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<?php declare(strict_types=1); |
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/** |
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* ownCloud - Music app |
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* |
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* This file is licensed under the Affero General Public License version 3 or |
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* later. See the COPYING file. |
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* |
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* @author Pauli Järvinen <[email protected]> |
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* @copyright Pauli Järvinen 2020 |
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*/ |
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namespace OCA\Music\Utility; |
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use \OCA\Music\AppFramework\Core\Logger; |
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use \OCA\Music\Db\Cache; |
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class Random { |
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private $cache; |
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private $logger; |
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public function __construct(Cache $cache, Logger $logger) { |
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$this->cache = $cache; |
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$this->logger = $logger; |
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} |
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/** |
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* Create cryptographicaly secure random string |
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*/ |
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public static function secure(int $length) : string { |
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return \bin2hex(\random_bytes($length)); |
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} |
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/** |
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* Get desired number of random items from the given array |
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* |
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* @param array $itemArray |
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* @param int $count |
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* @return array |
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*/ |
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public static function pickItems(array $itemArray, int $count) : array { |
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$count = \min($count, \count($itemArray)); // can't return more than all items |
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if ($count == 0) { |
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return []; |
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} else { |
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$indices = \array_rand($itemArray, $count); |
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if ($count == 1) { // return type is not array when randomizing a single index |
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$indices = [$indices]; |
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} |
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\shuffle($indices); |
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return Util::arrayMultiGet($itemArray, $indices); |
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} |
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} |
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/** |
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* Get desired number of random array indices. This function supports paging |
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* so that all the indices can be browsed through page-by-page, without getting |
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* the same index more than once. This requires persistence and identifying the |
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* logical array in question. The array is identified by the user ID and a free |
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* text identifier supplied by the caller. |
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* |
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* For a single logical array, the indices are shuffled every time when the |
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* page 0 is requested. Also, if the size of the array in question has changed |
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* since the previous call, then the indices are reshuffled. |
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* |
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* @param int $arrSize |
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* @param int $offset |
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* @param int $count |
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* @param string $userId |
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* @param string $arrId |
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* @return int[] |
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*/ |
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public function getIndices(int $arrSize, int $offset, int $count, string $userId, string $arrId) : array { |
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$cacheKey = 'random_indices_' . $arrId; |
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$indices = self::decodeIndices($this->cache->get($userId, $cacheKey)); |
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// reshuffle if necessary |
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if ($offset == 0 || \count($indices) != $arrSize) { |
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if ($arrSize > 0) { |
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$indices = \range(0, $arrSize - 1); |
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} else { |
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$indices = []; |
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} |
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\shuffle($indices); |
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$this->cache->set($userId, $cacheKey, self::encodeIndices($indices)); |
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} |
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return \array_slice($indices, $offset, $count); |
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} |
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private static function encodeIndices($indices) { |
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return \implode(',', $indices); |
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} |
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private static function decodeIndices($buffer) { |
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if (empty($buffer)) { |
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return []; |
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} else { |
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return \explode(',', $buffer); |
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} |
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} |
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} |
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owncloud /
music
