package eshop

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	"fotbal-club/internal/config"
	"fotbal-club/internal/models"
	"fotbal-club/internal/services/eshop"
	"fotbal-club/pkg/logger"

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

// PaymentProvider represents a minimal interface for payment services used by checkout.
// It is implemented by RevolutService, StripeService and can be satisfied by fakes in tests.
type PaymentProvider interface {
	CreatePayment(order *models.EshopOrder) (*eshop.PaymentResult, error)
}

type CheckoutController struct {
	DB             *gorm.DB
	RevolutService PaymentProvider
	StripeService  *eshop.StripeService
	Config         *config.Config
}

func NewCheckoutController(db *gorm.DB, cfg *config.Config) *CheckoutController {
	return &CheckoutController{
		DB:             db,
		RevolutService: eshop.NewRevolutService(cfg),
		StripeService:  eshop.NewStripeService(cfg),
		Config:         cfg,
	}
}

type CheckoutRequest struct {
	FirstName       string          `json:"first_name" binding:"required"`
	LastName        string          `json:"last_name" binding:"required"`
	Email           string          `json:"email" binding:"required,email"`
	Phone           string          `json:"phone"`
	BillingAddress  json.RawMessage `json:"billing_address"`
	ShippingAddress json.RawMessage `json:"shipping_address"`
	ShippingMethod  string          `json:"shipping_method" binding:"required"`
	// For Packeta, we might receive packet_point_id in shipping_address or separately
}

func (ctrl *CheckoutController) Checkout(c *gin.Context) {
	var req CheckoutRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid request format: " + err.Error()})
		return
	}

	// Validate email format
	if !strings.Contains(req.Email, "@") || !strings.Contains(req.Email, ".") {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid email address"})
		return
	}

	// Validate phone format (basic Czech phone validation)
	if req.Phone != "" {
		// Remove spaces, dashes, parentheses
		phone := strings.ReplaceAll(strings.ReplaceAll(strings.ReplaceAll(req.Phone, " ", ""), "-", ""), "(", "")
		phone = strings.ReplaceAll(phone, ")", "")

		// Check if it starts with +420 or is 9 digits (Czech format)
		if !strings.HasPrefix(phone, "+420") && len(phone) != 9 {
			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid phone number format"})
			return
		}
	}

	// Validate shipping method
	validShippingMethods := []string{"packeta", "courier"}
	isValidShipping := false
	for _, method := range validShippingMethods {
		if req.ShippingMethod == method {
			isValidShipping = true
			break
		}
	}
	if !isValidShipping {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid shipping method"})
		return
	}

	// For Packeta, validate that shipping address contains point ID
	if req.ShippingMethod == "packeta" {
		var pointData struct {
			ID interface{} `json:"id"`
		}
		if err := json.Unmarshal(req.ShippingAddress, &pointData); err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid Packeta point data"})
			return
		}
		if pointData.ID == nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "Packeta point ID is required"})
			return
		}
	}

	// 1. Get Cart
	// Helper to find cart (duplicated from main.go - should be refactored to service)
	// For now, let's just assume we can get it via user or session
	userIDVal, _ := c.Get("userID")
	var userID *uint
	if u, ok := userIDVal.(uint); ok {
		userID = &u
	}
	sessionToken := c.GetHeader("X-Session-Token")
	if sessionToken == "" {
		if cookie, err := c.Request.Cookie("eshop_session_token"); err == nil {
			sessionToken = cookie.Value
		}
	}

	var cart models.EshopCart
	q := ctrl.DB.Preload("Items").Preload("Items.Product").Preload("Items.Variant").Where("completed = ?", false)
	if userID != nil {
		q = q.Where("user_id = ?", *userID)
	} else if sessionToken != "" {
		q = q.Where("session_token = ?", sessionToken)
	} else {
		c.JSON(http.StatusBadRequest, gin.H{"error": "No session identified"})
		return
	}

	if err := q.First(&cart).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			c.JSON(http.StatusNotFound, gin.H{"error": "Cart not found or expired"})
		} else {
			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to retrieve cart"})
		}
		return
	}

	if len(cart.Items) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"error": "Cart is empty"})
		return
	}

	// Validate cart items and check inventory
	for _, item := range cart.Items {
		if item.Quantity <= 0 {
			c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid item quantity"})
			return
		}

		// Check if product still exists and is active
		var product models.EshopProduct
		if err := ctrl.DB.Where("id = ? AND active = ?", item.ProductID, true).First(&product).Error; err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "Product no longer available"})
			return
		}

