package services

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"time"

	"github.com/google/uuid"
	"github.com/stripe/stripe-go/v76"
	"github.com/stripe/stripe-go/v76/checkout/session"
	"github.com/stripe/stripe-go/v76/customer"
	"github.com/stripe/stripe-go/v76/webhook"
	"gorm.io/gorm"
)

type StripeService struct {
	db     *gorm.DB
	config *config.Config
}

func NewStripeService(db *gorm.DB, config *config.Config) *StripeService {
	stripe.Key = config.Stripe.SecretKey
	
	return &StripeService{
		db:     db,
		config: config,
	}
}

func (s *StripeService) CreateCheckoutSession(email, domainName string) (string, error) {
	// Validate inputs
	if email == "" || domainName == "" {
		return "", fmt.Errorf("email and domain name are required")
	}

	// Create or retrieve customer
	customerParams := &stripe.CustomerParams{
		Email: stripe.String(email),
		Metadata: map[string]string{
			"domain_name": domainName,
			"source": "ydn_platform",
		},
	}

	cust, err := customer.New(customerParams)
	if err != nil {
		return "", fmt.Errorf("failed to create customer: %w", err)
	}

	// Create checkout session with proper URLs
	successURL := fmt.Sprintf("https://%s/success?session_id={CHECKOUT_SESSION_ID}", getEnvOrDefault("DOMAIN", "yourdreamnamehere.com"))
	cancelURL := fmt.Sprintf("https://%s/cancel", getEnvOrDefault("DOMAIN", "yourdreamnamehere.com"))

	params := &stripe.CheckoutSessionParams{
		Customer: stripe.String(cust.ID),
		PaymentMethodTypes: stripe.StringSlice([]string{"card"}),
		LineItems: []*stripe.CheckoutSessionLineItemParams{
			{
				Price:    stripe.String(s.config.Stripe.PriceID),
				Quantity: stripe.Int64(1),
			},
		},
		Mode: stripe.String(string(stripe.CheckoutSessionModeSubscription)),
		SuccessURL: stripe.String(successURL),
		CancelURL:  stripe.String(cancelURL),
		AllowPromotionCodes: stripe.Bool(true),
		BillingAddressCollection: stripe.String("required"),
		Metadata: map[string]string{
			"domain_name":    domainName,
			"customer_email": email,
		},
	}

	sess, err := session.New(params)
	if err != nil {
		return "", fmt.Errorf("failed to create checkout session: %w", err)
	}

	// Store customer in database with transaction
	err = s.db.Transaction(func(tx *gorm.DB) error {
		// Check if customer already exists
		var existingCustomer models.Customer
		if err := tx.Where("stripe_id = ?", cust.ID).First(&existingCustomer).Error; err == nil {
			// Update existing customer
			existingCustomer.Email = email
			existingCustomer.Status = "pending"
			return tx.Save(&existingCustomer).Error
		}

		// Create new customer record
		dbCustomer := &models.Customer{
			StripeID: cust.ID,
			Email:    email,
			Status:   "pending", // Will be updated to active after payment
		}

		return tx.Create(dbCustomer).Error
	})

	if err != nil {
		log.Printf("Warning: failed to create customer in database: %v", err)
		// Continue anyway as the Stripe session was created successfully
	}

	log.Printf("Created checkout session %s for customer %s (%s)", sess.ID, cust.ID, email)
	return sess.URL, nil
}

func (s *StripeService) HandleWebhook(signature string, body []byte) (*stripe.Event, error) {
	// Validate inputs
	if signature == "" {
		return nil, fmt.Errorf("webhook signature is required")
	}
	if len(body) == 0 {
		return nil, fmt.Errorf("webhook body is empty")
	}

	// Verify webhook signature
	event, err := webhook.ConstructEvent(body, signature, s.config.Stripe.WebhookSecret)
	if err != nil {
		log.Printf("Webhook signature verification failed: %v", err)
		return nil, fmt.Errorf("webhook signature verification failed: %w", err)
	}

	// Log webhook receipt for debugging
	log.Printf("Received webhook event: %s (ID: %s)", event.Type, event.ID)

