#   Copyright (c) 2010, Diaspora Inc.  This file is
#   licensed under the Affero General Public License version 3 or later.  See
#   the COPYRIGHT file.

module Diaspora
  module Relayable
    include Encryptable

    def self.included(model)
      model.class_eval do
        #these fields must be in the schema for a relayable model
        xml_attr :parent_guid
        xml_attr :parent_author_signature
        xml_attr :author_signature
      end
    end

    def relayable?
      true
    end

    def parent_guid
      self.parent.guid
    end

    def parent_guid= new_parent_guid
      self.parent = parent_class.where(:guid => new_parent_guid).first
    end

    def subscribers(user)
      if user.owns?(self.parent)
        self.parent.subscribers(user)
      elsif user.owns?(self)
        [self.parent.author]
      end
    end

    def receive(user, person)
      object = self.class.where(:guid => self.guid).first || self

      unless object.parent.author == user.person || object.verify_parent_author_signature
        Rails.logger.info("event=receive status=abort reason='object signature not valid' recipient=#{user.diaspora_handle} sender=#{self.parent.author.diaspora_handle} payload_type=#{self.class} parent_id=#{self.parent.id}")
        return
      end

      #sign object as the parent creator if you've been hit UPSTREAM
      if user.owns? object.parent
        object.parent_author_signature = object.sign_with_key(user.encryption_key)
        object.save!
      end

      #dispatch object DOWNSTREAM, received it via UPSTREAM
      unless user.owns?(object)
        object.save!
        Postzord::Dispatch.new(user, object).post
      end

      object.socket_to_user(user) if object.respond_to? :socket_to_user
      if object.after_receive(user, person)
        object
      end
    end

    def after_receive(user, person)
      self
    end

    def initialize_signatures
      #sign relayable as model creator
      self.author_signature = self.sign_with_key(author.owner.encryption_key)

      if !self.parent.blank? && self.author.owns?(self.parent)
        #sign relayable as parent object owner
        self.parent_author_signature = sign_with_key(author.owner.encryption_key)
      end
    end

    # @return [Boolean]
    def verify_parent_author_signature
      verify_signature(self.parent_author_signature, self.parent.author)
    end

    # @return [Boolean]
    def signature_valid?
      verify_signature(self.author_signature, self.author)
    end

    # @abstract
    # @return [Class]
    def parent_class
      raise NotImplementedError.new('you must override parent_class in order to enable relayable on this model')
    end

    # @abstract
    # @return An instance of Relayable#parent_class
    def parent
      raise NotImplementedError.new('you must override parent in order to enable relayable on this model')
    end

    # @abstract
    # @param parent An instance of Relayable#parent_class
    def parent= parent
      raise NotImplementedError.new('you must override parent= in order to enable relayable on this model')
    end
  end
end