roadamp/internal/server/hub.go

//go:build windows

package server

import (
	"log"
	"time"

	"github.com/gorilla/websocket"
)

const (
	writeWait      = 10 * time.Second
	pongWait       = 60 * time.Second
	pingPeriod     = pongWait * 9 / 10
	maxMessageSize = 512
)

// hub maintains the set of active WebSocket clients and broadcasts messages.
type hub struct {
	clients    map[*wsClient]struct{}
	broadcast  chan []byte
	register   chan *wsClient
	unregister chan *wsClient
	onCmd      func([]byte) // called for each message from any client
}

func newHub(onCmd func([]byte)) *hub {
	return &hub{
		clients:    make(map[*wsClient]struct{}),
		broadcast:  make(chan []byte, 64),
		register:   make(chan *wsClient, 8),
		unregister: make(chan *wsClient, 8),
		onCmd:      onCmd,
	}
}

func (h *hub) run() {
	for {
		select {
		case c := <-h.register:
			h.clients[c] = struct{}{}
		case c := <-h.unregister:
			if _, ok := h.clients[c]; ok {
				delete(h.clients, c)
				close(c.send)
			}
		case msg := <-h.broadcast:
			for c := range h.clients {
				select {
				case c.send <- msg:
				default:
					// Slow client — drop and disconnect.
					close(c.send)
					delete(h.clients, c)
				}
			}
		}
	}
}

// ── wsClient ──────────────────────────────────────────────────────────────────

type wsClient struct {
	hub  *hub
	conn *websocket.Conn
	send chan []byte
}

func (c *wsClient) readPump() {
	defer func() {
		c.hub.unregister <- c
		c.conn.Close()
	}()
	c.conn.SetReadLimit(maxMessageSize)
	c.conn.SetReadDeadline(time.Now().Add(pongWait))
	c.conn.SetPongHandler(func(string) error {
		c.conn.SetReadDeadline(time.Now().Add(pongWait))
		return nil
	})
	for {
		_, msg, err := c.conn.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err,
				websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
				log.Printf("ws read: %v", err)
			}
			break
		}
		if c.hub.onCmd != nil {
			c.hub.onCmd(msg)
		}
	}
}

func (c *wsClient) writePump() {
	ticker := time.NewTicker(pingPeriod)
	defer func() {
		ticker.Stop()
		c.conn.Close()
	}()
	for {
		select {
		case msg, ok := <-c.send:
			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
			if !ok {
				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
				return
			}
			if err := c.conn.WriteMessage(websocket.TextMessage, msg); err != nil {
				return
			}
		case <-ticker.C:
			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
				return
			}
		}
	}
}