package handler

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"net/http"
	"time"

	"soul-api/internal/database"
	"soul-api/internal/model"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

// GET /api/miniprogram/balance 小程序-查询余额
func BalanceGet(c *gin.Context) {
	userID := c.Query("userId")
	if userID == "" {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "缺少 userId"})
		return
	}
	db := database.DB()
	var bal model.UserBalance
	if err := db.Where("user_id = ?", userID).First(&bal).Error; err != nil {
		c.JSON(http.StatusOK, gin.H{"success": true, "data": gin.H{"userId": userID, "balance": 0, "totalRecharged": 0, "totalGifted": 0, "totalRefunded": 0}})
		return
	}
	c.JSON(http.StatusOK, gin.H{"success": true, "data": bal})
}

// POST /api/miniprogram/balance/recharge 小程序-充值（创建充值订单）
func BalanceRecharge(c *gin.Context) {
	var body struct {
		UserID string  `json:"userId" binding:"required"`
		Amount float64 `json:"amount" binding:"required,gt=0"`
	}
	if err := c.ShouldBindJSON(&body); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "参数错误: " + err.Error()})
		return
	}

	db := database.DB()
	orderSN := fmt.Sprintf("BAL_%d", time.Now().UnixNano())

	order := model.Order{
		ID:          orderSN,
		OrderSN:     orderSN,
		UserID:      body.UserID,
		ProductType: "balance_recharge",
		Amount:      body.Amount,
	}
	desc := fmt.Sprintf("余额充值 ¥%.2f", body.Amount)
	status := "pending"
	order.Description = &desc
	order.Status = &status

	if err := db.Create(&order).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"success": false, "error": "创建充值订单失败"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"success": true, "data": gin.H{"orderSn": orderSN, "amount": body.Amount}})
}

// POST /api/miniprogram/balance/recharge/confirm 充值完成回调（内部或手动确认）
func BalanceRechargeConfirm(c *gin.Context) {
	var body struct {
		OrderSN string `json:"orderSn" binding:"required"`
	}
	if err := c.ShouldBindJSON(&body); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "参数错误"})
		return
	}

	db := database.DB()
	var order model.Order
	if err := db.Where("order_sn = ? AND product_type = ?", body.OrderSN, "balance_recharge").First(&order).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"success": false, "error": "订单不存在"})
		return
	}
	if order.Status != nil && *order.Status == "paid" {
		c.JSON(http.StatusOK, gin.H{"success": true, "message": "已确认"})
		return
	}

	err := db.Transaction(func(tx *gorm.DB) error {
		paid := "paid"
		now := time.Now()
		if err := tx.Model(&order).Updates(map[string]interface{}{"status": paid, "pay_time": now}).Error; err != nil {
			return err
		}

		var bal model.UserBalance
		if err := tx.Where("user_id = ?", order.UserID).First(&bal).Error; err != nil {
			bal = model.UserBalance{UserID: order.UserID}
			tx.Create(&bal)
		}
		if err := tx.Model(&bal).Updates(map[string]interface{}{
			"balance":          gorm.Expr("balance + ?", order.Amount),
			"total_recharged":  gorm.Expr("total_recharged + ?", order.Amount),
		}).Error; err != nil {
			return err
		}

		tx.Create(&model.BalanceTransaction{
			UserID:       order.UserID,
			Type:         "recharge",
			Amount:       order.Amount,
			BalanceAfter: bal.Balance + order.Amount,
			RelatedOrder: &order.OrderSN,
			Description:  fmt.Sprintf("充值 ¥%.2f", order.Amount),
		})
		return nil
	})

	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"success": false, "error": "确认失败"})
		return
	}
	c.JSON(http.StatusOK, gin.H{"success": true, "message": "充值成功"})
}

// POST /api/miniprogram/balance/gift 小程序-代付解锁（用余额帮他人解锁章节）
func BalanceGift(c *gin.Context) {
	var body struct {
		GiverID   string `json:"giverId" binding:"required"`
		SectionID string `json:"sectionId" binding:"required"`
	}
	if err := c.ShouldBindJSON(&body); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "参数错误"})
		return
	}

	db := database.DB()

	var chapter model.Chapter
	if err := db.Where("id = ?", body.SectionID).First(&chapter).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"success": false, "error": "章节不存在"})
		return
	}
	price := float64(1)
	if chapter.Price != nil {
		price = *chapter.Price
	}
	if price <= 0 {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "该章节免费，无需代付"})
		return
	}

