package repository

import (
	"context"
	"errors"
	"fmt"
	"time"

	"apskel-pos-be/internal/entities"
	"apskel-pos-be/internal/models"

	"github.com/google/uuid"
	"gorm.io/gorm"
)

type PaymentRepository interface {
	Create(ctx context.Context, payment *entities.Payment) error
	GetByID(ctx context.Context, id uuid.UUID) (*entities.Payment, error)
	GetByOrderID(ctx context.Context, orderID uuid.UUID) ([]*entities.Payment, error)
	Update(ctx context.Context, payment *entities.Payment) error
	Delete(ctx context.Context, id uuid.UUID) error
	RefundPayment(ctx context.Context, id uuid.UUID, refundAmount float64, reason string, refundedBy uuid.UUID) error
	UpdateStatus(ctx context.Context, id uuid.UUID, status entities.PaymentTransactionStatus) error
	GetTotalPaidByOrderID(ctx context.Context, orderID uuid.UUID) (float64, error)
}

type PaymentRepositoryImpl struct {
	db *gorm.DB
}

func NewPaymentRepositoryImpl(db *gorm.DB) *PaymentRepositoryImpl {
	return &PaymentRepositoryImpl{
		db: db,
	}
}

func (r *PaymentRepositoryImpl) Create(ctx context.Context, payment *entities.Payment) error {
	return r.db.WithContext(ctx).Create(payment).Error
}

func (r *PaymentRepositoryImpl) GetByID(ctx context.Context, id uuid.UUID) (*entities.Payment, error) {
	var payment entities.Payment
	err := r.db.WithContext(ctx).
		Preload("PaymentMethod").
		Preload("PaymentOrderItems").
		First(&payment, "id = ?", id).Error
	if err != nil {
		return nil, err
	}
	return &payment, nil
}

func (r *PaymentRepositoryImpl) GetByOrderID(ctx context.Context, orderID uuid.UUID) ([]*entities.Payment, error) {
	var payments []*entities.Payment
	err := r.db.WithContext(ctx).
		Preload("PaymentMethod").
		Preload("PaymentOrderItems").
		Where("order_id = ?", orderID).
		Find(&payments).Error
	return payments, err
}

func (r *PaymentRepositoryImpl) Update(ctx context.Context, payment *entities.Payment) error {
	return r.db.WithContext(ctx).Save(payment).Error
}

func (r *PaymentRepositoryImpl) Delete(ctx context.Context, id uuid.UUID) error {
	return r.db.WithContext(ctx).Delete(&entities.Payment{}, "id = ?", id).Error
}

func (r *PaymentRepositoryImpl) RefundPayment(ctx context.Context, id uuid.UUID, refundAmount float64, reason string, refundedBy uuid.UUID) error {
	now := time.Now()
	return r.db.WithContext(ctx).Model(&entities.Payment{}).
		Where("id = ?", id).
		Updates(map[string]interface{}{
			"refund_amount": refundAmount,
			"refund_reason": reason,
			"refunded_at":   now,
			"refunded_by":   refundedBy,
			"status":        entities.PaymentTransactionStatusRefunded,
		}).Error
}

func (r *PaymentRepositoryImpl) UpdateStatus(ctx context.Context, id uuid.UUID, status entities.PaymentTransactionStatus) error {
	return r.db.WithContext(ctx).Model(&entities.Payment{}).
		Where("id = ?", id).
		Update("status", status).Error
}

func (r *PaymentRepositoryImpl) GetTotalPaidByOrderID(ctx context.Context, orderID uuid.UUID) (float64, error) {
	var total float64
	err := r.db.WithContext(ctx).Model(&entities.Payment{}).
		Where("order_id = ? AND status = ?", orderID, entities.PaymentTransactionStatusCompleted).
		Select("COALESCE(SUM(amount), 0)").
		Scan(&total).Error
	return total, err
}

func (r *PaymentRepositoryImpl) CreatePaymentWithInventoryMovement(ctx context.Context, req *models.CreatePaymentRequest, order *entities.Order, totalPaid float64) (*entities.Payment, error) {
	var payment *entities.Payment
	var orderJustCompleted bool

	err := r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		payment = &entities.Payment{
			OrderID:          req.OrderID,
			PaymentMethodID:  req.PaymentMethodID,
			Amount:           req.Amount,
			Status:           entities.PaymentTransactionStatusCompleted,
			TransactionID:    req.TransactionID,
			SplitNumber:      req.SplitNumber,
			SplitTotal:       req.SplitTotal,
			SplitDescription: req.SplitDescription,
			Metadata:         entities.Metadata(req.Metadata),
		}

