streams/Zotlabs/Lib/Img_cache.php

<?php
namespace Zotlabs\Lib;
 

class Img_cache {

	static $cache_life = 18600 * 7;

	static function get_filename($url, $prefix = EMPTY_STR) {
		$hash = hash('sha256', $url);
		$slug = substr($hash,0,2);
		$path = $prefix . '/' . $slug;
		os_mkdir($path, STORAGE_DEFAULT_PERMISSIONS, true);
		return $path . '/' . $hash;
	}

	static function check($url, $prefix = EMPTY_STR) {

		if (strpos($url,z_root()) !== false) {
			return false;
		}
		
		$path = self::get_filename($url,$prefix);
		if (file_exists($path)) {
			$t = filemtime($path);
			if ($t && time() - $t >= self::$cache_life) {
				if (self::url_to_cache($url,$path)) {
					return true;
				}
				return false;
			}
			return true;
		}

		return self::url_to_cache($url,$path);
	}


	static function url_to_cache($url,$file) {

		$fp = fopen($file,'wb');

		if (! $fp) {
			logger('failed to open storage file: ' . $file,LOGGER_NORMAL,LOG_ERR);
			return false;
		}
		
		$redirects = 0;
		$x = z_fetch_url($url,true,$redirects,[ 'filep' => $fp, 'novalidate' => true ]);

		fclose($fp);
		if ($x['success']) {
			return true;
		}
		unlink($file); 
		return false;
	}

}