Just a POC

Author: thani-sh

main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"./server"
+	"fmt"
+	"net/http"
+)
+
+func main() {
+	server := server.New()
+
+	server.Method("hello", func(p []interface{}) (interface{}, error) {
+		return "result", nil
+	})
+
+	http.HandleFunc("/websocket", server.Handler)
+	http.ListenAndServe(":9000", nil)
+}

server/server.go

@@ -0,0 +1,223 @@
+package server
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"math/rand"
+	"net/http"
+
+	"github.com/gorilla/websocket"
+)
+
+type MethodHandler func([]interface{}) (interface{}, error)
+
+type Server struct {
+	ws      *websocket.Conn
+	methods map[string]MethodHandler
+}
+
+type Message struct {
+	Msg     string        `json:"msg"`
+	Session string        `json:"session"`
+	Version string        `json:"version"`
+	Support []string      `json:"support"`
+	Id      string        `json:"id"`
+	Method  string        `json:"method"`
+	Params  []interface{} `json:"params"`
+	Result  string        `json:"result"`
+	Methods []string      `json:"methods"`
+}
+
+// type ConnectMessage struct {
+// 	Msg     string   `json:"msg"`
+// 	Session string   `json:"session"`
+// 	Version string   `json:"version"`
+// 	Support []string `json:"support"`
+// }
+
+// type ConnectedMessage struct {
+// 	Msg     string `json:"msg"`
+// 	Session string `json:"session"`
+// }
+
+// type PingWithIdMessage struct {
+// 	Msg string `json:"msg"`
+// 	Id  string `json:"id"`
+// }
+
+// type PingWithoutIdMessage struct {
+// 	Msg string `json:"msg"`
+// }
+
+// type PongWithIdMessage struct {
+// 	Msg string `json:"msg"`
+// 	Id  string `json:"id"`
+// }
+
+// type PongWithoutIdMessage struct {
+// 	Msg string `json:"msg"`
+// }
+
+// type MethodMessage struct {
+// 	Msg    string        `json:"msg"`
+// 	Id     string        `json:"id"`
+// 	Method string        `json:"method"`
+// 	Params []interface{} `json:"params"`
+// }
+
+// type ResultWithErrorMessage struct {
+// 	Msg   string `json:"msg"`
+// 	Id    string `json:"id"`
+// 	Error Error  `json:"error"`
+// }
+
+// type ResultWithoutErrorMessage struct {
+// 	Msg    string `json:"msg"`
+// 	Id     string `json:"id"`
+// 	Result string `json:"result"`
+// }
+
+// type UpdatedMessage struct {
+// 	Msg     string   `json:"msg"`
+// 	Methods []string `json:"methods"`
+// }
+
+// type Error struct {
+// 	error   string
+// 	reason  string
+// 	details string
+// }
+
+var upgrader = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+}
+
+func New() Server {
+	server := Server{}
+	server.methods = make(map[string]MethodHandler)
+	return server
+}
+
+func (s *Server) Method(n string, h MethodHandler) {
+	s.methods[n] = h
+}
+
+// create websocket connection from http handler and runs the websocket handler
+func (s *Server) Handler(w http.ResponseWriter, r *http.Request) {
+	ws, err := upgrader.Upgrade(w, r, nil)
+	s.ws = ws
+
+	if err != nil {
+		fmt.Println("Error: could not creating websocket connection")
+		return
+	}
+
+	for {
+		msg, err := readMessage(ws)
+
+		if err != nil {
+			fmt.Println("Error: could not read from websocket connection")
+			ws.Close()
+			break
+		}
+
+		fmt.Println("Message =>", msg)
+
+		switch {
+		case msg.Msg == "ping":
+			go s.HandlePing(ws, &msg)
+		case msg.Msg == "connect":
+			go s.HandleConnect(ws, &msg)
+		case msg.Msg == "method":
+			go s.HandleMethod(ws, &msg)
+		default:
+			fmt.Println("Error: unknown ddp message", msg)
+		}
+	}
+}
+
+func (s *Server) HandleConnect(c *websocket.Conn, m *Message) {
+	err := c.WriteJSON(map[string]string{
+		"msg":     "connected",
+		"session": randId(17),
+	})
+
+	if err != nil {
+		fmt.Println(err)
+	}
+}
+
+func (s *Server) HandlePing(c *websocket.Conn, m *Message) {
+	if m.Id != "" {
+		err := c.WriteJSON(map[string]string{
+			"msg": "pong",
+			"id":  m.Id,
+		})
+
+		if err != nil {
+			fmt.Println(err)
+		}
+	} else {
+		err := c.WriteJSON(map[string]string{
+			"msg": "pong",
+		})
+
+		if err != nil {
+			fmt.Println(err)
+		}
+	}
+}
+
+func (s *Server) HandleMethod(c *websocket.Conn, m *Message) {
+	res, _ := s.methods[m.Method](m.Params)
+	err := c.WriteJSON(map[string]interface{}{
+		"msg":    "result",
+		"id":     m.Id,
+		"result": res,
+	})
+
+	if err != nil {
+		fmt.Println(err)
+	}
+
+	err = c.WriteJSON(map[string]interface{}{
+		"msg":     "updated",
+		"methods": []string{m.Id},
+	})
+
+	if err != nil {
+		fmt.Println(err)
+	}
+}
+
+func readMessage(ws *websocket.Conn) (Message, error) {
+	t, str, err := ws.ReadMessage()
+	msg := Message{}
+
+	if err != nil {
+		// error reading message
+		return msg, err
+	}
+
+	if t != 1 {
+		// ignore binary data
+		err = errors.New("Error: websocket data is binary")
+		return msg, err
+	}
+
+	err = json.Unmarshal(str, &msg)
+	return msg, err
+}
+
+// TODO: move this to another package
+var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+func randId(n int) string {
+	b := make([]rune, n)
+	for i := range b {
+		b[i] = letters[rand.Intn(len(letters))]
+	}
+	return string(b)
+}