		// Check variant if exists
		if item.VariantID != nil {
			var variant models.EshopProductVariant
			if err := ctrl.DB.Where("id = ? AND product_id = ?", item.VariantID, item.ProductID).First(&variant).Error; err != nil {
				c.JSON(http.StatusBadRequest, gin.H{"error": "Product variant no longer available"})
				return
			}

			// Check stock for variant (negative values mean unlimited)
			if variant.StockQty >= 0 && variant.StockQty < item.Quantity {
				c.JSON(http.StatusBadRequest, gin.H{"error": "Insufficient stock for product variant"})
				return
			}
		}

		// Verify price hasn't changed
		if item.UnitPriceCents != product.PriceCents {
			// For MVP, we'll allow it but log it
			logger.Warn("Price mismatch for product %d: cart %d vs current %d", item.ProductID, item.UnitPriceCents, product.PriceCents)
		}
	}

	// 2. Calculate totals
	var itemsTotal int64
	for _, item := range cart.Items {
		itemsTotal += item.UnitPriceCents * int64(item.Quantity)
	}

	// Shipping price - simplistic logic for MVP
	var shippingPrice int64 = 0
	if req.ShippingMethod == "packeta" {
		shippingPrice = 7900 // 79 CZK
	} else if req.ShippingMethod == "courier" {
		shippingPrice = 9900 // 99 CZK
	}

	totalAmount := itemsTotal + shippingPrice

	// 3. Create Order
	// Generate order number (e.g. 202510001)
	orderNumber := fmt.Sprintf("%s%d", time.Now().Format("200601"), time.Now().Unix()%100000) // simplified

	order := models.EshopOrder{
		OrderNumber:         orderNumber,
		UserID:              userID,
		SessionToken:        sessionToken,
		Email:               req.Email,
		FirstName:           req.FirstName,
		LastName:            req.LastName,
		BillingAddressJSON:  string(req.BillingAddress),
		ShippingAddressJSON: string(req.ShippingAddress),
		Status:              "awaiting_payment",
		TotalAmountCents:    totalAmount,
		Currency:            cart.Currency,
		ShippingMethod:      req.ShippingMethod,
		ShippingPriceCents:  shippingPrice,
	}

	tx := ctrl.DB.Begin()
	if err := tx.Create(&order).Error; err != nil {
		tx.Rollback()
		logger.Error("Failed to create order: %v", err)
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to create order"})
		return
	}

	// Create items
	for _, cartItem := range cart.Items {
		orderItem := models.EshopOrderItem{
			OrderID:        order.ID,
			ProductID:      cartItem.ProductID,
			VariantID:      cartItem.VariantID,
			Name:           cartItem.Product.Name,
			Quantity:       cartItem.Quantity,
			UnitPriceCents: cartItem.UnitPriceCents,
			Currency:       cartItem.Currency,
			VATRate:        cartItem.Product.VATRate,
		}
		// Add variant name if exists
		if cartItem.Variant != nil {
			orderItem.Name += " (" + cartItem.Variant.Name + ")"
			orderItem.SKU = cartItem.Variant.SKU
		}
		if err := tx.Create(&orderItem).Error; err != nil {
			tx.Rollback()
			logger.Error("Failed to create order item: %v", err)
			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to create order items"})
			return
		}
	}

	// 4. Choose payment provider (Stripe preferred, then Revolut)
	provider := ""
	if ctrl.Config.StripeEnabled {
		provider = "stripe"
	} else if ctrl.Config.RevolutEnabled {
		provider = "revolut"
	}

	var result *eshop.PaymentResult
	var providerErr error

	switch provider {
	case "stripe":
		result, providerErr = ctrl.StripeService.CreatePayment(&order)
	case "revolut":
		result, providerErr = ctrl.RevolutService.CreatePayment(&order)
	}

	// Handle different payment provider responses
	if provider != "" && providerErr == nil && result != nil {
		payment := models.EshopPayment{
			OrderID:           order.ID,
			Provider:          provider,
			ProviderPaymentID: result.ProviderPaymentID,
			Status:            "pending",
			AmountCents:       order.TotalAmountCents,
			Currency:          order.Currency,
			RawPayloadJSON:    result.RawPayloadJSON,
		}
		if err := tx.Create(&payment).Error; err != nil {
			tx.Rollback()
			logger.Error("Failed to create payment record: %v", err)
			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to save payment info"})
			return
		}

		tx.Commit()

