package exchange

import (
	"encoding/json"
	"log"
	"time"
)

// BitgetWS connects to Bitget WebSocket for ticker channel.
type BitgetWS struct {
	Conn    *PriceConnector
	Tracked []string // Bitget symbols like BTCUSDT
}

type bitgetSubscribeMsg struct {
	Op   string          `json:"op"`
	Args []bitgetChannel `json:"args"`
}

type bitgetChannel struct {
	InstType string `json:"instType"`
	Channel  string `json:"channel"`
	InstID   string `json:"instId"`
}

type bitgetTickerMsg struct {
	Action string            `json:"action"`
	Arg    bitgetChannel     `json:"arg"`
	Data   []bitgetTickerData `json:"data"`
}

type bitgetTickerData struct {
	LastPr string `json:"lastPr"`
	BidPr  string `json:"bidPr"`
	AskPr  string `json:"askPr"`
}

func NewBitgetWS(tracked []string) *BitgetWS {
	return &BitgetWS{
		Tracked: tracked,
	}
}

// Run connects to Bitget WS and streams ticker data.
func (b *BitgetWS) Run(updateFn func(coin string, price, bid, ask float64)) error {
	url := "wss://ws.bitget.com/v2/ws/public"

	b.Conn = NewPriceConnector(url, "Bitget", 120*time.Second, 30*time.Second)
	b.Conn.PingInterval = 25 * time.Second // Bitget requires ping within 30s
	b.Conn.TextPing = true                 // Bitget v2 expects text "ping" message

	b.Conn.OnConnect = func() {
		log.Printf("[Bitget WS] Connected, subscribing (%d symbols)", len(b.Tracked))

		// Batch subscriptions — Bitget WS has a limit per message
		batchSize := 20
		for i := 0; i < len(b.Tracked); i += batchSize {
			end := i + batchSize
			if end > len(b.Tracked) {
				end = len(b.Tracked)
			}
			batch := b.Tracked[i:end]
			args := make([]map[string]string, len(batch))
			for j, sym := range batch {
				args[j] = map[string]string{
					"instType": "USDT-FUTURES",
					"channel":  "ticker",
					"instId":   sym,
				}
			}
			sub := map[string]interface{}{
				"op":   "subscribe",
				"args": args,
			}
			if err := b.Conn.SendJSON(sub); err != nil {
				log.Printf("[Bitget WS] Subscribe error (batch %d): %v", i/batchSize, err)
			}
		}
	}

	b.Conn.OnMessage = func(msg []byte) {
		// Handle Bitget text "pong" response
		if string(msg) == "pong" {
			return
		}

		// Check for Bitget subscription confirmation or error response
		var generic map[string]interface{}
		if err := json.Unmarshal(msg, &generic); err == nil {
			if evt, _ := generic["event"].(string); evt == "error" {
				log.Printf("[Bitget WS] Subscribe error response: %s", string(msg))
				return
			}
		}

		var ticker bitgetTickerMsg
		if err := json.Unmarshal(msg, &ticker); err != nil {
			log.Printf("[Bitget WS] Unrecognized message: %s", string(msg))
			return
		}
		if len(ticker.Data) == 0 || ticker.Data[0].LastPr == "" {
			return
		}

		// Convert BTCUSDT -> BTC
		coin := symbolToCoin(ticker.Arg.InstID, "USDT")
		if coin == "" {
			return
		}

		price := parseFloat(ticker.Data[0].LastPr)
		if price > 0 {
			bid := parseFloat(ticker.Data[0].BidPr)
			ask := parseFloat(ticker.Data[0].AskPr)
			updateFn(coin, price, bid, ask)
		}
	}

	return b.Conn.Run()
}