module Liars
  class C
    attr_accessor :body, :headers, :status, :params, :cookies

    class << self
      def inherited(child); (@@subclasses ||= []) << child;  end
      def subclasses; @@subclasses; end

      def run(r=$stdin, e=ENV)
        route = e['PATH_INFO']
        @@subclasses.each do |klass|
          action, args = klass.get_action_and_args(route)
          if action
            controller = klass.new(r, e, e['REQUEST_METHOD']||"GET") 
            return controller.send(action, *args) && controller
          end
        end
      end

      def route_of(action, *routes)
        @@routes ||= {}
        @@routes[action] = routes
      end

      # 实际上是返回一个action的名称和这个action所有可能用到的参数列表
      # 如edit上映射的route是'/edit/(\d+)'，而实际访问的路径是'/edit/1'时
      # 1将会被作为一个参数传给edit方法
      def get_action_and_args(route)
        @@routes.each do |action, action_routes|
          action_routes.find do |r| 
            match = Regexp.new("^#{r}$").match(route)
            return action, match[1..-1] if match
          end
        end
      end
    end

    def initialize(r, e, m)
      @status, @method, @env, @headers, @root = 200, m.downcase, e, 
        {'Content-Type'=>'text/html'}, e["SCRIPT_NAME"].sub(/\/$/,'')
      @params = qsp(e["QUERY_STRING"])
      @cookies = kp(e["HTTP_COOKIE"])
      @params.merge!(qsp(r.read)) if @method == "post"
    end

    def redirect_to(url)
      r(302,'','Location'=>url)
    end

    # A quick means of setting this controller's status, body and headers.
    # Used internally by Camping, but... by all means...
    #
    #   r(302, '', 'Location' => self / "/view/12")
    #
    # Is equivalent to:
    #
    #   redirect "/view/12"
    #
    def r(s, b, h = {}); @status = s; @headers.merge!(h); @body = b; end 
    # URL escapes a string.
    #
    #   Camping.escape("I'd go to the museum straightway!")  
    #     #=> "I%27d+go+to+the+museum+straightway%21"
    #
    def escape(s); s.to_s.gsub(/[^ \w.-]+/n){'%'+($&.unpack('H2'*$&.size)*'%').upcase}.tr(' ', '+') end

    # Unescapes a URL-encoded string.
    #
    #   Camping.un("I%27d+go+to+the+museum+straightway%21") 
    #     #=> "I'd go to the museum straightway!"
    #
    def un(s); s.tr('+', ' ').gsub(/%([\da-f]{2})/in){[$1].pack('H*')} end

    def qsp(qs, d='&;')
      (qs || '').split(/[#{d}] */n).inject({}) do |h, p|
        k, v = un(p).split('=', 2)
        if (k = k.split(/[\]\[]+/)).length == 1
          h[k[0].to_sym] = v
        else
          (h[k[0].to_sym] ||= {})[k[1].to_sym] = v
        end
        h
      end
    end

    def kp(s); qsp(s, ';,'); end 

    def render(action=(caller[0]=~/`(\w+)'/;$1))
      # 查找当前controller对应的view，然后根据action来找到渲染方法
      name = (self.class.to_s =~ /(\w+)(C|Controller)$/; $1)
      view_class = eval("#{name}View") rescue eval("#{name}V")
      view_instance = view_class.new
      instance_variables.each do |iv|
        view_instance.instance_variable_set(iv, instance_variable_get(iv))
      end
      render_result = view_instance.respond_to?(:layout) ?
        view_instance.send(:layout, &view_instance.method(action)) :
        view_instance.send(action)
      @body = view_instance.stream || render_result
    end
  end
end