		// Different response format based on provider
		response := gin.H{
			"order_id":         order.ID,
			"order_number":     order.OrderNumber,
			"payment_provider": provider,
		}

		if provider == "stripe" {
			// For Stripe, return the client secret for frontend confirmation
			var paymentData map[string]interface{}
			if err := json.Unmarshal([]byte(result.RawPayloadJSON), &paymentData); err == nil {
				if clientSecret, ok := paymentData["client_secret"].(string); ok {
					response["client_secret"] = clientSecret
				}
			}
		} else if strings.TrimSpace(result.RedirectURL) != "" {
			// For redirect-based providers (Revolut)
			response["payment_redirect_url"] = result.RedirectURL
		}

		c.JSON(http.StatusOK, response)
		return
	}

	// If provider was selected but failed or is not implemented yet, log the error
	if provider != "" && providerErr != nil {
		logger.Error("Payment provider error (%s): %v", provider, providerErr)
	}

	// 5. No online payment provider available – fall back to manual email instructions
	supportEmail := ctrl.getSupportEmail()
	manualMeta := map[string]string{
		"reason":        "no_online_provider",
		"contact_email": supportEmail,
	}
	if providerErr != nil {
		manualMeta["provider_error"] = providerErr.Error()
	}
	metaJSON, _ := json.Marshal(manualMeta)

	manualPayment := models.EshopPayment{
		OrderID:        order.ID,
		Provider:       "manual_email",
		Status:         "pending",
		AmountCents:    order.TotalAmountCents,
		Currency:       order.Currency,
		RawPayloadJSON: string(metaJSON),
	}
	if err := tx.Create(&manualPayment).Error; err != nil {
		tx.Rollback()
		logger.Error("Failed to create manual payment record: %v", err)
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to save payment info"})
		return
	}

	tx.Commit()

	c.JSON(http.StatusOK, gin.H{
		"order_id":       order.ID,
		"order_number":   order.OrderNumber,
		"manual_payment": true,
		"contact_email":  supportEmail,
	})
}

// getSupportEmail returns the best support email for manual orders
func (ctrl *CheckoutController) getSupportEmail() string {
	email := strings.TrimSpace(ctrl.Config.ContactEmail)
	if email == "" {
		email = strings.TrimSpace(ctrl.Config.AdminEmail)
	}

	var settings models.EshopSettings
	if err := ctrl.DB.First(&settings).Error; err == nil {
		if se := strings.TrimSpace(settings.SupportEmail); se != "" {
			email = se
		}
	}

	if email == "" {
		// Safe default to avoid returning empty email
		email = "info@example.com"
	}

	return email
}

// GetOrder returns a single order by ID, ensuring the user/session owns it
func (ctrl *CheckoutController) GetOrder(c *gin.Context) {
	id := c.Param("id")

	userIDVal, _ := c.Get("userID")
	var userID *uint
	if u, ok := userIDVal.(uint); ok {
		userID = &u
	}
	sessionToken := c.GetHeader("X-Session-Token")
	if sessionToken == "" {
		if cookie, err := c.Request.Cookie("eshop_session_token"); err == nil {
			sessionToken = cookie.Value
		}
	}

	var order models.EshopOrder
	q := ctrl.DB.Preload("Items").Preload("Payments").Preload("Labels").Where("id = ?", id)

	// Security check: only allow owner to view
	if userID != nil {
		q = q.Where("user_id = ?", *userID)
	} else if sessionToken != "" {
		q = q.Where("session_token = ?", sessionToken)
	} else {
		c.JSON(http.StatusForbidden, gin.H{"error": "Unauthorized"})
		return
	}

	if err := q.First(&order).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "Order not found"})
		return
	}
	c.JSON(http.StatusOK, order)
}

// RevolutWebhook handles asynchronous notifications from Revolut about payment state changes.
// It expects a JSON payload containing order status updates.
func (ctrl *CheckoutController) RevolutWebhook(c *gin.Context) {
	body, err := io.ReadAll(c.Request.Body)
	if err != nil {
		logger.Error("[revolut-webhook] failed to read body: %v", err)
		c.Status(http.StatusOK)
		return
	}

	// Verify webhook signature
	signature := strings.TrimSpace(c.GetHeader("Revolut-Pay-Payload-Signature"))
	revolutService := eshop.NewRevolutService(ctrl.Config)
	valid, err := revolutService.VerifyWebhook(body, signature)
	if err != nil {
		logger.Error("[revolut-webhook] signature verification failed: %v", err)
		c.Status(http.StatusBadRequest)
		return
	}
	if !valid {
		logger.Error("[revolut-webhook] invalid signature")
		c.Status(http.StatusUnauthorized)
		return
	}

