module CassandraObject
  module Associations
    class OneToMany
      def initialize(association_name, owner_class, options)
        @association_name  = association_name.to_s
        @owner_class       = owner_class
        @target_class_name = options[:class_name] || association_name.to_s.singularize.camelize
        @options           = options

        define_methods!
      end

      def find(owner, options = {})
        reversed = options.has_key?(:reversed) ? options[:reversed] : reversed?
        cursor   = CassandraObject::Cursor.new(target_class, column_family, owner.key.to_s, @association_name, :start_after => options[:start_after], :reversed => reversed)
        cursor.find(options[:limit] || 100)
      end

      def add(owner, record, set_inverse = true)
        key = owner.key
        attributes = {@association_name=>{new_key=>record.key.to_s}}
        ActiveSupport::Notifications.instrument("insert.cassandra_object", :column_family => column_family, :key => key, :attributes => attributes) do
          connection.insert(column_family, key.to_s, attributes, :consistency => @owner_class.thrift_write_consistency)
        end
        if has_inverse? && set_inverse
          inverse.set_inverse(record, owner)
        end
      end

      def new_key
        SimpleUUID::UUID.new
      end

      def column_family
        @owner_class.relationships_column_family
      end

      def connection
        @owner_class.connection
      end

      def target_class
        @target_class ||= @target_class_name.constantize
      end

      def new_proxy(owner)
        OneToManyAssociationProxy.new(self, owner)
      end

      def has_inverse?
        @options[:inverse_of]
      end

      def inverse
        has_inverse? && target_class.associations[@options[:inverse_of]]
      end

      def set_inverse(owner, record)
        add(owner, record, false)
      end

      def reversed?
        @options[:reversed] == true
      end

      def define_methods!
        @owner_class.class_eval <<-eos
        def #{@association_name}
          @_#{@association_name} ||= self.class.associations[:#{@association_name}].new_proxy(self)
        end
        eos
      end
    end

    class OneToManyAssociationProxy
      def initialize(association, owner)
        @association = association
        @owner       = owner
      end

      include Enumerable
      def each
        target.each do |i|
          yield i
        end
      end

      def [](index)
        to_a[index]
      end

      def <<(record)
        @association.add(@owner, record)
        if loaded?
          @target << record
        end
      end

      # Get the targets of this association proxy
      #
      # @param  [Hash] options the options with which to modify this query
      # @option options [String]  :start_after the key after which to start returning results
      # @option options [Boolean] :reversed (false or association default) return the results in reverse order
      # @option options [Integer] :limit the max number of results to return
      # @return [Array<CassandraObject::Base>] an array of objects of type self#target_class
      #
      def all(options = {})
        @association.find(@owner, options)
      end

      # Create a record of the associated type with 
      # the supplied attributes and add it to this 
      # association
      #
      # @param  [Hash] attributes the attributes with which to create the object
      # @return [CassandraObject::Base] the newly created object
      #
      def create(attributes)
        @association.target_class.create(attributes).tap do |record|
          if record.valid?
            self << record
          end
        end
      end

      def create!(attributes)
        @association.target_class.create!(attributes).tap do |record|
          self << record
        end
      end

      def target
        @target ||= begin
                      @loaded = true
                      @association.find(@owner)
                    end
      end

      alias to_a target

      def loaded?
        defined?(@loaded) && @loaded
      end
    end
  end
end