<?php

/**
 * This file is part of CodeIgniter 4 framework.
 *
 * (c) CodeIgniter Foundation <admin@codeigniter.com>
 *
 * For the full copyright and license information, please view
 * the LICENSE file that was distributed with this source code.
 */

namespace CodeIgniter\Cache\Handlers;

use Closure;
use CodeIgniter\Cache\CacheInterface;
use Exception;
use InvalidArgumentException;

/**
 * Base class for cache handling
 */
abstract class BaseHandler implements CacheInterface
{
    /**
     * Reserved characters that cannot be used in a key or tag.
     * From https://github.com/symfony/cache-contracts/blob/c0446463729b89dd4fa62e9aeecc80287323615d/ItemInterface.php#L43
     */
    public const RESERVED_CHARACTERS = '{}()/\@:';

    /**
     * Maximum key length.
     */
    public const MAX_KEY_LENGTH = PHP_INT_MAX;

    /**
     * Prefix to apply to cache keys.
     * May not be used by all handlers.
     *
     * @var string
     */
    protected $prefix;

    /**
     * Validates a cache key according to PSR-6.
     * Keys that exceed MAX_KEY_LENGTH are hashed.
     * From https://github.com/symfony/cache/blob/7b024c6726af21fd4984ac8d1eae2b9f3d90de88/CacheItem.php#L158
     *
     * @param string $key    The key to validate
     * @param string $prefix Optional prefix to include in length calculations
     *
     * @throws InvalidArgumentException When $key is not valid
     */
    public static function validateKey($key, $prefix = ''): string
    {
        if (! is_string($key)) {
            throw new InvalidArgumentException('Cache key must be a string');
        }
        if ($key === '') {
            throw new InvalidArgumentException('Cache key cannot be empty.');
        }
        if (strpbrk($key, self::RESERVED_CHARACTERS) !== false) {
            throw new InvalidArgumentException('Cache key contains reserved characters ' . self::RESERVED_CHARACTERS);
        }

        // If the key with prefix exceeds the length then return the hashed version
        return strlen($prefix . $key) > static::MAX_KEY_LENGTH ? $prefix . md5($key) : $prefix . $key;
    }

    /**
     * Get an item from the cache, or execute the given Closure and store the result.
     *
     * @param string  $key      Cache item name
     * @param int     $ttl      Time to live
     * @param Closure $callback Callback return value
     *
     * @return mixed
     */
    public function remember(string $key, int $ttl, Closure $callback)
    {
        $value = $this->get($key);

        if ($value !== null) {
            return $value;
        }

        $this->save($key, $value = $callback(), $ttl);

        return $value;
    }

    /**
     * Deletes items from the cache store matching a given pattern.
     *
     * @param string $pattern Cache items glob-style pattern
     *
     * @throws Exception
     */
    public function deleteMatching(string $pattern)
    {
        throw new Exception('The deleteMatching method is not implemented.');
    }
}