package repository

import (
	"context"

	"apskel-pos-be/internal/entities"

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

type PaymentOrderItemRepository interface {
	Create(ctx context.Context, paymentOrderItem *entities.PaymentOrderItem) error
	GetByID(ctx context.Context, id uuid.UUID) (*entities.PaymentOrderItem, error)
	GetByPaymentID(ctx context.Context, paymentID uuid.UUID) ([]*entities.PaymentOrderItem, error)
	GetPaidQuantitiesByOrderID(ctx context.Context, orderID uuid.UUID) (map[uuid.UUID]int, error)
	Update(ctx context.Context, paymentOrderItem *entities.PaymentOrderItem) error
	Delete(ctx context.Context, id uuid.UUID) error
}

type PaymentOrderItemRepositoryImpl struct {
	db *gorm.DB
}

func NewPaymentOrderItemRepositoryImpl(db *gorm.DB) *PaymentOrderItemRepositoryImpl {
	return &PaymentOrderItemRepositoryImpl{
		db: db,
	}
}

func (r *PaymentOrderItemRepositoryImpl) Create(ctx context.Context, paymentOrderItem *entities.PaymentOrderItem) error {
	return r.db.WithContext(ctx).Create(paymentOrderItem).Error
}

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

func (r *PaymentOrderItemRepositoryImpl) GetByPaymentID(ctx context.Context, paymentID uuid.UUID) ([]*entities.PaymentOrderItem, error) {
	var paymentOrderItems []*entities.PaymentOrderItem
	err := r.db.WithContext(ctx).
		Preload("Payment").
		Preload("OrderItem").
		Where("payment_id = ?", paymentID).
		Find(&paymentOrderItems).Error
	return paymentOrderItems, err
}

func (r *PaymentOrderItemRepositoryImpl) Update(ctx context.Context, paymentOrderItem *entities.PaymentOrderItem) error {
	return r.db.WithContext(ctx).Save(paymentOrderItem).Error
}

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

// GetPaidQuantitiesByOrderID efficiently aggregates paid quantities for an order using SQL
func (r *PaymentOrderItemRepositoryImpl) GetPaidQuantitiesByOrderID(ctx context.Context, orderID uuid.UUID) (map[uuid.UUID]int, error) {
	type Result struct {
		OrderItemID   uuid.UUID `json:"order_item_id"`
		TotalQuantity int       `json:"total_quantity"`
	}

	var results []Result

	// Efficient SQL query that aggregates quantities in the database
	err := r.db.WithContext(ctx).
		Table("payment_order_items poi").
		Select("poi.order_item_id, SUM(poi.quantity) as total_quantity").
		Joins("JOIN payments p ON poi.payment_id = p.id").
		Where("p.order_id = ?", orderID).
		Group("poi.order_item_id").
		Scan(&results).Error

	if err != nil {
		return nil, err
	}

	// Convert results to map
	paidQuantities := make(map[uuid.UUID]int)
	for _, result := range results {
		paidQuantities[result.OrderItemID] = result.TotalQuantity
	}

	return paidQuantities, nil
}