class.instagram.php

<?php

/**
 * Class Instagram
 * A simple class that connects to the Instagram API without the overhead
 * of other classes. This class depends on cURL being installed on your OS
 * and it MUST be enabled in PHP. If you're not sure if it's enabled, you can
 * run phpinfo() and search for cURL.
 * @author Dennis Thompson
 * @license MIT
 * @version 1.0
 * @copyright AtomicPages LLC 2014
 */
class Instagram {

	private $displaySize, $accessToken, $count, $id, $cache;

	public function __construct($id, $token, $cache = true) {
		$this->id = $id;
		$this->accessToken = $token;
		$this->count = 10;
		$this->cache = $cache;
	}

	public function size($size) {
		$this->displaySize = $size;
	}

	public function cache($bool) {
		$this->cache = $bool;
	}

	public function token($token) {
		$this->accessToken = $token;
	}

	public function count($count) {
		$this->count = $count;
	}

	public function getCache() {
		return $this->cache;
	}

	public function getCount() {
		return $this->count;
	}

	public function getSize() {
		return $this->displaySize;
	}

	/**
	 * Returns the access token. We don't want this method public!
	 * @return string
	 * @access protected
	 */
	protected function getAccessToken() {
		return $this->accessToken;
	}

	/**
	 * Returns the ID of the user's instagram feed.
	 * @return string
	 * @access protected
	 */
	protected function getID() {
		return $this->id;
	}

	/**
	 * Pulls information from the Instagram API and returns it as a hashtable
	 * @return array | NULL on failure
	 * @throws InvalidArgumentException
	 * @access public
	 */
	public function fetch() {
		if(!isset($this->id)) {
			throw new InvalidArgumentException("ID cannot be empty!", 1);
		}

		if(!isset($this->accessToken)) {
			throw new InvalidArgumentException("Access Token cannot be empty!", 1);
		}

		if(!function_exists("curl_init")) {
			throw new BadFunctionCallException("cURL is not enabled on this host! It must be enabled for this script
			to work!", 1);
		}

		$url = "https://api.instagram.com/v1/users/" . $this->id . "/media/recent/?access_token=" . $this->accessToken;

		$ch = curl_init();
		curl_setopt($ch, CURLOPT_URL, $url);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
		curl_setopt($ch, CURLOPT_TIMEOUT, 20);
		$result = curl_exec($ch);
		curl_close($ch);
		$result = json_decode($result);
		if($this->cache) {
			// TODO: need to handle this exception with something so we know when it happens. Maybe use try-catch?
			$this->writeCache($result);
		}

		return $result;
	}

	/**
	 * A method that writes custom JSON data directly to a file.
	 * The file serves as local cache to reduce the number of calls
	 * to the Instagram API and takes the load off the server when high
	 * volumes of users are on the site. Returns false on failure.
	 * @param $array
	 * @return bool
	 * @see buildJsonString for JSON format
	 */
	// TODO: Maybe can the return value and throw exceptions instead?
	private function writeCache($array) {
		if(!is_object($array)) {
			throw new InvalidArgumentException("Parameter must be an array!", 1);
		}

		$filename = $_SERVER["DOCUMENT_ROOT"] . "/insta_cache.json";
		if(!file_exists($filename) || (filemtime($filename) > (time() - 60 * 60 * 2 ))) { // cache is > 2 hours old
			$fp = fopen($filename, "w");
			if($fp != NULL) {
				$json = $this->buildJsonString($array);
				if(flock($fp, LOCK_EX)) { // acquire exclusive lock
					if(!ftruncate($fp, 0)) { // truncate the file
						rewind($fp); // rewind the stream just in case...
					}
					fwrite($fp, $json);
					flock($fp, LOCK_UN); // release the lock
				}
				fclose($fp);
			}
		}
	}

	/**
	 * A method that formats and converts $array into a JSON string
	 * that is handed off to Instagram::writeCache()
	 * @param $array
	 * @return string
	 * @see writeCache
	 */
	private function buildJsonString($array) {
		if(!is_object($array)) {
			throw new InvalidArgumentException("Parameter must be an array!", 1);
		}

		if(count($array->data) < $this->getCount()) {
			$this->count(count($array->data));
		}

		$json = "{\n\t\"images\": [\n";
		$separator = ",";
		for($i = 0; $i < $this->getCount(); $i++) {
			if($i == $this->getCount() - 1) {
				$separator = "";
			}
			$json .= json_encode($array->data[$i]->images) . $separator;
		}
		$json .= "\n\t]\n}";
		unset($separator); // deallocate memory for $separator

		return $json;
	}

}