package validator

import (
	"errors"
	"strings"
	"unicode/utf8"

	"apskel-pos-be/internal/constants"
	"apskel-pos-be/internal/contract"
)

// walletAdjustmentReasonLimit is the size of wallet_transactions.reason.
const walletAdjustmentReasonLimit = 255

// walletCashOutWords are reasons that describe turning balance into money. EnakPoint
// and EnakCoin can never be cashed out, and an adjustment must not be used to record
// that it happened (docs/prd-point-coin.md K7). Words like "tunai" are left out on
// purpose: "paid in cash but the points never arrived" is a legitimate reason.
var walletCashOutWords = []string{"pencairan", "cairkan", "cash out", "cashout", "withdraw"}

type WalletValidator interface {
	ValidateAdjustRequest(req *contract.AdjustCustomerWalletRequest) (error, string)
}

type WalletValidatorImpl struct{}

func NewWalletValidator() *WalletValidatorImpl {
	return &WalletValidatorImpl{}
}

func (v *WalletValidatorImpl) ValidateAdjustRequest(req *contract.AdjustCustomerWalletRequest) (error, string) {
	if req == nil {
		return errors.New("request body is required"), constants.MissingFieldErrorCode
	}

	req.Currency = strings.ToUpper(strings.TrimSpace(req.Currency))
	if req.Currency == "" {
		return errors.New("currency is required"), constants.MissingFieldErrorCode
	}
	if !constants.IsValidWalletCurrency(req.Currency) {
		return errors.New("currency must be POINT or COIN"), constants.MalformedFieldErrorCode
	}

	if req.Amount == 0 {
		return errors.New("amount must not be zero: use a positive amount to add and a negative one to take away"), constants.ValidationErrorCode
	}

	req.Reason = strings.TrimSpace(req.Reason)
	if req.Reason == "" {
		return errors.New("reason is required"), constants.MissingFieldErrorCode
	}
	if utf8.RuneCountInString(req.Reason) > walletAdjustmentReasonLimit {
		return errors.New("reason must be at most 255 characters"), constants.MalformedFieldErrorCode
	}
	lower := strings.ToLower(req.Reason)
	for _, word := range walletCashOutWords {
		if strings.Contains(lower, word) {
			return errors.New("EnakPoint and EnakCoin cannot be cashed out, so an adjustment cannot be for a cash-out"), constants.ValidationErrorCode
		}
	}

	if len(req.IdempotencyKey) > 50 {
		return errors.New("idempotency_key must be at most 50 characters"), constants.MalformedFieldErrorCode
	}
	return nil, ""
}