package payments

import (
	"context"
	"fmt"

	"github.com/mercadopago/sdk-go/pkg/config"
	"github.com/mercadopago/sdk-go/pkg/preference"
	"github.com/saveinmed/backend-go/internal/domain"
)

type MercadoPagoGateway struct {
	BaseURL               string
	AccessToken           string
	BackendURL            string
	MarketplaceCommission float64
}

func NewMercadoPagoGateway(baseURL, accessToken, backendURL string, commission float64) *MercadoPagoGateway {
	return &MercadoPagoGateway{
		BaseURL:               baseURL,
		AccessToken:           accessToken,
		BackendURL:            backendURL,
		MarketplaceCommission: commission,
	}
}

func (g *MercadoPagoGateway) CreatePreference(ctx context.Context, order *domain.Order) (*domain.PaymentPreference, error) {
	cfg, err := config.New(g.AccessToken)
	if err != nil {
		return nil, fmt.Errorf("failed to create mp config: %w", err)
	}

	client := preference.NewClient(cfg)

	var items []preference.ItemRequest
	for _, i := range order.Items {
		items = append(items, preference.ItemRequest{
			ID:          i.ProductID.String(),
			Title:       "Produto", // Fallback as we might not have product details loaded here
			Description: fmt.Sprintf("Product ID %s", i.ProductID),
			Quantity:    int(i.Quantity),
			UnitPrice:   float64(i.UnitCents) / 100.0,
			CurrencyID:  "BRL",
		})
	}

	shipmentCost := float64(order.ShippingFeeCents) / 100.0
	notificationURL := g.BackendURL + "/api/v1/payments/webhook"

	request := preference.Request{
		Items: items,
		Shipments: &preference.ShipmentsRequest{
			Cost: shipmentCost,
			Mode: "not_specified",
		},
		ExternalReference: order.ID.String(),
		NotificationURL:   notificationURL,
		BinaryMode:        true,
		BackURLs: &preference.BackURLsRequest{
			Success: g.BackendURL + "/checkout/success", // Adjust if frontend is on different host? Usually same domain or configured.
			Failure: g.BackendURL + "/checkout/failure",
			Pending: g.BackendURL + "/checkout/pending",
		},
		AutoReturn: "approved",
	}

	pref, err := client.Create(ctx, request)
	if err != nil {
		return nil, fmt.Errorf("failed to create preference: %w", err)
	}

	svcFee := int64(float64(order.TotalCents) * (g.MarketplaceCommission / 100))
	sellerRec := order.TotalCents - svcFee

	return &domain.PaymentPreference{
		OrderID:          order.ID,
		Gateway:          "mercadopago",
		PaymentID:        pref.ID,
		PaymentURL:       pref.InitPoint, // Use SandboxInitPoint if testing? SDK returns proper one based on AccessToken type usually.
		CommissionPct:    g.MarketplaceCommission,
		MarketplaceFee:   svcFee,
		SellerReceivable: sellerRec,
	}, nil
}