feat: initialise project structure with core encoding queue, database models, and web management API

internal/web/sse.go

@@ -0,0 +1,75 @@
+package web
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sync"
+	"time"
+)
+
+type SSEMessage struct {
+	Event string
+	Data  interface{}
+}
+
+type SSEServer struct {
+	clients map[chan SSEMessage]bool
+	mu      sync.Mutex
+}
+
+func NewSSEServer() *SSEServer {
+	return &SSEServer{
+		clients: make(map[chan SSEMessage]bool),
+	}
+}
+
+func (s *SSEServer) HandleSSE(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Connection", "keep-alive")
+
+	clientChan := make(chan SSEMessage)
+	s.mu.Lock()
+	s.clients[clientChan] = true
+	s.mu.Unlock()
+
+	defer func() {
+		s.mu.Lock()
+		delete(s.clients, clientChan)
+		s.mu.Unlock()
+		close(clientChan)
+	}()
+
+	notify := r.Context().Done()
+
+	for {
+		select {
+		case <-notify:
+			return
+		case msg := <-clientChan:
+			dataBytes, err := json.Marshal(msg.Data)
+			if err != nil {
+				continue
+			}
+			fmt.Fprintf(w, "event: %s\ndata: %s\n\n", msg.Event, string(dataBytes))
+			w.(http.Flusher).Flush()
+		case <-time.After(30 * time.Second):
+			// Keepalive
+			fmt.Fprintf(w, "event: ping\ndata: {}\n\n")
+			w.(http.Flusher).Flush()
+		}
+	}
+}
+
+func (s *SSEServer) Broadcast(event string, data interface{}) {
+	msg := SSEMessage{Event: event, Data: data}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for clientChan := range s.clients {
+		select {
+		case clientChan <- msg:
+		default:
+		}
+	}
+}