: :record_userstamp
    before_save :set_creator_attribute, on: :create, if: :record_userstamp
    before_destroy :set_deleter_attribute, if: :record_userstamp
  end

  module ClassMethods
    def inherited(klass)
      super

      klass.class_eval do
        add_userstamp_associations({})
      end
    end

    # This method customizes how the gem functions. For example:
    #
    #   class Post < ActiveRecord::Base
    #     stampable stamper_class_name: Person.name,
    #               with_deleted:       true
    #   end
    #
    # The method will set up all the associations. Extra arguments (like +:with_deleted+) will be
    # propagated to the associations.
    #
    # By default, the deleter association is not defined unless the :deleter_attribute is set in
    # the gem configuration.
    def stampable(options = {})
      self.stamper_class_name = options.delete(:stamper_class_name) if options.key?(:stamper_class_name)

      add_userstamp_associations(options)
    end

    # Temporarily allows you to turn stamping off. For example:
    #
    #   Post.without_stamps do
    #     post = Post.find(params[:id])
    #     post.update_attributes(params[:post])
    #     post.save
    #   end
    def without_stamps
      original_value = self.record_userstamp
      self.record_userstamp = false
      yield
    ensure
      self.record_userstamp = original_value
    end

    def stamper_class #:nodoc:
      stamper_class_name.to_s.camelize.constantize rescue nil
    end

    private

    # Defines the associations for Userstamp.
    def add_userstamp_associations(options)
      ActiveRecord::Userstamp::Utilities.remove_association(self, :creator)
      ActiveRecord::Userstamp::Utilities.remove_association(self, :updater)
      ActiveRecord::Userstamp::Utilities.remove_association(self, :deleter)

      associations = ActiveRecord::Userstamp::Utilities.available_association_columns(self)
      return if associations.nil?

      config = ActiveRecord::Userstamp.config
      klass = stamper_class.try(:name)
      relation_options = options.reverse_merge(class_name: klass)

      belongs_to :creator, relation_options.reverse_merge(foreign_key: config.creator_attribute) if
        associations.first
      belongs_to :updater, relation_options.reverse_merge(foreign_key: config.updater_attribute) if
        associations.second
      belongs_to :deleter, relation_options.reverse_merge(foreign_key: config.deleter_attribute) if
        associations.third
    end
  end

  private

  def has_stamper?
    !self.class.stamper_class.nil? && !self.class.stamper_class.stamper.nil?
  end

  def set_creator_attribute
    creator_attribute = ActiveRecord::Userstamp.config.creator_attribute
    return if !has_stamper? || creator_attribute.nil? || !has_attribute?(creator_attribute)

    current_attribute_value = send(creator_attribute)
    return if current_attribute_value.present?

    send("#{creator_attribute}=", self.class.stamper_class.stamper)
  end

  def set_updater_attribute
    updater_attribute = ActiveRecord::Userstamp.config.updater_attribute
    return if !has_stamper? || updater_attribute.nil? || !has_attribute?(updater_attribute)

    return if !self.new_record? && !self.changed?

    send("#{updater_attribute}=", self.class.stamper_class.stamper)
  end

  def set_deleter_attribute
    deleter_attribute = ActiveRecord::Userstamp.config.deleter_attribute
    return if !has_stamper? || deleter_attribute.nil? || !has_attribute?(deleter_attribute)

    send("#{deleter_attribute}=", self.class.stamper_class.stamper)
    save
  end
end