require 'active_support/concern'

module Relatable
  extend ActiveSupport::Concern

  included do
    has_many :active_relationships,  class_name:  "Relationship",
                                    #foreign_key: "follower_id",
                                    as: :source,
                                    dependent: :destroy
    has_many :passive_relationships, class_name:  "Relationship",
                                    #foreign_key: "followed_id",
                                    as: :destination,
                                    dependent: :destroy

    #has_many :followers, through: :passive_relationships, source: :source, source_type: User

  end

  class_methods do

  end


  def relate!(name, destination)
    active_relationships.create!(name: name, destination: destination)
  end


  def unrelate!(name, destination)
    relation = active_relationships.find_by(name: name, destination_id: destination.id)
    relation.destroy if relation
  end


  def relatives_from(name, klass=nil)
    objects = passive_relationships.where(name: name).map{|ar| ar.destination}
    objects.reject!{|o| o.class != klass} if klass
    objects
  end

  def relatives_to(name, klass=nil)
    objects = active_relationships.where(name: name).map{|ar| ar.destination}
    objects.reject!{|o| o.class != klass} if klass
    objects
  end

  def owner
    self.is_a?(User) ? self : self.user
  end

  #FOLLOW

  def followers(klass=nil)
    relatives_from(Relationship::RELATION_FOLLOW)
  end


  def followings(klass=nil)
    relatives_to(Relationship::RELATION_FOLLOW)
  end


  def follow(destination)
    relate!(Relationship::RELATION_FOLLOW, destination)
  end


  def unfollow(destination)
    unrelate!(Relationship::RELATION_FOLLOW, destination)
  end


  def is_following?(other_user)
    self.followings.index(other_user)
  end


  def relate_name
    return self.name if self.respond_to? :name
    return self.title if self.respond_to? :title
    "#{self.class.name} #{self.id}"
  end




end