package server

import (
	"fmt"
	"log"
	"net"
)

// Server: transport底層實(shí)現(xiàn)，通過(guò)Server去接受客戶端的字節(jié)流
type Server struct {
	ls   net.Listener
	port int
}

// NewServer: 根據(jù)端口創(chuàng)建一個(gè)server
func NewServer(port int) *Server {
	s := &Server{port: port}
	s.init()
	return s
}

// init: 初始化服務(wù)端連接
func (s *Server) init() {
	l, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", s.port))
	if err != nil {
		panic(err)
	}
	s.ls = l
}

// Start: 啟動(dòng)服務(wù)端的端口監(jiān)聽，采取一個(gè)conn一個(gè)g的模型，沒(méi)有使用reactor等高性能模型
func (s *Server) Start() {
	go func() {
		log.Printf("server [%s] start....", s.ls.Addr().String())
		for {
			conn, err := s.ls.Accept()
			if err != nil {
				panic(err)
			}
			go func() {
				buf := make([]byte, 1024)
				for {
					idx, err := conn.Read(buf)
					if err != nil {
						panic(err)
					}
					if len(buf) == 0 {
						continue
					}
					// todo 等序列化的信息
					log.Printf("[conn: %v] get data: %v\n", conn.RemoteAddr(), string(buf[:idx]))

				}
			}()
		}
	}()

}

// Close: 關(guān)閉服務(wù)監(jiān)聽
func (s *Server) Close() error {
	return s.ls.Close()
}


// Close: 關(guān)閉服務(wù)監(jiān)聽
func (s *Server) Close() error {
	return s.ls.Close()
}

package client

import (
	"fmt"
	"log"
	"net"
	"unsafe"
)

type Client struct {
	port int
	conn net.Conn
}

func NewClient(port int) *Client {
	c := &Client{port: port}
	c.init()
	return c
}

// init: initialize tcp client
func (c *Client) init() {
	conn, err := net.Dial("tcp", fmt.Sprintf("127.0.0.1:%d", c.port))
	if err != nil {
		panic(err)
	}
	c.conn = conn

}

func (c *Client) Send(statement string) error {
	_, err := c.conn.Write(*(*[]byte)(unsafe.Pointer(&statement)))
	if err != nil {
		panic(err)
	}
	return nil
}

// Close: use to close connection
func (c *Client) Close() error {
	return c.conn.Close()
}

package main

import (
	"rpc_demo/internal/client"
	"rpc_demo/internal/server"
	"time"
)

func main() {
	s := server.NewServer(9999)
	s.Start()
	time.Sleep(5 * time.Second)
	c := client.NewClient(9999)
	c.Send("this is a test\n")
	time.Sleep(5 * time.Second)
}

package internal

import (
	"errors"
	"fmt"
	"reflect"
	"runtime"
	"strings"
)

// 全局唯一
var GlobalMethod = &Method{methods: map[string]reflect.Value{}}

type Method struct {
	methods map[string]reflect.Value
}

func (m *Method) register(impl interface{}) error {
	pl := reflect.ValueOf(impl)
	if pl.Kind() != reflect.Func {
		return errors.New("impl should be function")
	}
	// 獲取函數(shù)名
	methodName := runtime.FuncForPC(pl.Pointer()).Name()
	if len(strings.Split(methodName, ".")) < 1 {
		return errors.New("invalid function name")
	}
	lastFuncName := strings.Split(methodName, ".")[1]
	m.methods[lastFuncName] = pl
	fmt.Printf("methods: %v\n", m.methods)
	return nil
}

func (m *Method) call(methodName string, callParams ...interface{}) ([]interface{}, error) {
	fn, ok := m.methods[methodName]
	if !ok {
		return nil, errors.New("impl method not found! Please Register first")
	}
	in := make([]reflect.Value, len(callParams))
	for i := 0; i < len(callParams); i++ {
		in[i] = reflect.ValueOf(callParams[i])
	}
	res := fn.Call(in)
	out := make([]interface{}, len(res))
	for i := 0; i < len(res); i++ {
		out[i] = res[i].Interface()
	}
	return out, nil
}

func Call(methodName string, callParams ...interface{}) ([]interface{}, error) {
	return GlobalMethod.call(methodName, callParams...)
}

func Register(impl interface{}) error {
	return GlobalMethod.register(impl)
}

package internal

import (
	"testing"
)

