package service

import (
	"context"
	"errors"

	"github.com/google/uuid"

	"apskel-pos-be/internal/constants"
	"apskel-pos-be/internal/contract"
	"apskel-pos-be/internal/models"
	"apskel-pos-be/internal/processor"
	"apskel-pos-be/internal/repository"
)

// CustomerWalletService moves balance on the customer's own request: exchanging
// EnakCoin into EnakPoint (docs/prd-point-coin.md F4).
type CustomerWalletService interface {
	PreviewExchange(ctx context.Context, customerID uuid.UUID, coins int64) *contract.Response
	Exchange(ctx context.Context, customerID uuid.UUID, req *contract.ExchangeCoinsRequest, idempotencyKey string, info models.CustomerPinRequestInfo) *contract.Response
}

type CustomerWalletServiceImpl struct {
	exchanges *processor.WalletExchangeProcessor
}

func NewCustomerWalletService(exchanges *processor.WalletExchangeProcessor) *CustomerWalletServiceImpl {
	return &CustomerWalletServiceImpl{exchanges: exchanges}
}

func (s *CustomerWalletServiceImpl) PreviewExchange(ctx context.Context, customerID uuid.UUID, coins int64) *contract.Response {
	preview, err := s.exchanges.Preview(ctx, customerID, coins)
	if err != nil {
		return walletMoveErrorResponse(err)
	}
	return contract.BuildSuccessResponse(preview)
}

func (s *CustomerWalletServiceImpl) Exchange(ctx context.Context, customerID uuid.UUID, req *contract.ExchangeCoinsRequest, idempotencyKey string, info models.CustomerPinRequestInfo) *contract.Response {
	result, err := s.exchanges.Exchange(ctx, customerID, req.Coins, req.Pin, idempotencyKey, info)
	if err != nil {
		return walletMoveErrorResponse(err)
	}
	return contract.BuildSuccessResponse(result)
}

// walletMoveErrorResponse keeps the PIN codes the apps act on, and tells a refused
// request apart from a server failure.
func walletMoveErrorResponse(err error) *contract.Response {
	var pinErr *processor.PinError
	if errors.As(err, &pinErr) {
		return PinErrorResponse(err)
	}
	code := constants.InternalServerErrorCode
	switch {
	case errors.Is(err, repository.ErrWalletNotFound):
		code = constants.NotFoundErrorCode
	case errors.Is(err, processor.ErrWalletMoveRejected),
		errors.Is(err, processor.ErrWalletIdempotencyConflict),
		errors.Is(err, processor.ErrWalletInvalidEntry):
		code = constants.ValidationErrorCode
	}
	return contract.BuildErrorResponse([]*contract.ResponseError{
		contract.NewResponseError(code, constants.WalletServiceEntity, err.Error()),
	})
}