<?php

menu_register(array(
        'oauth' => array(
                'callback' => 'user_oauth',
                'hidden' => 'true',
        ),
        'login' => array(
                'callback' => 'user_login',
                'hidden' => 'true',
        ),
));

function user_oauth() {
        require_once 'OAuth.php';

        // Session used to keep track of secret token during authorisation step
        session_start();

        // Flag forces twitter_process() to use OAuth signing
        $GLOBALS['user']['type'] = 'oauth';

        if ($oauth_token = $_GET['oauth_token']) {
                // Generate ACCESS token request
                $params = array('oauth_verifier' => $_GET['oauth_verifier']);
                $response = twitter_process('https://api.twitter.com/oauth/access_token', $params);
                parse_str($response, $token);

                // Store ACCESS tokens in COOKIE
                $GLOBALS['user']['password'] = $token['oauth_token'] .'|'.$token['oauth_token_secret'];

                // Fetch the user's screen name with a quick API call
                unset($_SESSION['oauth_request_token_secret']);
                $user = twitter_process('https://api.twitter.com/1.1/account/verify_credentials.json');
                $GLOBALS['user']['username'] = $user->screen_name;

                _user_save_cookie(1);
                header('Location: '. BASE_URL);
                exit();

        } else {
                // Generate AUTH token request
                $params = array('oauth_callback' => BASE_URL.'oauth');
                $response = twitter_process('https://api.twitter.com/oauth/request_token', $params);
                parse_str($response, $token);

                // Save secret token to session to validate the result that comes back from Twitter
                $_SESSION['oauth_request_token_secret'] = $token['oauth_token_secret'];

                // redirect user to authorisation URL
                $authorise_url = 'https://api.twitter.com/oauth/authorize?oauth_token='.$token['oauth_token'];
                header("Location: $authorise_url");
        }
}

function user_oauth_sign(&$url, &$args = false) {
        require_once 'OAuth.php';

        $method = $args !== false ? 'POST' : 'GET';

        // Move GET parameters out of $url and into $args
        if (preg_match_all('#[?&]([^=]+)=([^&]+)#', $url, $matches, PREG_SET_ORDER)) {
                foreach ($matches as $match) {
                        $args[$match[1]] = $match[2];
                }
                $url = substr($url, 0, strpos($url, '?'));
        }

        $sig_method = new OAuthSignatureMethod_HMAC_SHA1();
        $consumer = new OAuthConsumer(OAUTH_CONSUMER_KEY, OAUTH_CONSUMER_SECRET);
        $token = NULL;

        if (($oauth_token = $_GET['oauth_token']) && $_SESSION['oauth_request_token_secret']) {
                $oauth_token_secret = $_SESSION['oauth_request_token_secret'];
        } else {
                list($oauth_token, $oauth_token_secret) = explode('|', $GLOBALS['user']['password']);
        }
        if ($oauth_token && $oauth_token_secret) {
                $token = new OAuthConsumer($oauth_token, $oauth_token_secret);
        }

        $request = OAuthRequest::from_consumer_and_token($consumer, $token, $method, $url, $args);
        $request->sign_request($sig_method, $consumer, $token);

        switch ($method) {
                case 'GET':
                        $url = $request->to_url();
                        $args = false;
                        return;
                case 'POST':
                        $url = $request->get_normalized_http_url();
                        $args = $request->to_postdata();
                        return;
        }
}

function user_ensure_authenticated() {
        if (!user_is_authenticated()) {
                $content = theme('login');
                $content .= file_get_contents('about.html');
                theme('page', 'Login', $content);
        }
}

function user_logout() {
        unset($GLOBALS['user']);
        setcookie('USER_AUTH', '', time() - 3600, '/');
}

function user_is_authenticated() {
        if (!isset($GLOBALS['user'])) {
                if(array_key_exists('USER_AUTH', $_COOKIE)) {
                        _user_decrypt_cookie($_COOKIE['USER_AUTH']);
                } else {
                        $GLOBALS['user'] = array();
                }
        }
      
        // Auto-logout any users that aren't correctly using OAuth
        if (user_current_username() && user_type() !== 'oauth') {
                user_logout();
                twitter_refresh('logout');
        }

        if (!user_current_username()) {
                if ($_POST['username'] && $_POST['password']) {
                        $GLOBALS['user']['username'] = trim($_POST['username']);
                        $GLOBALS['user']['password'] = $_POST['password'];
                        $GLOBALS['user']['type'] = 'oauth';
                      
