require 'set'
require 'notifiably_audited/audit'

module NotifiablyAudited
  module Adapters
    module ActiveRecord
      # Audit saves the changes to ActiveRecord models.  It has the following attributes:
      #
      # * <tt>auditable</tt>: the ActiveRecord model that was changed
      # * <tt>user</tt>: the user that performed the change; a string or an ActiveRecord model
      # * <tt>action</tt>: one of create, update, or delete
      # * <tt>audited_changes</tt>: a serialized hash of all the changes
      # * <tt>comment</tt>: a comment set with the audit
      # * <tt>created_at</tt>: Time that the change was performed
      #
      class Audit < ::ActiveRecord::Base
        include NotifiablyAudited::Audit


        serialize :audited_changes

        default_scope         order(:version)
        scope :descending,    reorder("version DESC")
        scope :creates,       :conditions => {:action => 'create'}
        scope :updates,       :conditions => {:action => 'update'}
        scope :destroys,      :conditions => {:action => 'destroy'}

        scope :up_until,      lambda {|date_or_time| where("created_at <= ?", date_or_time) }
        scope :from_version,  lambda {|version| where(['version >= ?', version]) }
        scope :to_version,    lambda {|version| where(['version <= ?', version]) }

        # Return all audits older than the current one.
        def ancestors
          self.class.where(['auditable_id = ? and auditable_type = ? and version <= ?',
            auditable_id, auditable_type, version])
        end

        # Allows user to be set to either a string or an ActiveRecord object
        # @private
        def user_as_string=(user)
          # reset both either way
          self.user_as_model = self.username = nil
          user.is_a?(::ActiveRecord::Base) ?
            self.user_as_model = user :
            self.username = user
        end
        alias_method :user_as_model=, :user=
        alias_method :user=, :user_as_string=

        # @private
        def user_as_string
          self.user_as_model || self.username
        end
        alias_method :user_as_model, :user
        alias_method :user, :user_as_string

      private
        def set_version_number
          max = self.class.maximum(:version,
            :conditions => {
              :auditable_id => auditable_id,
              :auditable_type => auditable_type
            }) || 0
          self.version = max + 1
        end
      end
    end
  end
end