require 'rack'

module Rack

  module Rewritten

    class Url

      attr_accessor :base_url

      def initialize(app, &block)
        @app = app
        @translate_backwards = false
        @downcase_before_lookup = false
        @translate_partial = false
        @base_url = ''
        instance_eval(&block) if block_given?
      end

      def is_internal_target?(url)
        url.nil? or url.start_with?('/') or url.start_with?(@base_url)
      end

      def is_external_target?(url)
        !is_internal_target?(url)
      end

      def call(env)
        req = Rack::Request.new(env)

        subdomain = env["SUBDOMAIN"] ? "#{env["SUBDOMAIN"]}:" : ""

        path = "#{subdomain}#{req.path_info}"
        path.downcase! if downcase_before_lookup?

        target_url = ::Rewritten.translate(path)

        if is_external_target?(target_url)
          r = Rack::Response.new
          r.redirect(target_url, 301)
          r.finish
        elsif ::Rewritten.includes?(path.chomp("/")) or backwards=( translate_backwards? && ::Rewritten.exist_translation_for?(path) )

          to = ::Rewritten.includes?(path.chomp("/")) || path

          current_path = ::Rewritten.get_current_translation(to)
          current_path = current_path.split(":").last
          current_path = current_path.split('?')[0]

          if (current_path == req.path_info) or (::Rewritten.base_from(req.path_info) == current_path) or ::Rewritten.has_flag?(path, 'L')
            # if this is the current path, rewrite path and parameters
            tpath, tparams = split_to_path_params(to)

            env['QUERY_STRING'] = Rack::Utils.build_query(tparams.merge(req.params))
            req.path_info = tpath + ::Rewritten.appendix(req.path_info)
            @app.call(req.env)
          else
            # if this is not the current path, redirect to current path
            # NOTE: assuming redirection is always to non-subdomain-path

            r = Rack::Response.new

            new_path = env["rack.url_scheme"].dup
            new_path << "://"
            new_path << env["HTTP_HOST"].dup.sub(/^#{subdomain.chomp(':')}\./, '')
            new_path << current_path
            new_path << ::Rewritten.appendix(path) unless backwards
            new_path << '?' << env["QUERY_STRING"] unless (env["QUERY_STRING"]||'').empty?

            r.redirect(new_path, 301)
            a = r.finish
          end
        else
          @app.call(req.env)
        end
      end

      def split_to_path_params(path_and_query)
        path, query_string = path_and_query.split('?').push('')[0..1]
        [path, Rack::Utils.parse_query(query_string)] 
      end

      private

      def translate_backwards?
        @translate_backwards
      end

      def translate_backwards=(yes_or_no)
        @translate_backwards = yes_or_no
      end

      def downcase_before_lookup?
        @downcase_before_lookup
      end

      def downcase_before_lookup=(yes_or_no)
        @downcase_before_lookup = yes_or_no
      end

      def translate_partial?
        @translate_partial
      end

      def translate_partial=(yes_or_no)
        $stderr.puts "DEPRECATED. Please use Rewritten.translate_partial"
        ::Rewritten.translate_partial = yes_or_no
      end
    end
  end
end