                        $sql = sprintf("SELECT * FROM user WHERE username='%s' AND password=MD5('%s') LIMIT 1", mysql_escape_string($GLOBALS['user']['username']), mysql_escape_string($GLOBALS['user']['password']));
                        $rs = mysql_query($sql);
                        if ($rs && $user = mysql_fetch_object($rs)) {
                                $GLOBALS['user']['password'] = $user->oauth_key . '|' . $user->oauth_secret;
                        } else {
                                theme('error', 'Invalid username or password.');
                        }
                      
                        _user_save_cookie($_POST['stay-logged-in'] == 'yes');
                        header('Location: '. BASE_URL);
                        exit();
                } else {
                        return false;
                }
        }
        return true;
}

function user_current_username() {
        return $GLOBALS['user']['username'];
}

function user_is_current_user($username) {
        return (strcasecmp($username, user_current_username()) == 0);
}

function user_type() {
        return $GLOBALS['user']['type'];
}

function _user_save_cookie($stay_logged_in = 0) {
        $cookie = _user_encrypt_cookie();
        $duration = 0;
        if ($stay_logged_in) {
                $duration = time() + (3600 * 24 * 365);
        }
        setcookie('USER_AUTH', $cookie, $duration, '/');
}

function _user_encryption_key() {
        return ENCRYPTION_KEY;
}

function _user_encrypt_cookie() {
        $plain_text = $GLOBALS['user']['username'] . ':' . $GLOBALS['user']['password'] . ':' . $GLOBALS['user']['type'];

        $td = mcrypt_module_open('blowfish', '', 'cfb', '');
        $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
        mcrypt_generic_init($td, _user_encryption_key(), $iv);
        $crypt_text = mcrypt_generic($td, $plain_text);
        mcrypt_generic_deinit($td);
        return base64_encode($iv.$crypt_text);
}

function _user_decrypt_cookie($crypt_text) {
        $crypt_text = base64_decode($crypt_text);
        $td = mcrypt_module_open('blowfish', '', 'cfb', '');
        $ivsize = mcrypt_enc_get_iv_size($td);
        $iv = substr($crypt_text, 0, $ivsize);
        $crypt_text = substr($crypt_text, $ivsize);
        mcrypt_generic_init($td, _user_encryption_key(), $iv);
        $plain_text = mdecrypt_generic($td, $crypt_text);
        mcrypt_generic_deinit($td);

        list($GLOBALS['user']['username'], $GLOBALS['user']['password'], $GLOBALS['user']['type']) = explode(':', $plain_text);
}

function user_login() {
        return theme('page', 'Login','
<form method="post" action="'.$_GET['q'].'">
<p>Username <input name="username" size="15" />
<br />Password <input name="password" type="password" size="15" />
<br /><label><input type="checkbox" checked="checked" value="yes" name="stay-logged-in" /> Stay logged in? </label>
<br /><input type="submit" value="Sign In" /></p>
</form>

<p><b>Registration steps:</b></p>

<ol>
        <li><a href="oauth">Sign in via Twitter.com</a> from any computer</li>
        <li>Visit the Dabr settings page to choose a password</li>
        <li>Done! You can now benefit from accessing Twitter through Dabr from anywhere (even from computers that block Twitter.com)</li>
</ol>
');
}

function theme_login() {
        $content = '<div style="margin:1em; font-size: 1.2em">
<p><a href="oauth"><img src="images/twitter_button_2_lo.gif" alt="Sign in with Twitter/OAuth" width="165" height="28" /></a><br /><a href="oauth">Sign in via Twitter.com</a></p>
<p>Twitter no longer allow you to log in directly with a username and password so we can\'t show the standard login form. There\'s some more information on the <a href="http://blog.dabr.co.uk/">Dabr blog</a>.</p>';
      
        if (MYSQL_USERS == 'ON') $content .= '<p>No access to Twitter.com? <a href="login">Sign in with your Dabr account</a></p>';
        $content .= '</div>';
        return $content;
}

function theme_logged_out() {
        return '<p>Logged out. <a href="">Login again</a></p>';
}