draft

backend/internal/service/wechat.go

@@ -0,0 +1,161 @@
+package service
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"time"
+
+	"pay-bridge/internal/model"
+	"pay-bridge/internal/repository"
+	"pay-bridge/pkg/crypto"
+)
+
+const (
+	wxTokenURL    = "https://api.weixin.qq.com/cgi-bin/token"
+	wxSendMsgURL  = "https://api.weixin.qq.com/cgi-bin/message/template/send"
+	accessTokenTTL = 90 * time.Minute // 微信 access_token 有效期 2h，提前 30min 刷新
+)
+
+// WechatService 微信模板消息服务
+type WechatService struct {
+	wechatRepo *repository.WechatRepository
+	cryptoKey  string
+	httpClient *http.Client
+	// 内存缓存 access_token，避免频繁调用微信接口
+	tokenCache map[string]*tokenEntry
+}
+
+type tokenEntry struct {
+	token     string
+	expiresAt time.Time
+}
+
+func NewWechatService(wechatRepo *repository.WechatRepository, cryptoKey string) *WechatService {
+	return &WechatService{
+		wechatRepo: wechatRepo,
+		cryptoKey:  cryptoKey,
+		httpClient: &http.Client{Timeout: 10 * time.Second},
+		tokenCache: make(map[string]*tokenEntry),
+	}
+}
+
+// SendPaymentNotify 发送支付成功通知
+func (s *WechatService) SendPaymentNotify(ctx context.Context, appID, tradeNo, openID string, amount int64) error {
+	binding, err := s.wechatRepo.GetBinding(ctx, appID)
+	if err != nil || binding == nil {
+		return nil // 未配置微信通知，跳过
+	}
+
+	data := map[string]any{
+		"trade_no": map[string]string{"value": tradeNo},
+		"amount":   map[string]string{"value": fmt.Sprintf("%.2f 元", float64(amount)/100)},
+		"time":     map[string]string{"value": time.Now().Format("2006-01-02 15:04:05")},
+	}
+
+	return s.sendTemplate(ctx, appID, binding, openID, tradeNo, data)
+}
+
+// sendTemplate 发送模板消息
+func (s *WechatService) sendTemplate(ctx context.Context, appID string, binding *model.WechatBinding,
+	openID, tradeNo string, data map[string]any) error {
+
+	log := &model.WechatMessageLog{
+		AppID:      appID,
+		TradeNo:    tradeNo,
+		OpenID:     openID,
+		TemplateID: binding.TemplateID,
+		Status:     model.WechatMessageStatusPending,
+	}
+	if err := s.wechatRepo.CreateMessageLog(ctx, log); err != nil {
+		return err
+	}
+
+	token, err := s.getAccessToken(ctx, binding)
+	if err != nil {
+		updates := map[string]any{"status": model.WechatMessageStatusFailed, "err_msg": err.Error()}
+		s.wechatRepo.UpdateMessageLog(ctx, log.ID, updates)
+		return err
+	}
+
+	payload := map[string]any{
+		"touser":      openID,
+		"template_id": binding.TemplateID,
+		"data":        data,
+	}
+	body, _ := json.Marshal(payload)
+
+	url := fmt.Sprintf("%s?access_token=%s", wxSendMsgURL, token)
+	resp, err := s.httpClient.Post(url, "application/json", bytes.NewReader(body))
+	if err != nil {
+		updates := map[string]any{"status": model.WechatMessageStatusFailed, "err_msg": err.Error()}
+		s.wechatRepo.UpdateMessageLog(ctx, log.ID, updates)
+		return err
+	}
+	defer resp.Body.Close()
+
+	respBody, _ := io.ReadAll(resp.Body)
+	var result struct {
+		ErrCode int    `json:"errcode"`
+		ErrMsg  string `json:"errmsg"`
+	}
+	json.Unmarshal(respBody, &result)
+
+	now := time.Now()
+	if result.ErrCode == 0 {
+		updates := map[string]any{"status": model.WechatMessageStatusSuccess, "sent_at": now}
+		s.wechatRepo.UpdateMessageLog(ctx, log.ID, updates)
+		slog.InfoContext(ctx, "wechat template sent", "trade_no", tradeNo, "open_id", openID)
+	} else {
+		errMsg := fmt.Sprintf("errcode=%d errmsg=%s", result.ErrCode, result.ErrMsg)
+		updates := map[string]any{"status": model.WechatMessageStatusFailed, "err_msg": errMsg}
+		s.wechatRepo.UpdateMessageLog(ctx, log.ID, updates)
+		return fmt.Errorf("wechat send failed: %s", errMsg)
+	}
+	return nil
+}
+
+// getAccessToken 获取微信 access_token（带内存缓存）
+func (s *WechatService) getAccessToken(ctx context.Context, binding *model.WechatBinding) (string, error) {
+	if entry, ok := s.tokenCache[binding.WxAppID]; ok && time.Now().Before(entry.expiresAt) {
+		return entry.token, nil
+	}
+
+	// 解密 secret
+	secret, err := crypto.Decrypt(binding.WxSecret, s.cryptoKey)
+	if err != nil {
+		return "", fmt.Errorf("decrypt wx secret: %w", err)
+	}
+
+	url := fmt.Sprintf("%s?grant_type=client_credential&appid=%s&secret=%s",
+		wxTokenURL, binding.WxAppID, secret)
+	resp, err := s.httpClient.Get(url)
+	if err != nil {
+		return "", fmt.Errorf("get wx token: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, _ := io.ReadAll(resp.Body)
+	var result struct {
+		AccessToken string `json:"access_token"`
+		ExpiresIn   int    `json:"expires_in"`
+		ErrCode     int    `json:"errcode"`
+		ErrMsg      string `json:"errmsg"`
+	}
+	if err := json.Unmarshal(body, &result); err != nil {
+		return "", err
+	}
+	if result.ErrCode != 0 {
+		return "", fmt.Errorf("wx token error: %d %s", result.ErrCode, result.ErrMsg)
+	}
+
+	s.tokenCache[binding.WxAppID] = &tokenEntry{
+		token:     result.AccessToken,
+		expiresAt: time.Now().Add(accessTokenTTL),
+	}
+	return result.AccessToken, nil
+}