func Sum(a, b int) int {
	return a + b
}
func TestRegister(t *testing.T) {
	err := Register(Sum)
	if err != nil {
		t.Fatalf("err: %v\n", err)
	}
	t.Logf("test success\n")
}

func TestCall(t *testing.T) {
	TestRegister(t)
	result, err := Call("Sum", 1, 2)
	if err != nil {
		t.Fatalf("err: %v\n", err)
	}
	if len(result) != 1 {
		t.Fatalf("len(result) is not equal to 1\n")
	}
	t.Logf("Sum(1,2) = %d\n", result[0].(int))
	if err := recover(); err != nil {
		t.Fatalf("%v\n", err)
	}
}

type RpcRequest struct {
	MethodName string
	Params     []interface{}
}

type RpcResponses struct {
	Returns []interface{}
	Err     error
}

package transport

// Transport: 序列化格式的抽象層，從connection中讀取數(shù)據(jù)序列化并且反序列化到connection中
type Transport interface {
	Decode(v interface{}) error
	Encode(v interface{}) error
	Close()
}

package transport

import (
	"encoding/json"
	"net"
)

var _ Transport = (*JSONTransport)(nil)

type JSONTransport struct {
	encoder *json.Encoder
	decoder *json.Decoder
}

// NewJSONTransport: 負(fù)責(zé)讀取和寫入conn
func NewJSONTransport(conn net.Conn) *JSONTransport {
	return &JSONTransport{json.NewEncoder(conn), json.NewDecoder(conn)}
}

// Decode: use json package to decode
func (t *JSONTransport) Decode(v interface{}) error {
	if err := t.decoder.Decode(v); err != nil {
		return err
	}
	return nil
}

// Encode: use json package to encode
func (t *JSONTransport) Encode(v interface{}) error {
	if err := t.encoder.Encode(v); err != nil {
		return err
	}
	return nil
}

// Close: not implement
func (dec *JSONTransport) Close() {

}

//...
		for {
			conn, err := s.ls.Accept()
			if err != nil {
				panic(err)
			}
			tsp := transport.NewJSONTransport(conn)
			go func() {
				for {
					request := &internal.RpcRequest{}
					err := tsp.Decode(request)
					if err != nil {
						panic(err)
					}
					log.Printf("[server] get request: %v\n", request)
					result, err := internal.Call(request.MethodName, request.Params...)
					log.Printf("[server] invoke method: %v\n", result)
					if err != nil {
						response := &internal.RpcResponses{Returns: nil, Err: err}
						tsp.Encode(response)
						continue
					}
					response := &internal.RpcResponses{Returns: result, Err: err}
					if err := tsp.Encode(response); err != nil {
						log.Printf("[server] encode response err: %v\n", err)
						continue
					}
				}
			}()
		}
        //...

// ...
// Call: remote invoke
func (c *Client) Call(methodName string, params ...interface{}) (res *internal.RpcResponses) {
	request := internal.RpcRequest{MethodName: methodName, Params: params}
	log.Printf("[client] create request to invoke server: %v\n", request)
	err := c.tsp.Encode(request)
	if err != nil {
		panic(err)
	}
	res = &internal.RpcResponses{}
	if err := c.tsp.Decode(res); err != nil {
		panic(err)
	}
	log.Printf("[client] get response from server: %v\n", res)
	return res
}
// ...

package main

import (
	"log"
	"rpc_demo/internal"
	"rpc_demo/internal/client"
	"rpc_demo/internal/server"
	"strings"
	"time"
)

// Rpc方法的一個(gè)簡(jiǎn)易實(shí)現(xiàn)
func Join(a ...string) string {
	res := &strings.Builder{}
	for i := 0; i < len(a); i++ {
		res.WriteString(a[i])
	}
	return res.String()
}

func main() {
	internal.Register(Join)
	s := server.NewServer(9999)
	s.Start()
	time.Sleep(5 * time.Second)
	c := client.NewClient(9999)
	res := c.Call("Join", "aaaaa", "bbbbb", "ccccccccc", "end")
	if res.Err != nil {
		log.Printf("[main] get an error from server: %v\n", res.Err)
		return
	}
	log.Printf("[main] get a response from server: %v\n", res.Returns[0].(string))
	time.Sleep(5 * time.Second)
}