<?php declare(strict_types=1);
/**
 * Banker
 *
 * A Caching library implementing psr/cache (PSR 6) and psr/simple-cache (PSR 16)
 *
 * PHP version 7.4
 *
 * @package     Banker
 * @author      Timothy J. Warren <tim@timshomepage.net>
 * @copyright   2016 - 2020  Timothy J. Warren
 * @license     http://www.opensource.org/licenses/mit-license.html  MIT License
 * @version     3.0.0
 * @link        https://git.timshomepage.net/timw4mail/banker
 */
namespace Aviat\Banker;

use Aviat\Banker\Exception\InvalidArgumentException;
use Psr\SimpleCache;
use Psr\Log\LoggerInterface;

class Teller implements SimpleCache\CacheInterface {
	private Pool $pool;

	/**
	 * Set up the cache backend
	 *
	 * @param array $config
	 * @param LoggerInterface $logger
	 */
	public function __construct(array $config, ?LoggerInterface $logger = NULL)
	{
		$this->pool = new Pool($config, $logger);
	}

	/**
	 * Fetches a value from the cache.
	 *
	 * @param string $key     The unique key of this item in the cache.
	 * @param mixed  $default Default value to return if the key does not exist.
	 *
	 * @return mixed The value of the item from the cache, or $default in case of cache miss.
	 *
	 * @throws SimpleCache\InvalidArgumentException
	 *   MUST be thrown if the $key string is not a legal value.
	 */
	public function get($key, $default = null)
	{
		$this->validateKey($key);

		$item = $this->pool->getItem($key);
		return ($item->isHit()) ? $item->get() : $default;
	}

	/**
	 * Persists data in the cache, uniquely referenced by a key with an optional expiration TTL time.
	 *
	 * @param string                 $key   The key of the item to store.
	 * @param mixed                  $value The value of the item to store, must be serializable.
	 * @param null|int|\DateInterval $ttl   Optional. The TTL value of this item. If no value is sent and
	 *                                      the driver supports TTL then the library may set a default value
	 *                                      for it or let the driver take care of that.
	 *
	 * @return bool True on success and false on failure.
	 *
	 * @throws SimpleCache\InvalidArgumentException
	 *   MUST be thrown if the $key string is not a legal value.
	 */
	public function set($key, $value, $ttl = null): bool
	{
		$this->validateKey($key);

		$item = $this->pool->getItem($key);
		$item->set($value);

		if ($ttl !== NULL)
		{
			$item->expiresAfter($ttl);
		}

		return $this->pool->save($item);
	}

	/**
	 * Delete an item from the cache by its unique key.
	 *
	 * @param string $key The unique cache key of the item to delete.
	 *
	 * @return bool True if the item was successfully removed. False if there was an error.
	 *
	 * @throws SimpleCache\InvalidArgumentException
	 *   MUST be thrown if the $key string is not a legal value.
	 */
	public function delete($key): bool
	{
		$this->validateKey($key);

		return $this->pool->deleteItem($key);
	}

	/**
	 * Wipes clean the entire cache's keys.
	 *
	 * @return bool True on success and false on failure.
	 */
	public function clear(): bool
	{
		return $this->pool->clear();
	}

	/**
	 * Obtains multiple cache items by their unique keys.
	 *
	 * @param iterable $keys    A list of keys that can obtained in a single operation.
	 * @param mixed    $default Default value to return for keys that do not exist.
	 *
	 * @return iterable A list of key => value pairs. Cache keys that do not exist or are stale will have $default as value.
	 *
	 * @throws SimpleCache\InvalidArgumentException
	 *   MUST be thrown if $keys is neither an array nor a Traversable,
	 *   or if any of the $keys are not a legal value.
	 */
	public function getMultiple($keys, $default = null)
	{
		$this->validateKeys($keys);

		$output = [];

		foreach ($keys as $k)
		{
			$output[$k] = $this->get($k, $default);
		}

		return $output;
	}

	/**
	 * Persists a set of key => value pairs in the cache, with an optional TTL.
	 *
	 * @param iterable               $values A list of key => value pairs for a multiple-set operation.
	 * @param null|int|\DateInterval $ttl    Optional. The TTL value of this item. If no value is sent and
	 *                                       the driver supports TTL then the library may set a default value
	 *                                       for it or let the driver take care of that.
	 *
	 * @return bool True on success and false on failure.
	 *
	 * @throws SimpleCache\InvalidArgumentException
	 *   MUST be thrown if $values is neither an array nor a Traversable,
	 *   or if any of the $values are not a legal value.
	 */
	public function setMultiple($values, $ttl = null): bool
	{
		$this->validateKeys($values, TRUE);

		$setResults = [];
		foreach ($values as $k => $v)
		{
			$setResults[] = $this->set($k, $v, $ttl);
		}

		// Only return true if all the results are true
		return array_reduce($setResults, fn ($carry, $item) => $item && $carry, TRUE);
	}

	/**
	 * Deletes multiple cache items in a single operation.
	 *
	 * @param iterable $keys A list of string-based keys to be deleted.
	 *
	 * @return bool True if the items were successfully removed. False if there was an error.
	 *
	 * @throws SimpleCache\InvalidArgumentException
	 *   MUST be thrown if $keys is neither an array nor a Traversable,
	 *   or if any of the $keys are not a legal value.
	 */
	public function deleteMultiple($keys): bool
	{
		$this->validateKeys($keys);

		return $this->pool->deleteItems((array)$keys);
	}

	/**
	 * Determines whether an item is present in the cache.
	 *
	 * NOTE: It is recommended that has() is only to be used for cache warming type purposes
	 * and not to be used within your live applications operations for get/set, as this method
	 * is subject to a race condition where your has() will return true and immediately after,
	 * another script can remove it making the state of your app out of date.
	 *
	 * @param string $key The cache item key.
	 *
	 * @return bool
	 *
	 * @throws SimpleCache\InvalidArgumentException
	 *   MUST be thrown if the $key string is not a legal value.
	 */
	public function has($key): bool
	{
		$this->validateKey($key);

		return $this->pool->hasItem($key);
	}

	/**
	 * @param $keys
	 * @param bool $hash
	 * @throws InvalidArgumentException
	 */
	private function validateKeys($keys, bool $hash = FALSE): void
	{
		// Check type of keys
		if ( ! is_iterable($keys))
		{
			throw new InvalidArgumentException('Keys must be an array or a traversable object');
		}

		$keys = ($hash) ? array_keys((array)$keys) : (array)$keys;

		// Check each key
		array_walk($keys, fn($key) => $this->validateKey($key));
	}

	/**
	 * @param string $key
	 * @throws InvalidArgumentException
	 */
	private function validateKey($key): void
	{
		if ( ! is_string($key))
		{
			throw new InvalidArgumentException('Cache key must be a string.');
		}

		if (is_string($key) && preg_match("`[{}()/@:\\\]`", $key) === 1)
		{
			throw new InvalidArgumentException('Invalid characters in cache key');
		}
	}
}