Add basic web app and API integration

ws.go

@@ -0,0 +1,130 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+	"strconv"
+	"sync"
+
+	"github.com/gorilla/websocket"
+)
+
+var upgrader = websocket.Upgrader{
+	CheckOrigin: func(r *http.Request) bool { return true },
+}
+
+type wsMessage struct {
+	Type    string `json:"type"`
+	Payload any    `json:"payload,omitempty"`
+}
+
+type client struct {
+	conn          *websocket.Conn
+	competitionID int64
+	send          chan []byte
+}
+
+type Hub struct {
+	mu      sync.RWMutex
+	clients map[int64]map[*client]struct{}
+}
+
+var hub *Hub
+
+func newHub() *Hub {
+	return &Hub{clients: map[int64]map[*client]struct{}{}}
+}
+
+func (h *Hub) run() {}
+
+func (h *Hub) register(c *client) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	set, ok := h.clients[c.competitionID]
+	if !ok {
+		set = map[*client]struct{}{}
+		h.clients[c.competitionID] = set
+	}
+	set[c] = struct{}{}
+}
+
+func (h *Hub) unregister(c *client) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if set, ok := h.clients[c.competitionID]; ok {
+		if _, ok := set[c]; ok {
+			delete(set, c)
+			close(c.send)
+		}
+		if len(set) == 0 {
+			delete(h.clients, c.competitionID)
+		}
+	}
+}
+
+func (h *Hub) broadcast(competitionID int64, kind string, payload any) {
+	msg := wsMessage{Type: kind, Payload: payload}
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return
+	}
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	set, ok := h.clients[competitionID]
+	if !ok {
+		return
+	}
+	for c := range set {
+		select {
+		case c.send <- data:
+		default:
+		}
+	}
+}
+
+func registerWSRoutes(mux *http.ServeMux) {
+	mux.HandleFunc("GET /api/competitions/{id}/ws", requireAuth(handleWS))
+}
+
+func handleWS(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid_id")
+		return
+	}
+	u := userFromCtx(r)
+	if _, ok := canAccessCompetition(u, id); !ok {
+		writeError(w, http.StatusForbidden, "forbidden")
+		return
+	}
+	conn, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		return
+	}
+	c := &client{conn: conn, competitionID: id, send: make(chan []byte, 16)}
+	hub.register(c)
+	go writePump(c)
+	readPump(c)
+}
+
+func readPump(c *client) {
+	defer func() {
+		hub.unregister(c)
+		c.conn.Close()
+	}()
+	c.conn.SetReadLimit(1024)
+	for {
+		if _, _, err := c.conn.ReadMessage(); err != nil {
+			return
+		}
+	}
+}
+
+func writePump(c *client) {
+	defer c.conn.Close()
+	for msg := range c.send {
+		if err := c.conn.WriteMessage(websocket.TextMessage, msg); err != nil {
+			return
+		}
+	}
+}