module Spec
  module Matchers

    def self.create(name, &block)
      @guid ||= 0
      mod = Module.new do
        klass = Class.new(MatcherDSL) do
          def initialize(expected_value)
            @expected_value = expected_value
          end
        end
        klass.class_eval(&block)

        define_method(name) do |*expected_value|
          # Avoid a warning for the form should foo.
          klass.new(expected_value && expected_value[0])
        end
      end
      Merb::Test::ExampleGroup.send(:include, mod)
    end

    class MatcherDSL
      include Merb::Test::RouteHelper

      def self.matches(&block)
        define_method(:matches_proxy, &block)

        define_method(:matches?) do |object|
          @object = object
          if block.arity == 2
            matches_proxy(@object, @expected_value)
          else
            matches_proxy(@object)
          end
        end
      end

      def self.expected_value(&block)
        define_method(:transform_expected, &block)

        define_method(:initialize) do |expected_value|
          @expected_value = transform_expected(expected_value) || expected_value
        end
      end

      def self.negative_failure_message(&block)
        define_method(:proxy_negative_failure_message, &block)

        define_method(:negative_failure_message) do
          proxy_negative_failure_message(@object, @expected_value)
        end
      end

      def self.failure_message(&block)
        define_method(:proxy_failure_message, &block)

        define_method(:failure_message) do
          proxy_failure_message(@object, @expected_value)
        end
      end

      def self.message(&block)
        class_eval do
          def failure_message
            generic_message(@object, @expected_value, nil)
          end

          def negative_failure_message
            generic_message(@object, @expected_value, " not")
          end
        end

        define_method(:proxy_generic_message, &block)

        define_method(:generic_message) do |object, expected, not_string|
          proxy_generic_message(not_string, object, expected)
        end
      end
    end

  end
end