	// Parse webhook payload
	webhook, err := revolutService.ParseWebhook(body)
	if err != nil {
		logger.Error("[revolut-webhook] failed to parse JSON: %v", err)
		c.Status(http.StatusOK)
		return
	}

	// Find payment and related order
	tx := ctrl.DB.Begin()
	var payment models.EshopPayment
	if err := tx.Preload("Order").Where("provider = ? AND provider_payment_id = ?", "revolut", webhook.Order.ID).First(&payment).Error; err != nil {
		logger.Error("[revolut-webhook] payment not found for id=%s: %v", webhook.Order.ID, err)
		tx.Rollback()
		c.Status(http.StatusOK)
		return
	}

	order := payment.Order
	if order.ID == 0 {
		logger.Error("[revolut-webhook] loaded payment without order for id=%s", webhook.Order.ID)
		tx.Rollback()
		c.Status(http.StatusOK)
		return
	}

	// Decide new statuses based on Revolut order status
	newPaymentStatus := ""
	newOrderStatus := ""

	switch webhook.Order.Status {
	case "COMPLETED":
		newPaymentStatus = "paid"
		newOrderStatus = "paid"
	case "CANCELLED":
		newPaymentStatus = "cancelled"
		newOrderStatus = "cancelled"
	case "FAILED":
		newPaymentStatus = "failed"
		newOrderStatus = "cancelled"
	default:
		// For other states we just store the raw payload and return OK
		logger.Info("[revolut-webhook] unhandled status %s for payment %s", webhook.Order.Status, webhook.Order.ID)
		if err := tx.Model(&payment).Updates(map[string]interface{}{
			"raw_payload_json": string(body),
			"updated_at":       time.Now(),
		}).Error; err != nil {
			logger.Error("[revolut-webhook] failed to store raw payload for payment %s: %v", webhook.Order.ID, err)
			tx.Rollback()
			c.Status(http.StatusOK)
			return
		}
		tx.Commit()
		c.Status(http.StatusOK)
		return
	}

	// Update payment status
	updates := map[string]interface{}{
		"status":           newPaymentStatus,
		"raw_payload_json": string(body),
		"updated_at":       time.Now(),
	}
	if err := tx.Model(&payment).Updates(updates).Error; err != nil {
		logger.Error("[revolut-webhook] failed to update payment %s: %v", webhook.Order.ID, err)
		tx.Rollback()
		c.Status(http.StatusOK)
		return
	}

	// Update order status if needed
	if order.Status != newOrderStatus {
		if err := tx.Model(&models.EshopOrder{}).
			Where("id = ?", order.ID).
			Update("status", newOrderStatus).Error; err != nil {
			logger.Error("[revolut-webhook] failed to update order %d status: %v", order.ID, err)
			tx.Rollback()
			c.Status(http.StatusOK)
			return
		}

		// Mark cart as completed if order is paid
		if newOrderStatus == "paid" {
			cartQ := tx.Model(&models.EshopCart{}).Where("completed = ?", false)
			if order.UserID != nil {
				cartQ = cartQ.Where("user_id = ?", order.UserID)
			} else {
				cartQ = cartQ.Where("session_token = ?", order.SessionToken)
			}
			if err := cartQ.Update("completed", true).Error; err != nil {
				logger.Error("[revolut-webhook] failed to mark cart as completed for order %d: %v", order.ID, err)
				// Non-fatal, continue
			}
		}
	}

	tx.Commit()
	logger.Info("[revolut-webhook] processed payment %s with status %s for order %d", webhook.Order.ID, webhook.Order.Status, order.ID)
	c.Status(http.StatusOK)
}

// StripeWebhook handles Stripe webhook events
func (ctrl *CheckoutController) StripeWebhook(c *gin.Context) {
	if ctrl.Config.StripeWebhookSecret == "" {
		logger.Error("[stripe-webhook] webhook secret not configured")
		c.JSON(http.StatusServiceUnavailable, gin.H{"error": "Webhook not configured"})
		return
	}

	body, err := io.ReadAll(c.Request.Body)
	if err != nil {
		logger.Error("[stripe-webhook] failed to read webhook body: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid request"})
		return
	}

	signature := c.GetHeader("Stripe-Signature")
	if signature == "" {
		logger.Error("[stripe-webhook] no signature provided")
		c.JSON(http.StatusBadRequest, gin.H{"error": "No signature"})
		return
	}

