BitLy (bit.ly) is a service which allows users to shorten, expand, share and track URLs (links). bit.ly can be accessed through bit.ly website and a robust and open API.

Example:
Shorten http://www.if-not-true-then-false.com/ url -> http://bit.ly/8cZ1fb
Expand http://bit.ly/8cZ1fb url -> http://www.if-not-true-then-false.com/

This post deals with bit.ly API usage with a simple PHP Class. This PHP class allows to shorten normal urls, expand bit.ly urls and expand bit.ly hashes.

BitLy PHP Class⌗ 

<?php

class BitLy {
	private $break;
	private $api_version;
	private $format;
	private $login;
	private $apikey;

	// Constructor for BitLy class
	public function __construct($login, $apikey) {
		// Browser output then use "<br></br>"
		// Command line output use "\n" 
		$this->break = "\n";
		$this->api_version = "2.0.1";
		$this->format = "json";
		$this->login = $login;
		$this->apikey = $apikey;
	}

	// Shorten given url and returns shortened url
	public function shortenUrl($url) {
		$shortened_url = "";
		$encoded_url = urlencode($url);
		$bitly_url = "http://api.bit.ly/shorten?" . 
				"version=" . $this->api_version . 
				"&format=" . $this->format . 
				"&longUrl=" . $encoded_url . 
				"&login=" . $this->login . 
				"&apiKey=" . $this->apikey;

		$content = file_get_contents($bitly_url);
		
		try {
			$shortened_url = $this->parseContent($content, $url);
			
		}
		catch (Exception $e) {
			echo "Caught exception: " . 
				$e->getMessage() . $this->break;
			exit;
		}
		
		return $shortened_url;
	}

	// Expand given url and returns expanded url
	public function expandUrlByUrl($url) {
		$expanded_url = "";

		$hash = $this->parseBitlyUrl($url);

		$expanded_url = $this->expandUrlByHash($hash);

		return $expanded_url;
	}

	// Expand given hash and returns expanded url
	public function expandUrlByHash($hash) {
		$expanded_url = "";
		$bitly_url = "http://api.bit.ly/expand?" . 
				"version=" . $this->api_version . 
				"&format=" . $this->format . 
				"&hash=" . $hash . 
				"&login=" . $this->login . 
				"&apiKey=" . $this->apikey;

		$content = file_get_contents($bitly_url);

		try {
			$expanded_url = $this->parseContent($content, $hash);
		}
		catch (Exception $e) {
			echo "Caught exception: " . 
				$e->getMessage() . $this->break;
			exit;
		}

		return $expanded_url;
	}

	// Parse Bitly url returns bitly hash
	private function parseBitlyUrl($url) {
		$parsed_url = parse_url($url);
		return trim($parsed_url['path'], "/");
	}

	// Parse Content from Bitly API
	private function parseContent($content, $key) {
		// Decode json to array
		$content = json_decode($content, true);
		
		// Check errors
		if ($content['errorCode'] != 0 || 
		    $content['statusCode'] != "OK") {
			throw new Exception($content['statusCode'] . ": " . 
					$content['errorCode'] . " " . 
					$content['errorMessage']);
		}
		
		// Return right url or throw exception if not set
		if (isset($content['results'][$key]['longUrl'])) {
			return $content['results'][$key]['longUrl'];
		}
		else if (isset($content['results'][$key]['shortUrl'])) {
			return $content['results'][$key]['shortUrl'];
		}
		else {
			throw new Exception("ERROR. URL not found: " . $key);
		}
	}

}

BitLy PHP Class usage⌗ 

<?php

    require_once("BitLy.php");
	
    $bitly = new BitLy("bitlyapidemo", "R_0da49e0a9118ff35f52f629d2d71bf07");

    $url = "http://www.if-not-true-then-false.com/";
    $short_url = $bitly->shortenUrl($url);

    echo "Shorten " . $url . " url -> " . $short_url . "\n";

    echo "Expand " . $short_url . " url -> " . $bitly->expandUrlByUrl($short_url) . "\n";
    
    echo "Expand 8cZ1fb hash -> " . $bitly->expandUrlByHash("8cZ1fb") . "\n";

Output⌗ 

$ php test_bitly_class.php 
Shorten http://www.if-not-true-then-false.com/ url -> http://bit.ly/8cZ1fb
Expand http://bit.ly/8cZ1fb url -> http://www.if-not-true-then-false.com/
Expand 8cZ1fb hash -> http://www.if-not-true-then-false.com/