package bybit_connector

import (
	"context"
	"crypto/hmac"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"time"

	"github.com/google/uuid"
	"github.com/gorilla/websocket"
)

type MessageHandler func(message string) error

func (b *WebSocket) handleIncomingMessages() {
	for {
		_, message, err := b.conn.ReadMessage()
		if err != nil {
			fmt.Println("Error reading:", err)
			return
		}

		if b.onMessage != nil {
			err := b.onMessage(string(message))
			if err != nil {
				fmt.Println("Error handling message:", err)
				return
			}
		}
	}
}

func (b *WebSocket) SetMessageHandler(handler MessageHandler) {
	b.onMessage = handler
}

type WebSocket struct {
	conn         *websocket.Conn
	url          string
	apiKey       string
	apiSecret    string
	maxAliveTime string
	pingInterval int
	onMessage    MessageHandler
	ctx          context.Context
	cancel       context.CancelFunc
}

type WebsocketOption func(*WebSocket)

func WithPingInterval(pingInterval int) WebsocketOption {
	return func(c *WebSocket) {
		c.pingInterval = pingInterval
	}
}

func WithMaxAliveTime(maxAliveTime string) WebsocketOption {
	return func(c *WebSocket) {
		c.maxAliveTime = maxAliveTime
	}
}

func NewBybitPrivateWebSocket(url, apiKey, apiSecret string, handler MessageHandler, options ...WebsocketOption) *WebSocket {
	c := &WebSocket{
		url:          url,
		apiKey:       apiKey,
		apiSecret:    apiSecret,
		maxAliveTime: "",
		pingInterval: 20,
		onMessage:    handler,
	}

	// Apply the provided options
	for _, opt := range options {
		opt(c)
	}

	return c
}

func NewBybitPublicWebSocket(url string, pingInterval int, handler MessageHandler, options ...WebsocketOption) *WebSocket {
	c := &WebSocket{
		url:          url,
		pingInterval: pingInterval, // default is 20 seconds
		onMessage:    handler,
	}

	// Apply the provided options
	for _, opt := range options {
		opt(c)
	}

	return c
}

func (b *WebSocket) Connect(args []string) error {
	var err error
	wssUrl := b.url
	if b.maxAliveTime != "" {
		wssUrl += "?max_alive_time=" + b.maxAliveTime
	}
	b.conn, _, err = websocket.DefaultDialer.Dial(b.url, nil)
	if err != nil {
		return err
	}

	if b.requiresAuthentication() {
		if err = b.sendAuth(); err != nil {
			return err
		}
	}

	go b.handleIncomingMessages()

	b.ctx, b.cancel = context.WithCancel(context.Background())
	Ping(b)

	return b.sendSubscription(args)
}

func Ping(b *WebSocket) {
	ticker := time.NewTicker(time.Duration(b.pingInterval) * time.Second)
	go func() {
		defer ticker.Stop() // Ensure the ticker is stopped when this goroutine ends
		for {
			select {
			case <-ticker.C: // Wait until the ticker sends a signal
				if err := b.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
					fmt.Println("Failed to send ping:", err)
				}
			case <-b.ctx.Done():
				fmt.Println("Exit ping")
				return
			}
		}
	}()
}

func (b *WebSocket) Disconnect() error {
	b.cancel()
	return b.conn.Close()
}

func (b *WebSocket) Send(message string) error {
	return b.conn.WriteMessage(websocket.TextMessage, []byte(message))
}

func (b *WebSocket) requiresAuthentication() bool {
	return b.url == WEBSOCKET_PRIVATE_MAINNET ||
		b.url == WEBSOCKET_PRIVATE_TESTNET ||
		b.url == V3_CONTRACT_PRIVATE ||
		b.url == V3_UNIFIED_PRIVATE ||
		b.url == V3_SPOT_PRIVATE
}

func (b *WebSocket) sendAuth() error {
	// Get current Unix time in milliseconds
	expires := time.Now().UnixNano()/1e6 + 10000
	val := fmt.Sprintf("GET/realtime%d", expires)

	h := hmac.New(sha256.New, []byte(b.apiSecret))
	h.Write([]byte(val))

	// Convert to hexadecimal instead of base64
	signature := hex.EncodeToString(h.Sum(nil))
	fmt.Println("signature generated : " + signature)

	authMessage := map[string]interface{}{
		"req_id": uuid.New(),
		"op":     "auth",
		"args":   []interface{}{b.apiKey, expires, signature},
	}
	fmt.Println("auth args:", fmt.Sprintf("%v", authMessage["args"]))
	return b.SendAsJson(authMessage)
}

func (b *WebSocket) sendSubscription(args []string) error {
	subMessage := map[string]interface{}{
		"req_id": uuid.New(),
		"op":     "subscribe",
		"args":   args,
	}
	fmt.Println("subscribe msg:", fmt.Sprintf("%v", subMessage["args"]))
	return b.SendAsJson(subMessage)
}

func (b *WebSocket) SendAsJson(v interface{}) error {
	data, err := json.Marshal(v)
	if err != nil {
		return err
	}
	return b.Send(string(data))
}