feat(subscription): support balance purchases

Refs #3071.

controller/subscription.go

@@ -22,6 +22,10 @@ type BillingPreferenceRequest struct {
 	BillingPreference string `json:"billing_preference"`
 }
 
+type SubscriptionBalancePayRequest struct {
+	PlanId int `json:"plan_id"`
+}
+
 // ---- User APIs ----
 
 func GetSubscriptionPlans(c *gin.Context) {
@@ -92,6 +96,25 @@ func UpdateSubscriptionPreference(c *gin.Context) {
 	common.ApiSuccess(c, gin.H{"billing_preference": pref})
 }
 
+func SubscriptionRequestBalancePay(c *gin.Context) {
+	if !requirePaymentCompliance(c) {
+		return
+	}
+
+	userId := c.GetInt("id")
+	var req SubscriptionBalancePayRequest
+	if err := c.ShouldBindJSON(&req); err != nil || req.PlanId <= 0 {
+		common.ApiErrorMsg(c, "参数错误")
+		return
+	}
+
+	if err := model.PurchaseSubscriptionWithBalance(userId, req.PlanId); err != nil {
+		common.ApiError(c, err)
+		return
+	}
+	common.ApiSuccess(c, nil)
+}
+
 // ---- Admin APIs ----
 
 func AdminListSubscriptionPlans(c *gin.Context) {