luhn-algorithm/Src/Luhn.php at main · TheWebSolver/luhn-algorithm · GitHub

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<?php

declare( strict_types = 1 );

namespace TheWebSolver\Codegarage\Validator;

use LogicException;

trait Luhn {

private const ALLOWED_PATTERN = '/[^0-9]/';

private const EMPTY_VALUE = 'REPRESENTS EMPTY CHECKSUM VALUE @Luhn';

private bool $needsDoubling = false;

private string $digits = '0';

private int $checksum;

private mixed $raw;

/** @var array<int,array{doubled:bool,result:int}> */

private array $state;

public function __construct( mixed $value = null ) {

if ( $value ) {

$this->runAlgorithm( $value );

}

/** @throws LogicException When initialized without value. */

public function __toString(): string {

return ( $this->isValid() ? '' : 'in' ) . "valid [#{$this->digits}] checksum:{$this->checksum}";

}

/** @throws LogicException When initialized without value or constructor value & invoked value mismatch. */

public function __invoke( mixed $data = null ): bool {

return $this->ensureNumber( $data ?? self::EMPTY_VALUE )->isValid();

}

/**

* @return array{isValid:bool,digits:int,checksum:int,state:array<int,array{doubled:bool,result:int}>}

* @throws LogicException When initialized without value.

public function __debugInfo(): array {

return [

'isValid' => $this->isValid(),

'digits' => (int) $this->digits,

'checksum' => $this->checksum(),

'state' => array_reverse( $this->state ?? [] ),

];

}

/** @throws LogicException When initialized with empty value. */

public static function validate( mixed $value ): bool {

return ( new self( $value ) )();

}

/** @throws LogicException When initialized without value. */

public function checksum(): int {

return $this->checksum ??= $this->ensureNumber( $this->raw ?? self::EMPTY_VALUE )->add();

}

/** @throws LogicException When initialized without value. */

public function isValid(): bool {

return 0 === $this->checksum() % 10;

}

public static function normalize( string $value ): string {

return preg_replace( self::ALLOWED_PATTERN, replacement: '', subject: $value ) ?? '';

}

private function runAlgorithm( mixed $value ): static {

$this->raw = $value;

return ! is_scalar( $value ) || ! ( $v = self::normalize( (string) $value ) ) || 2 > ( $l = strlen( $v ) )

? $this

: $this->computeDigitsFrom( value: $v, length: $l - 1 );

}

private function computeDigitsFrom( string $value, int $length, string $final = '' ): static {

// Start doubling every second digit from the end of the given value.

for ( $i = $length; $i >= 0; --$i ) {

$this->runAlgorithmFor( $value, step: $i, carry: $final );

}

$this->digits = strrev( $final );

return $this;

}

private function runAlgorithmFor( string $value, int $step, string &$carry ): void {

$current = $value[ $step ];

$doubled = $this->needsDoubling;

$carry .= $result = $this->maybeDoubleAndAddDigits( value: (int) $current );

$this->state[ $step ] = compact( 'doubled', 'result' );

}

private function add(): int {

return (int) array_sum( array: str_split( $this->digits ) );

}

private function maybeDoubleAndAddDigits( int $value ): int {

$double = $this->needsDoubling;

$this->needsDoubling = ! $double;

return ! $double ? $value : ( ( $doubled = $value * 2 ) > 9 ? ( $doubled % 10 ) + 1 : $doubled );

}

private function ensureNumber( mixed $value ): static {

if ( ! isset( $this->raw ) ) {

return self::EMPTY_VALUE !== $value ? $this->runAlgorithm( $value ) : $this->throw( hasValue: false );

}

return ( self::EMPTY_VALUE === $value || $this->raw === $value ) ? $this : $this->throw( hasValue: true );

}

private function throw( bool $hasValue ): never {

$valueError = $hasValue ? 'Initialized value does not match with invoked value' : 'Value not provided';

throw new LogicException( $valueError . ' for Luhn validation.' );

}

luhn-algorithm/Src/Luhn.php at main · TheWebSolver/luhn-algorithm · GitHub

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