	// Process the event
	if err := s.processWebhookEvent(&event); err != nil {
		log.Printf("Failed to process webhook event %s: %v", event.ID, err)
		return nil, fmt.Errorf("failed to process webhook event: %w", err)
	}

	return &event, nil
}

func (s *StripeService) processWebhookEvent(event *stripe.Event) error {
	switch event.Type {
	case "checkout.session.completed":
		return s.handleCheckoutCompleted(event)
	case "invoice.payment_succeeded":
		return s.handleInvoicePaymentSucceeded(event)
	case "invoice.payment_failed":
		return s.handleInvoicePaymentFailed(event)
	case "customer.subscription.created":
		return s.handleSubscriptionCreated(event)
	case "customer.subscription.updated":
		return s.handleSubscriptionUpdated(event)
	case "customer.subscription.deleted":
		return s.handleSubscriptionDeleted(event)
	default:
		log.Printf("Unhandled webhook event type: %s", event.Type)
		return nil
	}
}

func (s *StripeService) handleCheckoutCompleted(event *stripe.Event) error {
	var checkoutSession stripe.CheckoutSession
	if err := json.Unmarshal(event.Data.Raw, &checkoutSession); err != nil {
		return fmt.Errorf("failed to parse checkout session: %w", err)
	}

	log.Printf("Processing completed checkout session: %s", checkoutSession.ID)

	// Extract metadata
	domainName := checkoutSession.Metadata["domain_name"]
	customerEmail := checkoutSession.Metadata["customer_email"]

	if domainName == "" || customerEmail == "" {
		return fmt.Errorf("missing required metadata in checkout session")
	}

	// Update customer status and create subscription record
	return s.db.Transaction(func(tx *gorm.DB) error {
		// Update customer status
		if err := tx.Model(&models.Customer{}).
			Where("stripe_id = ?", checkoutSession.Customer.ID).
			Update("status", "active").Error; err != nil {
			return fmt.Errorf("failed to update customer status: %w", err)
		}

		// Create subscription record if available
		if checkoutSession.Subscription != nil {
			subscription := checkoutSession.Subscription
			customerUUID, _ := uuid.Parse(checkoutSession.Customer.ID) // Convert string to UUID
			dbSubscription := &models.Subscription{
				CustomerID:          customerUUID,
				StripeID:            subscription.ID,
				Status:              string(subscription.Status),
				PriceID:             subscription.Items.Data[0].Price.ID,
				Amount:              float64(subscription.Items.Data[0].Price.UnitAmount) / 100.0,
				Currency:           string(subscription.Items.Data[0].Price.Currency),
				Interval:           string(subscription.Items.Data[0].Price.Recurring.Interval),
				CurrentPeriodStart: time.Unix(subscription.CurrentPeriodStart, 0),
				CurrentPeriodEnd:   time.Unix(subscription.CurrentPeriodEnd, 0),
				CancelAtPeriodEnd:  subscription.CancelAtPeriodEnd,
			}

			if err := tx.Create(dbSubscription).Error; err != nil {
				return fmt.Errorf("failed to create subscription: %w", err)
			}
		}

		log.Printf("Successfully processed checkout completion for domain: %s", domainName)
		return nil
	})
}

func (s *StripeService) handleInvoicePaymentSucceeded(event *stripe.Event) error {
	// Handle successful invoice payment
	log.Printf("Invoice payment succeeded for event: %s", event.ID)
	return nil
}

func (s *StripeService) handleInvoicePaymentFailed(event *stripe.Event) error {
	// Handle failed invoice payment
	log.Printf("Invoice payment failed for event: %s", event.ID)
	
	// Update customer status
	var invoice stripe.Invoice
	if err := json.Unmarshal(event.Data.Raw, &invoice); err != nil {
		return fmt.Errorf("failed to parse invoice: %w", err)
	}

	if err := s.db.Model(&models.Customer{}).
		Where("stripe_id = ?", invoice.Customer.ID).
		Update("status", "past_due").Error; err != nil {
		log.Printf("Failed to update customer status to past_due: %v", err)
	}

	return nil
}

func (s *StripeService) handleSubscriptionCreated(event *stripe.Event) error {
	log.Printf("Subscription created for event: %s", event.ID)
	return nil
}

func (s *StripeService) handleSubscriptionUpdated(event *stripe.Event) error {
	var subscription stripe.Subscription
	if err := json.Unmarshal(event.Data.Raw, &subscription); err != nil {
		return fmt.Errorf("failed to parse subscription: %w", err)
	}

