A simple GW2 chatlink class with support for IDs > 16 bit

chatlink.class.php

<?php

/**
 * Simple GW2 chatlink class with support for IDs > 16 bit
 *
 * @author     Smiley <@codemasher>
 * @license    http://www.wtfpl.net/about/ WTFPL 2
 */
class Chatlink{
	/**
	 * @var array
	 *
	 * @link http://wiki.guildwars2.com/wiki/Chat_link_format
	 */
	private $chatlink_types = [
		'coin'   => 1,
		'item'   => 2,
		'text'   => 3,
		'map'    => 4,
		'skill'  => 7,
		'trait'  => 8,
		'recipe' => 10,
		'skin'   => 11,
		'outfit' => 12
	];

	/**
	 * @param int $type_id
	 * @param int $id
	 *
	 * @return string
	 *
	 * @author poke <@poke>
	 * @author Smiley <@codemasher>
	 *
	 * @link   http://wiki.guildwars2.com/wiki/Widget:Game_link
	 */
	public function encode($type_id, $id){
		$data = [];
		while($id > 0){
			$data[] = $id & 255;
			$id = $id >> 8;
		}

		while(count($data) < 4 || count($data) % 2 !== 0){
			$data[] = 0;
		}

		// add quantity if we are encoding an item
		if($type_id === 2){
			array_unshift($data, 1);
		}
		array_unshift($data, $type_id);

		// encode data
		$chatlink = '';
		for($i = 0; $i < count($data); $i++){
			$chatlink .= chr($data[$i]);
		}

		return '[&'.base64_encode($chatlink).']';
	}

	/**
	 * @param string $chatlink
	 *
	 * @return array|bool
	 *
	 * @author poke <@poke>
	 * @author Smiley <@codemasher>
	 *
	 * @link   http://ideone.com/0RSpAA
	 */
	public function decode($chatlink){
		if(preg_match('/\[&([a-z\d+\/]+=*)\]/i', $chatlink)){
			$data = [];

			// decode base64 and read octets
			foreach(str_split(base64_decode($chatlink)) as $char){
				$data[] = ord($char);
			}

			if(!in_array($data[0], $this->chatlink_types)){
				// invalid type
				return false;
			}

			// items have the quantity first, so set an offset
			$o = $data[0] === 2 ? 1 : 0;

			// get id
			$id = $data[3 + $o] << 16 | $data[2 + $o] << 8 | $data[1 + $o];

			// [id, type]
			return [$id, $data[0]];
		}

		// invalid chatlink
		return false;
	}

}