SWDB/application/helper/APPLICATION_Helper.php

<?php
    /**
     * App helper file.
     *
     * Provides a helper to perform app related operations.
     *
     * @category Helper.
     */

    /**
     * Require dependent files if not present.
     */
    require_once(PATH::HELPER . "Helper.php");

    /**
     * Application helper.
     *
     * Contains app-related utilities.
     *
     * @category Helper.
     */
    final class APPLICATION extends Helper{

        /**
         * Checks if a value is a valid one in a constant class.
         *
         * It will intentionally fail when used for a non constant class.
         *
         * @param string $class Name of the class.
         * @param int $value Value to check.
         * @return bool True if the value is defined, false otherwise.
         */
        public static function valid_id($class, $value){
            if (strtoupper($class) != $class){
                return false;
            }
            if (!class_exists($class, false)){
                return false;
            }
            $reflect = new ReflectionClass($class);
            if (in_array($value, $reflect->getConstants())){
                return true;
            }
            else{
                return false;
            }
        }

        /**
         * Forms an image URL.
         *
         * It will intentionally fail when used for a non constant class.
         *
         * @param string $type Image type. valid values are:
         *   ICON,    LOGO,         CURRENCY,    UNIT,
         *   AREA,    SKILL,        ESSENCE,     RUNE,
         *   GRIND,   ELEMENT,      SKILL_GUILD, DECORATION,
         *   SOURCE,  SKILL_LEADER, INVENTORY,   EFFECT,
         *   BUILDING
         * @param string|int $name Filename, with no path or extension. It can also
         * skip the padding. An id can be used.
         * @return Image URL if found. If not, the URL to an 'unknown' icon.
         */
        public static function img($type, $name){
            $pad = 1;
            $url = URL::IMG["UNKNOWN"];
            while ($pad < 10){
                if (isset(PATH::IMG[$type]) && file_exists(PATH::IMG[$type] . str_pad($name, $pad, '0', STR_PAD_LEFT) . ".png")){
                    $url = URL::IMG[$type] . str_pad($name, $pad, '0', STR_PAD_LEFT) . ".png";
                    break;
                }
                $pad ++;
            }
            return $url;
        }
    }
?>