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

		newTotalPaid := totalPaid + req.Amount
		if newTotalPaid >= order.TotalAmount {
			if order.PaymentStatus != entities.PaymentStatusCompleted {
				orderJustCompleted = true
			}
			if err := tx.Model(&entities.Order{}).Where("id = ?", req.OrderID).Update("payment_status", entities.PaymentStatusCompleted).Error; err != nil {
				return fmt.Errorf("failed to update order payment status: %w", err)
			}

			if err := tx.Model(&entities.Order{}).Where("id = ?", req.OrderID).Update("status", entities.OrderStatusCompleted).Error; err != nil {
				return fmt.Errorf("failed to update order status: %w", err)
			}
		} else {
			if err := tx.Model(&entities.Order{}).Where("id = ?", req.OrderID).Update("payment_status", entities.PaymentStatusPartiallyRefunded).Error; err != nil {
				return fmt.Errorf("failed to update order payment status: %w", err)
			}
		}

		if orderJustCompleted {
			orderItems, err := r.getOrderItemsWithTransaction(tx, req.OrderID)
			if err != nil {
				return fmt.Errorf("failed to get order items for inventory adjustment: %w", err)
			}

			for _, item := range orderItems {
				updatedInventory, err := r.adjustInventoryWithTransaction(tx, item.ProductID, order.OutletID, -item.Quantity)
				if err != nil {
					return fmt.Errorf("failed to adjust inventory for product %s: %w", item.ProductID, err)
				}

				movement := &entities.InventoryMovement{
					OrganizationID:   order.OrganizationID,
					OutletID:         order.OutletID,
					ItemID:           item.ProductID,
					ItemType:         "PRODUCT",
					MovementType:     entities.InventoryMovementTypeSale,
					Quantity:         float64(-item.Quantity),
					PreviousQuantity: float64(updatedInventory.Quantity + item.Quantity), // Add back the quantity that was subtracted
					NewQuantity:      float64(updatedInventory.Quantity),
					UnitCost:         item.UnitCost,
					TotalCost:        float64(item.Quantity) * item.UnitCost,
					ReferenceType: func() *entities.InventoryMovementReferenceType {
						t := entities.InventoryMovementReferenceTypePayment
						return &t
					}(),
					ReferenceID: &payment.ID,
					OrderID:     &order.ID,
					PaymentID:   &payment.ID,
					UserID:      order.UserID,
					Reason:      stringPtr("Sale from order payment"),
					Notes:       stringPtr(fmt.Sprintf("Order: %s, Payment: %s", order.OrderNumber, payment.ID)),
					Metadata:    entities.Metadata{"order_item_id": item.ID},
				}

				if err := r.createInventoryMovementWithTransaction(tx, movement); err != nil {
					return fmt.Errorf("failed to create inventory movement for product %s: %w", item.ProductID, err)
				}
			}
		}

		return nil
	})

	if err != nil {
		return nil, err
	}

	return payment, nil
}

func (r *PaymentRepositoryImpl) RefundPaymentWithInventoryMovement(ctx context.Context, paymentID uuid.UUID, refundAmount float64, reason string, refundedBy uuid.UUID, payment *entities.Payment) error {
	return r.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		if err := r.RefundPayment(ctx, paymentID, refundAmount, reason, refundedBy); err != nil {
			return fmt.Errorf("failed to refund payment: %w", err)
		}

		// Get order for inventory management
		order, err := r.getOrderWithTransaction(tx, payment.OrderID)
		if err != nil {
			return fmt.Errorf("failed to get order: %w", err)
		}