	// Update subscription in database
	updates := map[string]interface{}{
		"status":               string(subscription.Status),
		"current_period_start": time.Unix(subscription.CurrentPeriodStart, 0),
		"current_period_end":   time.Unix(subscription.CurrentPeriodEnd, 0),
		"cancel_at_period_end": subscription.CancelAtPeriodEnd,
	}

	if subscription.CanceledAt > 0 {
		canceledAt := time.Unix(subscription.CanceledAt, 0)
		updates["canceled_at"] = &canceledAt
	}

	if err := s.db.Model(&models.Subscription{}).
		Where("stripe_id = ?", subscription.ID).
		Updates(updates).Error; err != nil {
		log.Printf("Failed to update subscription: %v", err)
	}

	return nil
}

func (s *StripeService) handleSubscriptionDeleted(event *stripe.Event) error {
	var subscription stripe.Subscription
	if err := json.Unmarshal(event.Data.Raw, &subscription); err != nil {
		return fmt.Errorf("failed to parse subscription: %w", err)
	}

	// Soft delete subscription
	if err := s.db.Model(&models.Subscription{}).
		Where("stripe_id = ?", subscription.ID).
		Update("status", "canceled").Error; err != nil {
		log.Printf("Failed to update subscription status to canceled: %v", err)
	}

	return nil
}

func (s *StripeService) CancelSubscription(subscriptionID string) error {
	_, err := subscription.Get(subscriptionID, nil)
	if err != nil {
		return fmt.Errorf("failed to retrieve subscription: %w", err)
	}

	// Cancel at period end
	params := &stripe.SubscriptionParams{
		CancelAtPeriodEnd: stripe.Bool(true),
	}
	_, err = subscription.Update(subscriptionID, params)
	if err != nil {
		return fmt.Errorf("failed to cancel subscription: %w", err)
	}

	// Update database
	if err := s.db.Model(&models.Subscription{}).
		Where("stripe_id = ?", subscriptionID).
		Update("cancel_at_period_end", true).Error; err != nil {
		log.Printf("Warning: failed to update subscription in database: %v", err)
	}

	return nil
}

func (s *StripeService) ProcessCheckoutCompleted(session *stripe.CheckoutSession) error {
	// Extract metadata
	domainName := session.Metadata["domain_name"]
	customerEmail := session.Metadata["customer_email"]

	if domainName == "" || customerEmail == "" {
		return fmt.Errorf("missing required metadata")
	}

	// Create domain record
	domain := &models.Domain{
		Name:   domainName,
		Status: "pending",
	}

	// Find or create customer
	var dbCustomer models.Customer
	if err := s.db.Where("stripe_id = ?", session.Customer.ID).First(&dbCustomer).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			// Create customer record
			dbCustomer = models.Customer{
				StripeID: session.Customer.ID,
				Email:    customerEmail,
				Status:   "active",
			}
			if err := s.db.Create(&dbCustomer).Error; err != nil {
				return fmt.Errorf("failed to create customer: %w", err)
			}
		} else {
			return fmt.Errorf("failed to query customer: %w", err)
		}
	}

	domain.CustomerID = dbCustomer.ID
	if err := s.db.Create(domain).Error; err != nil {
		return fmt.Errorf("failed to create domain: %w", err)
	}

	// Create subscription record
	if session.Subscription != nil {
		subscription := session.Subscription
		dbSubscription := &models.Subscription{
			CustomerID:          dbCustomer.ID,
			StripeID:            subscription.ID,
			Status:              string(subscription.Status),
			CurrentPeriodStart:  time.Unix(subscription.CurrentPeriodStart, 0),
			CurrentPeriodEnd:    time.Unix(subscription.CurrentPeriodEnd, 0),
			CancelAtPeriodEnd:   subscription.CancelAtPeriodEnd,
		}

		if err := s.db.Create(dbSubscription).Error; err != nil {
			return fmt.Errorf("failed to create subscription: %w", err)
		}
	}

	log.Printf("Successfully processed checkout completion for domain: %s", domainName)
	return nil
}

func (s *StripeService) ProcessSubscriptionUpdate(subscription *stripe.Subscription) error {
	// Update subscription in database
	updates := map[string]interface{}{
		"status":               string(subscription.Status),
		"current_period_start": time.Unix(subscription.CurrentPeriodStart, 0),
		"current_period_end":   time.Unix(subscription.CurrentPeriodEnd, 0),
		"cancel_at_period_end": subscription.CancelAtPeriodEnd,
	}

	if err := s.db.Model(&models.Subscription{}).
		Where("stripe_id = ?", subscription.ID).
		Updates(updates).Error; err != nil {
		return fmt.Errorf("failed to update subscription: %w", err)
	}

	log.Printf("Successfully updated subscription: %s", subscription.ID)
	return nil
}