HomesteadGateway/ws/websocket.go

package ws

import (
	"context"
	"encoding/json"
	"fmt"
	"homestead/homestead_gateway/util/config"
	"log/slog"
	"net"
	"net/http"
	"os/signal"
	"syscall"
	"time"

	"github.com/gorilla/websocket"
)

func NewWebsocketGateway(cfg config.GatewayConfig, logger *slog.Logger, closefn func() error) *WebsocketGateway {
	return &WebsocketGateway{
		logger:        logger,
		closeFn:       closefn,
		port:          cfg.HttpPort,
		apiKey:        cfg.Websocket,
		upgrader:      NewUpgrader(),
		registry:      NewRegistry(cfg.QueueSize),
		bodySizeBytes: int64(cfg.BodySize) * 1024 * 1024,
	}
}

func (wsg *WebsocketGateway) Start() error {
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	return wsg.Serve(ctx, fmt.Sprintf(":%d", wsg.port))
}

func (wsg *WebsocketGateway) Serve(ctx context.Context, listenAddr string) error {
	mux := http.NewServeMux()
	mux.HandleFunc("/sync", wsg.handleSync)
	mux.HandleFunc("/health", wsg.handleHealth)

	srv := &http.Server{
		Addr:        listenAddr,
		Handler:     wsg.loggingMiddleware(mux),
		BaseContext: func(l net.Listener) context.Context { return ctx },
	}
	errCh := make(chan error, 1)

	go wsg.listen(srv, listenAddr, errCh)

	select {
	case <-ctx.Done():
		wsg.deafen(srv)
		return nil
	case err := <-errCh:
		return err
	}
}

//

func (wsg *WebsocketGateway) read(conn *websocket.Conn, _type, channelId string) {
	defer func() {
		wsg.unregisterConn(_type, channelId)
		wsg.logger.Info("Client disconnected.", "remote", conn.RemoteAddr().String())
	}()

	ticker := time.NewTicker(30 * time.Second)
	ctx, cancel := context.WithCancel(context.Background())
	defer ticker.Stop()
	defer cancel()

	go func() {
		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				wsg.sendWebsocketPing(conn)
			}
		}
	}()

	for {
		typ, data, err := conn.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseNormalClosure) {
				wsg.logger.Error("Client unexpectedly closed the connection.", "err", err)
			}
			return
		}

		if typ != websocket.TextMessage && typ != websocket.BinaryMessage {
			continue
		}

		ts := time.Now().UTC()
		var message GatewayMessageIn
		if err := json.Unmarshal(data, &message); err != nil {
			wsg.sendWebsocketError(conn, "Malformed message.", 400, false)
			wsg.logger.Warn("Received malformed message json from client.", "remote", conn.RemoteAddr().String(), "err", err)
			continue
		}

		message.Type = _type
		message.ReceivedAt = ts
		if err := message.Validate(); err != nil {
			wsg.sendWebsocketError(conn, "Malformed message.", 400, false)
			wsg.logger.Warn("Received malformed message json from client; validation failed.", "remote", conn.RemoteAddr().String(), "err", err)
			continue
		}

		var outID string
		if _type == "mod" {
			outID = channelId
		} else {
			outID = message.ID
		}

		out := GatewayMessageOut{
			Type:        message.Type,
			ID:          outID,
			Author:      message.Author,
			Content:     message.Content,
			Meta:        message.Meta,
			Ts:          message.Ts,
			ReceivedAt:  message.ReceivedAt,
			ForwardedAt: time.Now().UTC(),
		}

		delivered, queued, err := wsg.registry.Send(out.ID, out, func(c *websocket.Conn, m GatewayMessageOut) error {
			_ = c.SetWriteDeadline(time.Now().Add(5 * time.Second))
			return c.WriteJSON(m)
		})

		if err != nil {
			wsg.logger.Error("registry send error", "err", err)
			_ = wsg.sendWebsocketResponse(conn, GatewayAck{Status: "failed", Type: message.Type})
			continue
		}

		if delivered {
			_ = wsg.sendWebsocketResponse(conn, GatewayAck{Status: "completed", Type: message.Type})
			continue
		}

		if queued {
			_ = wsg.sendWebsocketResponse(conn, GatewayAck{Status: "queued", Type: message.Type})
			continue
		}

		_ = wsg.sendWebsocketResponse(conn, GatewayAck{Status: "failed", Type: message.Type})

	}
}