Added comments

url-shortener.php

@@ -17,8 +17,16 @@ public function __construct(&$db = false, $table = false)
 		require_once('config.php');
 		$this->config = $config;
 
+		/**
+		 * If no PDO object is sent, create one. It is preferred that if you
+		 * already have a PDO object it should be sent. It will be used as
+		 * a reference and will not be changed, but will speed up the
+		 * construction of the shortener class as it won't have to create a
+		 * new connection to the database.
+		 */
 		if ($db)
 		{
+			//$db can only be PDO, here we check for that
 			if (!is_a($db, 'PDO'))
 			{
 				trigger_error('Must be PDO', E_USER_ERROR);
@@ -31,6 +39,11 @@ public function __construct(&$db = false, $table = false)
 			$this->db = new PDO($dsn, $this->config['user'], $this->config['pass']);
 		}
 
+		/**
+		 * Generate a prepared statement, so that if the get method is
+		 * called more than one, the prepared statement is only called
+		 * once, making the script faster.
+		 */
 		$this->prepared = $this->db->prepare('SELECT url FROM ' . $this->config['table'] . ' WHERE s_key = ?');
 
 		if ($table)
@@ -39,11 +52,20 @@ public function __construct(&$db = false, $table = false)
 		}
 	}
 
+	/**
+	 * Gets one or more values from the database. If $key is a number, it
+	 * will get that many values and order them by $type, but if $key is the
+	 * key, it will return the corresponding URL
+	 *
+	 * @param mixed $key The key to search for / the amount of rows to
+	 * 	return
+	 * @param string $type If $key is an int, order  by this
+	 */
 	public function get($key, $type = false)
 	{
 		if (is_int($key) && $type)
 		{
-			if (preg_match('/author:(?<author>.*)/', $type, $matches))
+			if (preg_match('/(/<searchfor>.*):(?<author>.*)/', $type, $matches))
 			{
 				/**
 				 * @todo Add this!
@@ -58,17 +80,45 @@ public function get($key, $type = false)
 		}
 		else
 		{
+			//get single entry
 			$statement = $this->prepared;
 			$statement->execute(array($key));
 			$statement = $statement->fetchObject();
 			return $statement->url;
 		}
 	}
 
+	/**
+	 * Submit a URL into the database. Will return the key.
+	 *
+	 * @param string $url The URL to insert
+	 */
 	public function submit($url)
 	{
 		/**
-		 * @todo Validate URL
+		 * Primative regex check
+		 */
+		if (!preg_match('/^(?<proto>https?:\/{2})(?<domain>[a-zA-Z0-9\-.]+\.[a-zA-Z]{2,3})(?<path>\/\S*)?$/', $url, $matches))
+		{
+			$this->error = 'Invalid domain';
+			return false;
+		}
+
+		/**
+		 * Checking for an MX record will slow down the script. If you are
+		 * finding the script too slow, disable this option using the 'mx'
+		 * option in the configuration
+		 */
+		if ($config['mx'] && !checkdnsrr($matches['domain'], 'MX'))
+		{
+			$this->error = 'No MX record found for domain';
+			return false;
+		}
+
+		/**
+		 * If allowed, check whether the URL is already in the database. If
+		 * it is, then just return the key for the old one as there is no
+		 * point in creating a new one.
 		 */
 		if (!$this->config['unique'])
 		{
@@ -89,11 +139,14 @@ public function submit($url)
 		$key = substr(md5(uniqid(rand(), true)), 0, $this->config['length']);
 		$statement->execute(array($key));
 
+		//check whether the key exists. If it does, make a new one.
 		while ($statement->rowCount() > 0)
 		{
 			$key = substr(md5(uniqid(rand(), true)), 0, $this->config['length']);
 			$statement->execute(array($key));
 		}
+
+		//insert into database
 		$statement = $this->db->prepare('INSERT INTO ' . $this->config['table'] . ' (s_key, url) VALUES (?, ?)');
 		$statement->execute(array($key, $url));
 		return $key;