		// Update order refund amount
		order.RefundAmount += refundAmount
		if err := tx.Model(&entities.Order{}).Where("id = ?", order.ID).Update("refund_amount", order.RefundAmount).Error; err != nil {
			return fmt.Errorf("failed to update order refund amount: %w", err)
		}

		refundRatio := refundAmount / payment.Amount

		orderItems, err := r.getOrderItemsWithTransaction(tx, order.ID)
		if err != nil {
			return fmt.Errorf("failed to get order items for inventory adjustment: %w", err)
		}

		for _, item := range orderItems {
			refundedQuantity := int(float64(item.Quantity) * refundRatio)
			if refundedQuantity > 0 {
				updatedInventory, err := r.adjustInventoryWithTransaction(tx, item.ProductID, order.OutletID, refundedQuantity)
				if err != nil {
					return fmt.Errorf("failed to restore inventory for product %s: %w", item.ProductID, err)
				}

				movement := &entities.InventoryMovement{
					OrganizationID:   order.OrganizationID,
					OutletID:         order.OutletID,
					ItemID:           item.ProductID,
					ItemType:         "PRODUCT",
					MovementType:     entities.InventoryMovementTypeRefund,
					Quantity:         float64(refundedQuantity),
					PreviousQuantity: float64(updatedInventory.Quantity - refundedQuantity), // Subtract the quantity that was added
					NewQuantity:      float64(updatedInventory.Quantity),
					UnitCost:         item.UnitCost,
					TotalCost:        float64(refundedQuantity) * item.UnitCost,
					ReferenceType: func() *entities.InventoryMovementReferenceType {
						t := entities.InventoryMovementReferenceTypeRefund
						return &t
					}(),
					ReferenceID: &paymentID,
					OrderID:     &order.ID,
					PaymentID:   &paymentID,
					UserID:      refundedBy,
					Reason:      stringPtr(fmt.Sprintf("Refund: %s", reason)),
					Notes:       stringPtr(fmt.Sprintf("Order: %s, Payment: %s, Refund Amount: %.2f", order.OrderNumber, paymentID, refundAmount)),
					Metadata:    entities.Metadata{"order_item_id": item.ID, "refund_ratio": refundRatio},
				}

				if err := r.createInventoryMovementWithTransaction(tx, movement); err != nil {
					return fmt.Errorf("failed to create inventory movement for refund product %s: %w", item.ProductID, err)
				}
			}
		}

		return nil
	})
}

// Helper methods for transaction operations
func (r *PaymentRepositoryImpl) getOrderWithTransaction(tx *gorm.DB, orderID uuid.UUID) (*entities.Order, error) {
	var order entities.Order
	err := tx.First(&order, "id = ?", orderID).Error
	if err != nil {
		return nil, err
	}
	return &order, nil
}

func (r *PaymentRepositoryImpl) getOrderItemsWithTransaction(tx *gorm.DB, orderID uuid.UUID) ([]*entities.OrderItem, error) {
	var orderItems []*entities.OrderItem
	err := tx.Where("order_id = ?", orderID).Find(&orderItems).Error
	return orderItems, err
}

func (r *PaymentRepositoryImpl) adjustInventoryWithTransaction(tx *gorm.DB, productID, outletID uuid.UUID, delta int) (*entities.Inventory, error) {
	var inventory entities.Inventory

	// Try to find existing inventory
	if err := tx.Where("product_id = ? AND outlet_id = ?", productID, outletID).First(&inventory).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			// Inventory doesn't exist, create it with initial quantity
			inventory = entities.Inventory{
				ProductID:    productID,
				OutletID:     outletID,
				Quantity:     0,
				ReorderLevel: 0,
			}
			if err := tx.Create(&inventory).Error; err != nil {
				return nil, fmt.Errorf("failed to create inventory record: %w", err)
			}
		} else {
			return nil, err
		}
	}

	inventory.UpdateQuantity(delta)
	if err := tx.Save(&inventory).Error; err != nil {
		return nil, err
	}

	return &inventory, nil
}

func (r *PaymentRepositoryImpl) createInventoryMovementWithTransaction(tx *gorm.DB, movement *entities.InventoryMovement) error {
	return tx.Create(movement).Error
}

// Helper function to create string pointer
func stringPtr(s string) *string {
	return &s
}