package handlers

import (
	"fmt"
	"log"
	"net/http"
	"net/url"
	"strings"

	"github.com/gin-gonic/gin"

	"mengyastore-backend/internal/auth"
	"mengyastore-backend/internal/email"
	"mengyastore-backend/internal/models"
	"mengyastore-backend/internal/storage"
)

const qrSize = "320x320"

type OrderHandler struct {
	productStore *storage.JSONStore
	orderStore   *storage.OrderStore
	siteStore    *storage.SiteStore
	authClient   *auth.SproutGateClient
}

type checkoutPayload struct {
	ProductID    string `json:"productId"`
	Quantity     int    `json:"quantity"`
	Note         string `json:"note"`
	ContactPhone string `json:"contactPhone"`
	ContactEmail string `json:"contactEmail"`
	NotifyEmail  string `json:"notifyEmail"`
}

func NewOrderHandler(productStore *storage.JSONStore, orderStore *storage.OrderStore, siteStore *storage.SiteStore, authClient *auth.SproutGateClient) *OrderHandler {
	return &OrderHandler{productStore: productStore, orderStore: orderStore, siteStore: siteStore, authClient: authClient}
}

func (h *OrderHandler) sendOrderNotify(toEmail, toName, productName, orderID string, qty int, codes []string, isManual bool) {
	if toEmail == "" {
		return
	}
	cfg, err := h.siteStore.GetSMTPConfig()
	if err != nil || !cfg.IsConfiguredEmail() {
		return
	}
	go func() {
		emailCfg := email.Config{
			SMTPHost: cfg.Host,
			SMTPPort: cfg.Port,
			From:     cfg.Email,
			Password: cfg.Password,
			FromName: cfg.FromName,
		}
		if err := email.SendOrderNotify(emailCfg, email.OrderNotifyData{
			ToEmail:     toEmail,
			ToName:      toName,
			ProductName: productName,
			OrderID:     orderID,
			Quantity:    qty,
			Codes:       codes,
			IsManual:    isManual,
		}); err != nil {
			log.Printf("[Email] 发送通知失败 order=%s to=%s: %v", orderID, toEmail, err)
		} else {
			log.Printf("[Email] 发送通知成功 order=%s to=%s", orderID, toEmail)
		}
	}()
}

func (h *OrderHandler) tryExtractUserWithEmail(c *gin.Context) (account, username, userEmail string) {
	authHeader := c.GetHeader("Authorization")
	if authHeader == "" || !strings.HasPrefix(authHeader, "Bearer ") {
		return "", "", ""
	}
	userToken := strings.TrimPrefix(authHeader, "Bearer ")
	result, err := h.authClient.VerifyToken(userToken)
	if err != nil || !result.Valid || result.User == nil {
		return "", "", ""
	}
	return result.User.Account, result.User.Username, result.User.Email
}

func (h *OrderHandler) CreateOrder(c *gin.Context) {
	userAccount, userName, userEmail := h.tryExtractUserWithEmail(c)

	var payload checkoutPayload
	if err := c.ShouldBindJSON(&payload); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid payload"})
		return
	}

	payload.ProductID = strings.TrimSpace(payload.ProductID)
	if payload.ProductID == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "missing required fields"})
		return
	}
	if payload.Quantity <= 0 {
		payload.Quantity = 1
	}

	product, err := h.productStore.GetByID(payload.ProductID)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
		return
	}
	if !product.Active {
		c.JSON(http.StatusBadRequest, gin.H{"error": "product is not available"})
		return
	}

	if product.RequireLogin && userAccount == "" {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "该商品需要登录后才能购买"})
		return
	}

	if product.MaxPerAccount > 0 && userAccount != "" {
		purchased, err := h.orderStore.CountPurchasedByAccount(userAccount, product.ID)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
			return
		}
		if purchased+payload.Quantity > product.MaxPerAccount {
			remain := product.MaxPerAccount - purchased
			if remain <= 0 {
				c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("每个账户最多购买 %d 个，您已达上限", product.MaxPerAccount)})
			} else {
				c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("每个账户最多购买 %d 个，您还可购买 %d 个", product.MaxPerAccount, remain)})
			}
			return
		}
	}

	if product.Quantity < payload.Quantity {
		c.JSON(http.StatusBadRequest, gin.H{"error": "库存不足"})
		return
	}

	isManual := product.DeliveryMode == "manual"

	var deliveredCodes []string
	var updatedProduct models.Product

	if isManual {
		updatedProduct = product
	} else {
		var ok bool
		deliveredCodes, ok = extractCodes(&product, payload.Quantity)
		if !ok {
			c.JSON(http.StatusBadRequest, gin.H{"error": "卡密不足"})
			return
		}
		product.Quantity = len(product.Codes)
		updatedProduct, err = h.productStore.Update(product.ID, product)
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
			return
		}
	}

	deliveryMode := product.DeliveryMode
	if deliveryMode == "" {
		deliveryMode = "auto"
	}

