exchange-monitor-go/exchange/bitget_trade.go

package exchange

import (
	"crypto/hmac"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"math"
	"net/http"
	"strconv"
	"strings"
	"time"
)

type BitgetTrade struct {
	APIKey     string
	APISecret  string
	Passphrase string
	client     *http.Client
	paperMode  bool
}

func NewBitgetTrade(apiKey, apiSecret, passphrase string) *BitgetTrade {
	return &BitgetTrade{
		APIKey:     apiKey,
		APISecret:  apiSecret,
		Passphrase: passphrase,
		client:     &http.Client{Timeout: 10 * time.Second},
		paperMode:  strings.HasPrefix(apiKey, "bg_"),
	}
}

func (b *BitgetTrade) PlaceMarketOrder(side, symbol, size, tradeSide string) (string, error) {
	ts := fmt.Sprintf("%d", time.Now().UnixMilli())
	method := "POST"

	requestPath := "/api/v2/mix/order/place-order"
	host := "https://api.bitget.com"

	body := map[string]interface{}{
		"marginCoin":  "USDT",
		"symbol":      symbol,
		"productType": "USDT-FUTURES",
		"side":        side,
		"orderType":   "market",
		"timeInForce": "IOC",
		"marginMode":  "crossed",
		"tradeSide":   tradeSide,
		"size":        size,
	}
	bodyJSON, _ := json.Marshal(body)

	sign := b.sign(method, requestPath, ts, string(bodyJSON))
	url := host + requestPath
	req, _ := http.NewRequest(method, url, strings.NewReader(string(bodyJSON)))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("ACCESS-KEY", b.APIKey)
	req.Header.Set("ACCESS-SIGN", sign)
	req.Header.Set("ACCESS-TIMESTAMP", ts)
	req.Header.Set("ACCESS-PASSPHRASE", b.Passphrase)
	if b.paperMode {
		req.Header.Set("paptrading", "1")
	}

	resp, err := b.client.Do(req)
	if err != nil {
		return "", fmt.Errorf("http request: %w", err)
	}
	defer resp.Body.Close()
	respBody, _ := io.ReadAll(resp.Body)

	var result struct {
		Code string `json:"code"`
		Msg  string `json:"msg"`
		Data struct {
			OrderID string `json:"orderId"`
		} `json:"data"`
	}
	if err := json.Unmarshal(respBody, &result); err != nil {
		return "", fmt.Errorf("parse: %s", string(respBody))
	}
	if result.Code != "00000" {
		return "", fmt.Errorf("bitget error: %s - %s", result.Code, result.Msg)
	}
	return result.Data.OrderID, nil
}

// GetTradeFee queries the fills endpoint for actual fee charged.
func (b *BitgetTrade) GetTradeFee(symbol, orderID string) (feeUSD float64, err error) {
	ts := fmt.Sprintf("%d", time.Now().UnixMilli())
	method := "GET"
	requestPath := "/api/v2/mix/order/fills?symbol=" + symbol + "&orderId=" + orderID + "&productType=USDT-FUTURES"
	host := "https://api.bitget.com"

	sign := b.sign(method, requestPath, ts, "")
	url := host + requestPath
	req, _ := http.NewRequest(method, url, nil)
	req.Header.Set("ACCESS-KEY", b.APIKey)
	req.Header.Set("ACCESS-SIGN", sign)
	req.Header.Set("ACCESS-TIMESTAMP", ts)
	req.Header.Set("ACCESS-PASSPHRASE", b.Passphrase)
	if b.paperMode {
		req.Header.Set("paptrading", "1")
	}

	resp, err := b.client.Do(req)
	if err != nil {
		return 0, fmt.Errorf("http: %w", err)
	}
	defer resp.Body.Close()
	respBody, _ := io.ReadAll(resp.Body)

	var raw struct {
		Code string            `json:"code"`
		Msg  string            `json:"msg"`
		Data []json.RawMessage `json:"data"`
	}
	if err := json.Unmarshal(respBody, &raw); err != nil {
		return 0, fmt.Errorf("parse: %s", string(respBody))
	}
	if raw.Code != "00000" {
		return 0, fmt.Errorf("bitget error: %s - %s", raw.Code, raw.Msg)
	}