	var giftCode string
	err := db.Transaction(func(tx *gorm.DB) error {
		var bal model.UserBalance
		if err := tx.Where("user_id = ?", body.GiverID).First(&bal).Error; err != nil || bal.Balance < price {
			return fmt.Errorf("余额不足，当前 ¥%.2f，需要 ¥%.2f", bal.Balance, price)
		}

		if err := tx.Model(&bal).Updates(map[string]interface{}{
			"balance":      gorm.Expr("balance - ?", price),
			"total_gifted": gorm.Expr("total_gifted + ?", price),
		}).Error; err != nil {
			return err
		}

		code := make([]byte, 16)
		rand.Read(code)
		giftCode = hex.EncodeToString(code)

		tx.Create(&model.GiftUnlock{
			GiftCode:  giftCode,
			GiverID:   body.GiverID,
			SectionID: body.SectionID,
			Amount:    price,
			Status:    "pending",
		})

		tx.Create(&model.BalanceTransaction{
			UserID:       body.GiverID,
			Type:         "gift",
			Amount:       -price,
			BalanceAfter: bal.Balance - price,
			SectionID:    &body.SectionID,
			Description:  fmt.Sprintf("代付章节 %s (¥%.2f)", body.SectionID, price),
		})

		return nil
	})

	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"success": true, "data": gin.H{
		"giftCode":  giftCode,
		"sectionId": body.SectionID,
		"amount":    price,
	}})
}

// POST /api/miniprogram/balance/gift/redeem 领取代付礼物
func BalanceGiftRedeem(c *gin.Context) {
	var body struct {
		GiftCode   string `json:"giftCode" binding:"required"`
		ReceiverID string `json:"receiverId" binding:"required"`
	}
	if err := c.ShouldBindJSON(&body); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "参数错误"})
		return
	}

	db := database.DB()
	var gift model.GiftUnlock
	if err := db.Where("gift_code = ?", body.GiftCode).First(&gift).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"success": false, "error": "礼物码无效"})
		return
	}
	if gift.Status != "pending" {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "礼物已被领取"})
		return
	}

	err := db.Transaction(func(tx *gorm.DB) error {
		now := time.Now()
		tx.Model(&gift).Updates(map[string]interface{}{
			"receiver_id": body.ReceiverID,
			"status":      "redeemed",
			"redeemed_at": now,
		})

		orderSN := fmt.Sprintf("GIFT_%s", body.GiftCode[:8])
		paid := "paid"
		desc := fmt.Sprintf("来自好友的代付解锁")
		tx.Create(&model.Order{
			ID:          orderSN,
			OrderSN:     orderSN,
			UserID:      body.ReceiverID,
			ProductType: "section",
			ProductID:   &gift.SectionID,
			Amount:      0,
			Description: &desc,
			Status:      &paid,
			PayTime:     &now,
			ReferrerID:  &gift.GiverID,
		})
		return nil
	})

	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"success": false, "error": "领取失败"})
		return
	}

	c.JSON(http.StatusOK, gin.H{"success": true, "data": gin.H{
		"sectionId": gift.SectionID,
		"message":   "解锁成功！",
	}})
}

// POST /api/miniprogram/balance/refund 申请余额退款（9折）
func BalanceRefund(c *gin.Context) {
	var body struct {
		UserID string  `json:"userId" binding:"required"`
		Amount float64 `json:"amount" binding:"required,gt=0"`
	}
	if err := c.ShouldBindJSON(&body); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "参数错误"})
		return
	}

	db := database.DB()
	refundAmount := body.Amount * 0.9

	err := db.Transaction(func(tx *gorm.DB) error {
		var bal model.UserBalance
		if err := tx.Where("user_id = ?", body.UserID).First(&bal).Error; err != nil || bal.Balance < body.Amount {
			return fmt.Errorf("余额不足")
		}

		if err := tx.Model(&bal).Updates(map[string]interface{}{
			"balance":        gorm.Expr("balance - ?", body.Amount),
			"total_refunded": gorm.Expr("total_refunded + ?", body.Amount),
		}).Error; err != nil {
			return err
		}

		tx.Create(&model.BalanceTransaction{
			UserID:       body.UserID,
			Type:         "refund",
			Amount:       -body.Amount,
			BalanceAfter: bal.Balance - body.Amount,
			Description:  fmt.Sprintf("退款 ¥%.2f（原额 ¥%.2f，9折退回 ¥%.2f）", body.Amount, body.Amount, refundAmount),
		})

		return nil
	})

	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, gin.H{"success": true, "data": gin.H{
		"deducted":     body.Amount,
		"refundAmount": refundAmount,
		"message":      fmt.Sprintf("退款成功，实际退回 ¥%.2f", refundAmount),
	}})
}

