safe-web-socket/v1/client/client.go

package client

import (
	"context"
	"fmt"
	"log"
	"net/url"
	"strings"
	"time"

	custom_rwmutex "git.neurocipta.com/rogerferdinan/custom-rwmutex"
	"git.neurocipta.com/rogerferdinan/safe-web-socket/internal"
	"github.com/gorilla/websocket"
)

const (
	pingPeriod = 10 * time.Second
)

type SafeWebsocketClientBuilder struct {
	baseHost *string `nil_checker:"required"`
	basePort *uint16 `nil_checker:"required"`
	path     *string
	rawQuery *string
	useTLS   *bool
}

func NewSafeWebsocketClientBuilder() *SafeWebsocketClientBuilder {
	return &SafeWebsocketClientBuilder{}
}

func (b *SafeWebsocketClientBuilder) BaseHost(host string) *SafeWebsocketClientBuilder {
	b.baseHost = &host
	return b
}

func (b *SafeWebsocketClientBuilder) BasePort(port uint16) *SafeWebsocketClientBuilder {
	b.basePort = &port
	return b
}

func (b *SafeWebsocketClientBuilder) UseTLS(useTLS bool) *SafeWebsocketClientBuilder {
	b.useTLS = &useTLS
	return b
}

func (b *SafeWebsocketClientBuilder) Path(path string) *SafeWebsocketClientBuilder {
	b.path = &path
	return b
}

func (b *SafeWebsocketClientBuilder) RawQuery(rawQuery string) *SafeWebsocketClientBuilder {
	b.rawQuery = &rawQuery
	return b
}

func (b *SafeWebsocketClientBuilder) Build() (*SafeWebsocketClient, error) {
	if err := internal.NilChecker(b); err != nil {
		return nil, err
	}

	ctx, cancel := context.WithCancel(context.Background())

	var useTLS bool
	if b.useTLS != nil {
		useTLS = *b.useTLS
	}

	wsClient := SafeWebsocketClient{
		baseHost:    *b.baseHost,
		basePort:    *b.basePort,
		useTLS:      useTLS,
		path:        b.path,
		rawQuery:    b.rawQuery,
		ctx:         ctx,
		cancel:      cancel,
		dataChannel: make(chan []byte, 1),
		mu:          custom_rwmutex.NewCustomRwMutex(),
		reconnectCh: make(chan struct{}, 1),
		isConnected: false,
	}

	if err := wsClient.connect(); err != nil {
		cancel()
		return nil, fmt.Errorf("failed to establish initial connection: %v", err)
	}

	return &wsClient, nil
}

type SafeWebsocketClient struct {
	baseHost    string
	basePort    uint16
	useTLS      bool
	path        *string
	rawQuery    *string
	dataChannel chan []byte
	mu          *custom_rwmutex.CustomRwMutex
	conn        *websocket.Conn
	ctx         context.Context
	cancel      context.CancelFunc
	reconnectCh chan struct{}
	isConnected bool
}

func (wsClient *SafeWebsocketClient) connect() error {
	var scheme string
	if wsClient.useTLS {
		scheme = "wss"
	} else {
		scheme = "ws"
	}
	newURL := url.URL{
		Scheme: scheme,
		Host:   fmt.Sprintf("%s:%d", wsClient.baseHost, wsClient.basePort),
	}

	if wsClient.path != nil && strings.TrimSpace(*wsClient.path) != "" {
		newURL.Path = *wsClient.path
	}

	if wsClient.rawQuery != nil && strings.TrimSpace(*wsClient.rawQuery) != "" {
		newURL.RawQuery = *wsClient.rawQuery
	}

	conn, _, err := websocket.DefaultDialer.Dial(newURL.String(), nil)
	if err != nil {
		return fmt.Errorf("failed to connect to %s: %w", wsClient.baseHost, err)
	}

	conn.SetPingHandler(func(pingData string) error {
		if err := conn.WriteMessage(websocket.PongMessage, []byte(pingData)); err != nil {
			if err == websocket.ErrCloseSent {
				return nil
			}
			if netErr, ok := err.(interface{ Timeout() bool }); ok && netErr.Timeout() {
				return nil
			}
			return err
		}
		return nil
	})

	wsClient.mu.WriteHandler(func() error {
		wsClient.conn = conn
		wsClient.isConnected = true
		return nil
	})

	go wsClient.startPingTicker()
	go wsClient.startReceiveHandler()
	go wsClient.reconnectHandler()

	return nil
}

func (wsClient *SafeWebsocketClient) startPingTicker() {
	ticker := time.NewTicker(pingPeriod)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			wsClient.mu.WriteHandler(func() error {
				if err := wsClient.conn.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
					log.Printf("Ping failed: %v. Will attempt reconnect.", err)
					wsClient.triggerReconnect()
				}
				return nil
			})
		case <-wsClient.ctx.Done():
			log.Println("Ping ticker stopped")
			return
		}
	}
}

func (wsClient *SafeWebsocketClient) startReceiveHandler() {
	for {
		select {
		case <-wsClient.reconnectCh:
		case <-wsClient.ctx.Done():
			log.Println("Reconnect handler stopped")
			return
		default:
			if err := wsClient.mu.ReadHandler(func() error {
				conn := wsClient.conn

				if conn == nil {
					return fmt.Errorf("no active connection, waiting for reconnect")
				}
				_, message, err := conn.ReadMessage()
				if err != nil {
					return err
				}
				wsClient.dataChannel <- message
				return nil
			}); err != nil {
				wsClient.triggerReconnect()
				return
			}
		}
	}
}

func (wsClient *SafeWebsocketClient) triggerReconnect() {
	select {
	case wsClient.reconnectCh <- struct{}{}:
	default:
	}
}

func (wsClient *SafeWebsocketClient) reconnectHandler() {
	for range wsClient.reconnectCh {
		wsClient.connect()
	}
}

func (wsClient *SafeWebsocketClient) DataChannel() <-chan []byte {
	return wsClient.dataChannel
}