module Yrpc
  module Controllers

    class ServiceBinder
      ##
      #未来可能会有一些desc 的 拓展，先预留一个肉便器类。
      #
      class BoundDesc < SimpleDelegator;
      end

      #初始化。。没什么好解释的
      def initialize(service)
        @service = service
      end


      # 通过controller绑定所有的方法
      def bind!(controller)
        rpc_methods.each { |name, desc| bind_method(controller, name, desc) }
      end

      def rpc_desc(request_method)
        @service.rpc_descs[request_method]
      end

      private


      #打开类并且进行一个方法define，返回给这个方法打call。这里要注意的是request 会以参数形式构造进controller
      #这里也涉及到stream 类型。
      def bind_method(controller, method_name, desc)
        method_desc = method_name.to_s.to_sym
        method_key = method_name.to_s.underscore.to_sym
        current_desc = rpc_desc(method_desc)
        service_ref = @service
        @service.class_eval do
          if desc.request_response?
            define_method(method_key) do |message, active_call|
              c = controller.new(method_key: method_key, service: service_ref, message: message, active_call: active_call, rpc_desc: desc)
              begin
                c.call(method_key)
              rescue => e
                p method_key
                p e.backtrace_locations
                desc && desc.output ? desc.output.new(status: {code: e.respond_to?(:code) ? e.code :  Yrpc::Response::Code::ERROR , message: e.message}) : (raise e)
              end
            end
          elsif desc.client_streamer?
            define_method(method_key) do |active_call|
              c = controller.new(method_key: method_key, service: service_ref, message: proc { |&block| active_call.each_remote_read(&block) }, active_call: active_call, rpc_desc: desc)
              begin
                c.call(method_key)
              rescue => e
                desc && desc.output ? desc.output.new(status: {code: e&.code || Yrpc::Response::Code::ERROR, message: e.message}) : (raise e)
              end
            end
          elsif desc.server_streamer?
            define_method(method_key) do |message, active_call, &block|
              c = controller.new(method_key: method_key, service: service_ref, message: message, active_call: active_call, rpc_desc: desc)
              begin
                c.call(method_key)
              rescue => e
                desc && desc.output ? desc.output.new(status: {code: e&.code || Yrpc::Response::Code::ERROR , message: e.message}) : (raise e)
              end
            end
          else # bidi
            define_method(method_key) do |messages, active_call, &block|
              c = controller.new(method_key: method_key, service: service_ref, message: messages, active_call: active_call, rpc_desc: desc)
              begin
                c.call(method_key)
              rescue => e
                desc && desc.output ? desc.output.new(status: {code: e&.code || Yrpc::Response::Code::ERROR, message: e.message}) : (raise e)
              end
            end
          end
        end
      end

      ##
      # 讲方法都代理到boundDesc 上
      #
      def rpc_methods
        @service.rpc_descs.map { |rd| BoundDesc.new(rd) }
      end
    end
  end
end