// GET /api/miniprogram/balance/transactions 交易记录（含余额变动 + 阅读消费订单）
func BalanceTransactions(c *gin.Context) {
	userID := c.Query("userId")
	if userID == "" {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "缺少 userId"})
		return
	}

	db := database.DB()

	var txns []model.BalanceTransaction
	db.Where("user_id = ?", userID).Order("created_at DESC").Limit(50).Find(&txns)

	var orders []model.Order
	db.Where("user_id = ? AND product_type = ? AND status IN ?", userID, "section", []string{"paid", "completed", "success"}).
		Order("created_at DESC").Limit(50).Find(&orders)

	type txRow struct {
		ID          string      `json:"id"`
		Type        string      `json:"type"`
		Amount      float64     `json:"amount"`
		Description string      `json:"description"`
		CreatedAt   interface{} `json:"createdAt"`
	}

	merged := make([]txRow, 0, len(txns)+len(orders))
	for _, t := range txns {
		merged = append(merged, txRow{
			ID: fmt.Sprintf("bal_%d", t.ID), Type: t.Type, Amount: t.Amount,
			Description: t.Description, CreatedAt: t.CreatedAt,
		})
	}
	for _, o := range orders {
		desc := "阅读消费"
		if o.Description != nil && *o.Description != "" {
			desc = *o.Description
		}
		merged = append(merged, txRow{
			ID: o.ID, Type: "consume", Amount: -o.Amount,
			Description: desc, CreatedAt: o.CreatedAt,
		})
	}

	// 按时间倒序排列
	for i := 0; i < len(merged); i++ {
		for j := i + 1; j < len(merged); j++ {
			ti := fmt.Sprintf("%v", merged[i].CreatedAt)
			tj := fmt.Sprintf("%v", merged[j].CreatedAt)
			if ti < tj {
				merged[i], merged[j] = merged[j], merged[i]
			}
		}
	}
	if len(merged) > 50 {
		merged = merged[:50]
	}

	c.JSON(http.StatusOK, gin.H{"success": true, "data": merged})
}

// GET /api/admin/balance/summary 管理端-余额统计
func BalanceSummary(c *gin.Context) {
	db := database.DB()

	type Summary struct {
		TotalUsers     int64   `json:"totalUsers"`
		TotalBalance   float64 `json:"totalBalance"`
		TotalRecharged float64 `json:"totalRecharged"`
		TotalGifted    float64 `json:"totalGifted"`
		TotalRefunded  float64 `json:"totalRefunded"`
		GiftCount      int64   `json:"giftCount"`
		PendingGifts   int64   `json:"pendingGifts"`
	}

	var s Summary
	db.Model(&model.UserBalance{}).Count(&s.TotalUsers)
	db.Model(&model.UserBalance{}).Select("COALESCE(SUM(balance),0)").Scan(&s.TotalBalance)
	db.Model(&model.UserBalance{}).Select("COALESCE(SUM(total_recharged),0)").Scan(&s.TotalRecharged)
	db.Model(&model.UserBalance{}).Select("COALESCE(SUM(total_gifted),0)").Scan(&s.TotalGifted)
	db.Model(&model.UserBalance{}).Select("COALESCE(SUM(total_refunded),0)").Scan(&s.TotalRefunded)
	db.Model(&model.GiftUnlock{}).Count(&s.GiftCount)
	db.Model(&model.GiftUnlock{}).Where("status = ?", "pending").Count(&s.PendingGifts)

	c.JSON(200, gin.H{"success": true, "data": s})
}

// GET /api/miniprogram/balance/gift/info 查询礼物码信息
func BalanceGiftInfo(c *gin.Context) {
	code := c.Query("code")
	if code == "" {
		c.JSON(http.StatusBadRequest, gin.H{"success": false, "error": "缺少 code"})
		return
	}

	db := database.DB()
	var gift model.GiftUnlock
	if err := db.Where("gift_code = ?", code).First(&gift).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"success": false, "error": "礼物码无效"})
		return
	}

	var chapter model.Chapter
	db.Where("id = ?", gift.SectionID).First(&chapter)

	c.JSON(http.StatusOK, gin.H{"success": true, "data": gin.H{
		"giftCode":     gift.GiftCode,
		"sectionId":    gift.SectionID,
		"sectionTitle": chapter.SectionTitle,
		"amount":       gift.Amount,
		"status":       gift.Status,
		"giverId":      gift.GiverID,
	}})
}