<?php

namespace Ramsey\Uuid\Codec;

use Ramsey\Uuid\Exception\InvalidUuidStringException;
use Ramsey\Uuid\UuidInterface;

use function bin2hex;
use function sprintf;
use function substr;
use function substr_replace;

/**
 * TimestampFirstCombCodec encodes and decodes COMBs, with the timestamp as the
 * first 48 bits
 *
 * In contrast with the TimestampLastCombCodec, the TimestampFirstCombCodec
 * adds the timestamp to the first 48 bits of the COMB. To generate a
 * timestamp-first COMB, set the TimestampFirstCombCodec as the codec, along
 * with the CombGenerator as the random generator.
 *
 * ``` php
 * $factory = new UuidFactory();
 *
 * $factory->setCodec(new TimestampFirstCombCodec($factory->getUuidBuilder()));
 *
 * $factory->setRandomGenerator(new CombGenerator(
 *     $factory->getRandomGenerator(),
 *     $factory->getNumberConverter()
 * ));
 *
 * $timestampFirstComb = $factory->uuid4();
 * ```
 *
 * @link https://www.informit.com/articles/printerfriendly/25862 The Cost of GUIDs as Primary Keys
 *
 * @psalm-immutable
 */
class TimestampFirstCombCodec extends StringCodec
{
    /**
     * @psalm-return non-empty-string
     * @psalm-suppress MoreSpecificReturnType we know that the retrieved `string` is never empty
     * @psalm-suppress LessSpecificReturnStatement we know that the retrieved `string` is never empty
     */
    public function encode($uuid)
    {
        $bytes = $this->swapBytes($uuid->getFields()->getBytes());

        return sprintf(
            '%08s-%04s-%04s-%04s-%012s',
            bin2hex(substr($bytes, 0, 4)),
            bin2hex(substr($bytes, 4, 2)),
            bin2hex(substr($bytes, 6, 2)),
            bin2hex(substr($bytes, 8, 2)),
            bin2hex(substr($bytes, 10))
        );
    }

    /**
     * @psalm-return non-empty-string
     * @psalm-suppress MoreSpecificReturnType we know that the retrieved `string` is never empty
     * @psalm-suppress LessSpecificReturnStatement we know that the retrieved `string` is never empty
     */
    public function encodeBinary($uuid)
    {
        /** @phpstan-ignore-next-line PHPStan complains that this is not a non-empty-string. */
        return $this->swapBytes($uuid->getFields()->getBytes());
    }

    /**
     * @throws InvalidUuidStringException
     *
     * @inheritDoc
     */
    public function decode($encodedUuid)
    {
        $bytes = $this->getBytes($encodedUuid);

        return $this->getBuilder()->build($this, $this->swapBytes($bytes));
    }

    public function decodeBytes($bytes)
    {
        return $this->getBuilder()->build($this, $this->swapBytes($bytes));
    }

    /**
     * Swaps bytes according to the timestamp-first COMB rules
     */
    private function swapBytes($bytes)
    {
        $first48Bits = substr($bytes, 0, 6);
        $last48Bits = substr($bytes, -6);

        $bytes = substr_replace($bytes, $last48Bits, 0, 6);
        $bytes = substr_replace($bytes, $first48Bits, -6);

        return $bytes;
    }
}