	// Notification email priority:
	// 1. SproutGate account email (logged-in user, most reliable)
	// 2. notifyEmail passed by frontend (also comes from authState.email)
	// 3. contactEmail explicitly filled by user in checkout form
	// 4. empty → skip sending
	notifyEmail := strings.TrimSpace(userEmail)
	if notifyEmail == "" {
		notifyEmail = strings.TrimSpace(payload.NotifyEmail)
	}
	if notifyEmail == "" {
		notifyEmail = strings.TrimSpace(payload.ContactEmail)
	}

	order := models.Order{
		ProductID:      updatedProduct.ID,
		ProductName:    updatedProduct.Name,
		UserAccount:    userAccount,
		UserName:       userName,
		Quantity:       payload.Quantity,
		DeliveredCodes: deliveredCodes,
		Status:         "pending",
		DeliveryMode:   deliveryMode,
		Note:           strings.TrimSpace(payload.Note),
		ContactPhone:   strings.TrimSpace(payload.ContactPhone),
		ContactEmail:   strings.TrimSpace(payload.ContactEmail),
		NotifyEmail:    notifyEmail,
	}
	created, err := h.orderStore.Create(order)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	if !isManual {
		if err := h.productStore.IncrementSold(updatedProduct.ID, payload.Quantity); err != nil {
			log.Printf("[Order] 更新销量失败 (非致命): %v", err)
		}
		// Send delivery notification for auto-delivery orders immediately
		h.sendOrderNotify(notifyEmail, userName, updatedProduct.Name, created.ID, payload.Quantity, deliveredCodes, false)
	} else {
		// For manual delivery, notify user that order is received and pending
		h.sendOrderNotify(notifyEmail, userName, updatedProduct.Name, created.ID, payload.Quantity, nil, true)
	}

	qrPayload := fmt.Sprintf("order:%s:%s", created.ID, created.ProductID)
	qrURL := fmt.Sprintf("https://api.qrserver.com/v1/create-qr-code/?size=%s&data=%s", qrSize, url.QueryEscape(qrPayload))

	c.JSON(http.StatusOK, gin.H{
		"data": gin.H{
			"orderId":    created.ID,
			"qrCodeUrl":  qrURL,
			"productId":  created.ProductID,
			"productQty": created.Quantity,
			"viewCount":  updatedProduct.ViewCount,
			"status":     created.Status,
		},
	})
}

func (h *OrderHandler) ConfirmOrder(c *gin.Context) {
	orderID := c.Param("id")
	order, err := h.orderStore.Confirm(orderID)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
		return
	}

	isManual := order.DeliveryMode == "manual"

	// For manual delivery, send a "delivered" notification when admin confirms
	if isManual {
		confirmNotifyEmail := order.NotifyEmail
		if confirmNotifyEmail == "" {
			confirmNotifyEmail = order.ContactEmail
		}
		h.sendOrderNotify(confirmNotifyEmail, order.UserName, order.ProductName, order.ID, order.Quantity, order.DeliveredCodes, false)
	}

	c.JSON(http.StatusOK, gin.H{
		"data": gin.H{
			"orderId":        order.ID,
			"status":         order.Status,
			"deliveryMode":   order.DeliveryMode,
			"deliveredCodes": order.DeliveredCodes,
			"isManual":       isManual,
		},
	})
}

func (h *OrderHandler) ListMyOrders(c *gin.Context) {
	authHeader := c.GetHeader("Authorization")
	if authHeader == "" || !strings.HasPrefix(authHeader, "Bearer ") {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "请先登录"})
		return
	}
	userToken := strings.TrimPrefix(authHeader, "Bearer ")
	result, err := h.authClient.VerifyToken(userToken)
	if err != nil || !result.Valid || result.User == nil {
		c.JSON(http.StatusUnauthorized, gin.H{"error": "登录已过期，请重新登录"})
		return
	}

	orders, err := h.orderStore.ListByAccount(result.User.Account)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	c.JSON(http.StatusOK, gin.H{"data": orders})
}

func extractCodes(product *models.Product, count int) ([]string, bool) {
	if count <= 0 {
		return nil, false
	}
	if len(product.Codes) < count {
		return nil, false
	}
	delivered := make([]string, count)
	copy(delivered, product.Codes[:count])
	product.Codes = product.Codes[count:]
	return delivered, true
}