initial vibes

backend/hub.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"context"
+	"sync"
+
+	"github.com/coder/websocket"
+)
+
+type hub struct {
+	mu    sync.Mutex
+	conns map[string]map[*websocket.Conn]struct{}
+}
+
+func newHub() *hub {
+	return &hub{conns: make(map[string]map[*websocket.Conn]struct{})}
+}
+
+func (h *hub) add(listID string, c *websocket.Conn) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if h.conns[listID] == nil {
+		h.conns[listID] = make(map[*websocket.Conn]struct{})
+	}
+	h.conns[listID][c] = struct{}{}
+}
+
+func (h *hub) remove(listID string, c *websocket.Conn) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	delete(h.conns[listID], c)
+	if len(h.conns[listID]) == 0 {
+		delete(h.conns, listID)
+	}
+}
+
+func (h *hub) broadcast(listID string) {
+	h.mu.Lock()
+	conns := make([]*websocket.Conn, 0, len(h.conns[listID]))
+	for c := range h.conns[listID] {
+		conns = append(conns, c)
+	}
+	h.mu.Unlock()
+
+	for _, c := range conns {
+		go c.Write(context.Background(), websocket.MessageText, []byte("changed"))
+	}
+}