+backend base

backend/ssestream.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"io"
+	"log"
+
+	"github.com/gin-gonic/gin"
+)
+
+var events = []string{"message", "timer", "priority"}
+
+type Message struct {
+	Event string `json:"event"`
+	Data  string `json:"data"`
+	Cmd   string `json:"cmd"`
+	Id    string `json:"id"`
+}
+
+type ClientChan chan Message
+
+type Client struct {
+	Id     string     `json:"id"`
+	Ip     string     `json:"ip"`
+	Chan   ClientChan `json:"chan"`
+	Events []string   `json:"events"`
+}
+
+type SseStream struct {
+	Clients []Client `json:"clients"`
+	MsgId   int      `json:"msgid"`
+	Events  []string `json:"events"`
+}
+
+func InitSse() *SseStream {
+	return &SseStream{
+		Clients: make([]Client, 0),
+		MsgId:   0,
+		Events:  events,
+	}
+}
+
+func (sse *SseStream) SseHeadersMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		c.Writer.Header().Set("Content-Type", "text/event-stream")
+		c.Writer.Header().Set("Cache-Control", "no-cache")
+		c.Writer.Header().Set("Connection", "keep-alive")
+		c.Writer.Header().Set("Transfer-Encoding", "chunked")
+		c.Next()
+	}
+}
+
+func (sse *SseStream) Stream(c *gin.Context) {
+	client := &Client{
+		Ip:     c.Request.RemoteAddr,
+		Chan:   make(ClientChan),
+		Events: c.QueryArray("events"),
+	}
+
+	client.Id = generateClientId(client.Ip, client.Events, 8)
+
+	sse.AddClient(*client)
+
+	defer func() {
+		sse.RemoveClient(client)
+		close(client.Chan)
+		log.Printf("Client %s disconnected", client.Ip)
+	}()
+
+	log.Printf("Client %s connected", client.Ip)
+
+	c.Stream(func(w io.Writer) bool {
+		msg, ok := <-client.Chan
+		if !ok {
+			return false
+		}
+		c.SSEvent(msg.Event, msg)
+		return true
+	})
+}
+
+func (sse *SseStream) AddClient(client Client) {
+	sse.Clients = append(sse.Clients, client)
+}
+
+func (sse *SseStream) RemoveClient(client *Client) {
+	for i, c := range sse.Clients {
+		if c.Id == client.Id {
+			sse.Clients = append(sse.Clients[:i], sse.Clients[i+1:]...)
+			return
+		}
+	}
+}