	// Parse the event
	var event map[string]interface{}
	if err := json.Unmarshal(body, &event); err != nil {
		logger.Error("[stripe-webhook] failed to parse event: %v", err)
		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid JSON"})
		return
	}

	eventType, ok := event["type"].(string)
	if !ok {
		logger.Error("[stripe-webhook] no event type")
		c.JSON(http.StatusBadRequest, gin.H{"error": "No event type"})
		return
	}

	logger.Info("[stripe-webhook] received event: %s", eventType)

	switch eventType {
	case "payment_intent.succeeded":
		ctrl.handleStripePaymentSucceeded(event, c)
	case "payment_intent.payment_failed":
		ctrl.handleStripePaymentFailed(event, c)
	default:
		logger.Info("[stripe-webhook] unhandled event type: %s", eventType)
	}

	c.Status(http.StatusOK)
}

func (ctrl *CheckoutController) handleStripePaymentSucceeded(event map[string]interface{}, c *gin.Context) {
	paymentIntent, ok := event["data"].(map[string]interface{})["object"].(map[string]interface{})
	if !ok {
		logger.Error("[stripe-webhook] invalid payment intent object")
		return
	}

	paymentIntentID, ok := paymentIntent["id"].(string)
	if !ok {
		logger.Error("[stripe-webhook] no payment intent ID")
		return
	}

	metadata, _ := paymentIntent["metadata"].(map[string]interface{})
	orderIDStr, _ := metadata["order_id"].(string)

	if orderIDStr == "" {
		logger.Error("[stripe-webhook] no order ID in payment intent metadata")
		return
	}

	tx := ctrl.DB.Begin()
	defer func() {
		if r := recover(); r != nil {
			tx.Rollback()
		}
	}()

	// Find the payment record
	var payment models.EshopPayment
	if err := tx.Where("provider_payment_id = ? AND provider = ?", paymentIntentID, "stripe").First(&payment).Error; err != nil {
		logger.Error("[stripe-webhook] payment record not found: %v", err)
		tx.Rollback()
		return
	}

	// Update payment status
	payment.Status = "succeeded"
	if err := tx.Save(&payment).Error; err != nil {
		logger.Error("[stripe-webhook] failed to update payment status: %v", err)
		tx.Rollback()
		return
	}

	// Update order status
	if err := tx.Model(&models.EshopOrder{}).Where("id = ?", payment.OrderID).Update("status", "paid").Error; err != nil {
		logger.Error("[stripe-webhook] failed to update order status: %v", err)
		tx.Rollback()
		return
	}

	// Get order for cart completion
	var order models.EshopOrder
	if err := tx.First(&order, payment.OrderID).Error; err != nil {
		logger.Error("[stripe-webhook] failed to get order: %v", err)
		tx.Rollback()
		return
	}

	// Mark cart as completed
	cartQ := tx.Model(&models.EshopCart{}).Where("completed = ?", false)
	if order.UserID != nil {
		cartQ = cartQ.Where("user_id = ?", *order.UserID)
	} else if strings.TrimSpace(order.SessionToken) != "" {
		cartQ = cartQ.Where("session_token = ?", order.SessionToken)
	}
	if err := cartQ.Update("completed", true).Error; err != nil {
		logger.Error("[stripe-webhook] failed to mark cart as completed: %v", err)
		// Non-fatal
	}

	tx.Commit()
	logger.Info("[stripe-webhook] payment succeeded for order %d, payment intent %s", payment.OrderID, paymentIntentID)
}

func (ctrl *CheckoutController) handleStripePaymentFailed(event map[string]interface{}, c *gin.Context) {
	paymentIntent, ok := event["data"].(map[string]interface{})["object"].(map[string]interface{})
	if !ok {
		logger.Error("[stripe-webhook] invalid payment intent object")
		return
	}

	paymentIntentID, ok := paymentIntent["id"].(string)
	if !ok {
		logger.Error("[stripe-webhook] no payment intent ID")
		return
	}

	// Find and update payment record
	var payment models.EshopPayment
	if err := ctrl.DB.Where("provider_payment_id = ? AND provider = ?", paymentIntentID, "stripe").First(&payment).Error; err != nil {
		logger.Error("[stripe-webhook] payment record not found: %v", err)
		return
	}

	payment.Status = "failed"
	if err := ctrl.DB.Save(&payment).Error; err != nil {
		logger.Error("[stripe-webhook] failed to update payment status: %v", err)
		return
	}

	logger.Info("[stripe-webhook] payment failed for order %d, payment intent %s", payment.OrderID, paymentIntentID)
}