package validation

import (
	"errors"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
)

var (
	// ErrZeroAddress is returned when a zero address is provided
	ErrZeroAddress = errors.New("zero address not allowed")

	// ErrNilAddress is returned when a nil address pointer is provided
	ErrNilAddress = errors.New("nil address pointer")

	// ErrZeroAmount is returned when a zero amount is provided
	ErrZeroAmount = errors.New("zero amount not allowed")

	// ErrNilAmount is returned when a nil amount pointer is provided
	ErrNilAmount = errors.New("nil amount pointer")

	// ErrNegativeAmount is returned when a negative amount is provided
	ErrNegativeAmount = errors.New("negative amount not allowed")
)

// ValidateAddress validates that an address is not zero
func ValidateAddress(addr common.Address) error {
	if addr == (common.Address{}) {
		return ErrZeroAddress
	}
	return nil
}

// ValidateAddressPtr validates that an address pointer is not nil and not zero
func ValidateAddressPtr(addr *common.Address) error {
	if addr == nil {
		return ErrNilAddress
	}
	if *addr == (common.Address{}) {
		return ErrZeroAddress
	}
	return nil
}

// ValidateAmount validates that an amount is not nil, not zero, and not negative
func ValidateAmount(amount *big.Int) error {
	if amount == nil {
		return ErrNilAmount
	}
	if amount.Sign() == 0 {
		return ErrZeroAmount
	}
	if amount.Sign() < 0 {
		return ErrNegativeAmount
	}
	return nil
}

// ValidateAmountAllowZero validates that an amount is not nil and not negative
// (allows zero amounts for optional parameters)
func ValidateAmountAllowZero(amount *big.Int) error {
	if amount == nil {
		return ErrNilAmount
	}
	if amount.Sign() < 0 {
		return ErrNegativeAmount
	}
	return nil
}

// IsZeroAddress checks if an address is zero without returning an error
func IsZeroAddress(addr common.Address) bool {
	return addr == (common.Address{})
}

// IsZeroAmount checks if an amount is zero or nil without returning an error
func IsZeroAmount(amount *big.Int) bool {
	return amount == nil || amount.Sign() == 0
}