	var totalFee float64
	for _, item := range raw.Data {
		var fill struct {
			FillFee string `json:"fillFee"`
		}
		if err := json.Unmarshal(item, &fill); err != nil {
			continue
		}
		f, _ := strconv.ParseFloat(fill.FillFee, 64)
		totalFee += math.Abs(f)
	}
	return totalFee, nil
}

func (b *BitgetTrade) sign(method, requestPath, timestamp, body string) string {
	raw := timestamp + method + requestPath + body
	mac := hmac.New(sha256.New, []byte(b.APISecret))
	mac.Write([]byte(raw))
	return base64.StdEncoding.EncodeToString(mac.Sum(nil))
}

func (b *BitgetTrade) GetBalance() (float64, error) {
	ts := fmt.Sprintf("%d", time.Now().UnixMilli())
	method := "GET"
	host := "https://api.bitget.com"
	requestPath := "/api/v2/mix/account/accounts?productType=USDT-FUTURES"

	sign := b.sign(method, requestPath, ts, "")
	url := host + requestPath
	req, _ := http.NewRequest(method, url, nil)
	req.Header.Set("ACCESS-KEY", b.APIKey)
	req.Header.Set("ACCESS-SIGN", sign)
	req.Header.Set("ACCESS-TIMESTAMP", ts)
	req.Header.Set("ACCESS-PASSPHRASE", b.Passphrase)
	if b.paperMode {
		req.Header.Set("paptrading", "1")
	}

	resp, err := b.client.Do(req)
	if err != nil {
		return 0, fmt.Errorf("http: %w", err)
	}
	defer resp.Body.Close()
	respBody, _ := io.ReadAll(resp.Body)

	var raw map[string]interface{}
	if err := json.Unmarshal(respBody, &raw); err != nil {
		return 0, fmt.Errorf("parse: %s", string(respBody))
	}
	code, _ := raw["code"].(string)
	if code != "00000" && code != "" {
		msg, _ := raw["msg"].(string)
		return 0, fmt.Errorf("bitget error: %s - %s", code, msg)
	}

	dataRaw, ok := raw["data"]
	if !ok || dataRaw == nil {
		return 0, fmt.Errorf("no data in response")
	}
	dataArr, ok := dataRaw.([]interface{})
	if !ok {
		return 0, fmt.Errorf("unexpected data format")
	}
	for _, item := range dataArr {
		acct, ok := item.(map[string]interface{})
		if !ok {
			continue
		}
		if acct["marginCoin"] == "USDT" {
			bal, _ := strconv.ParseFloat(fmt.Sprint(acct["available"]), 64)
			return bal, nil
		}
	}
	return 0, fmt.Errorf("no USDT account found")
}

func GetBitgetSize(symbol string, amountUSD, price float64) string {
	if amountUSD < 5 {
		amountUSD = 5
	}
	sz := amountUSD / price
	switch symbol {
	case "DOGEUSDT":
		if sz < 1 { sz = 1 }
		return fmt.Sprintf("%.0f", math.Floor(sz))
	case "ONDOUSDT":
		sz = math.Floor(sz*10)/10
		if sz < 0.1 { sz = 0.1 }
		return fmt.Sprintf("%.1f", sz)
	case "OPUSDT":
		sz = math.Floor(sz*10)/10
		if sz < 0.1 { sz = 0.1 }
		return fmt.Sprintf("%.1f", sz)
	case "WIFUSDT":
		sz = math.Floor(sz*10)/10
		if sz < 0.1 { sz = 0.1 }
		return fmt.Sprintf("%.1f", sz)
	case "ARBUSDT":
		sz = math.Floor(sz*100)/100
		if sz < 0.01 { sz = 0.01 }
		return fmt.Sprintf("%.2f", sz)
	default:
		return fmt.Sprintf("%.4f", sz)
	}
}