<?php

	session_start();

	session_register('is_logged_in');
	session_register('logged_in_as');

	$username = $_POST['username'];
	$password = $_POST['password'];

	$Salt = uniqid();
	$Algo = '6';
	$Rounds = '7500';
	$cryptSalt = '$' . $Algo . '$rounds=' . $Rounds . '$' . $Salt;

	$finalPassword = crypt($password, $cryptSalt);

	function authenticate() {

		try {
			$db = new PDO('mysql:host=localhost;dbname=db;charset=UTF-8', 'root', 'password', array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
		} catch(PDOException $ex) {
			echo "An error occured: " . $ex;
		}

		$prepquery = $db->prepare('SELECT * FROM users WHERE :password = password AND username = :username');
		$prepquery->bindParam(':username', $username);
		$prepquery->bindParam(':password', $finalPassword);
		$prepquery->execute();
		$res = $prepquery->fetch(PDO::FETCH_ASSOC);

		return !empty($res) ?  true : false;
	}

	if(authenticate()) {
		echo "You are now logged in as " . $username . ".";
		$_SESSION['is_logged_in'] = 1;
		$_SESSION['logged_in_as'] = $username;
	} else if($_SESSION['is_logged_in'] === 1) {
			echo "You are already logged in!";
	} else {
		echo "The username or password was incorrect. <br /> " . $finalPassword;
	}