/**
 * Pick the right DB class and return an instance
 *
 * @since 1.7
 * @param string $extension Optional: user defined choice
 * @return class $ydb DB class instance
 */
function yourls_set_DB_driver()
{
    // Auto-pick the driver. Priority: user defined, then PDO, then mysqli, then mysql
    if (defined('YOURLS_DB_DRIVER')) {
        $driver = strtolower(YOURLS_DB_DRIVER);
        // accept 'MySQL', 'mySQL', etc
    } elseif (extension_loaded('pdo_mysql')) {
        $driver = 'pdo';
    } elseif (extension_loaded('mysqli')) {
        $driver = 'mysqli';
    } elseif (extension_loaded('mysql')) {
        $driver = 'mysql';
    } else {
        $driver = '';
    }
    // Set the new driver
    if (in_array($driver, array('mysql', 'mysqli', 'pdo'))) {
        require_once YOURLS_INC . '/ezSQL/ez_sql_core.php';
        require_once YOURLS_INC . '/ezSQL/ez_sql_core_yourls.php';
        require_once YOURLS_INC . '/ezSQL/ez_sql_' . $driver . '.php';
        require_once YOURLS_INC . '/ezSQL/ez_sql_' . $driver . '_yourls.php';
    }
    $class = 'ezSQL_' . $driver . '_yourls';
    global $ydb;
    if (!class_exists($class, false)) {
        $ydb = new stdClass();
        yourls_die(yourls__('YOURLS requires the mysql, mysqli or pdo_mysql PHP extension. No extension found. Check your server config, or contact your host.'), yourls__('Fatal error'), 503);
    }
    yourls_do_action('set_DB_driver', $driver);
    $ydb = new $class(YOURLS_DB_USER, YOURLS_DB_PASS, YOURLS_DB_NAME, YOURLS_DB_HOST);
    yourls_debug_log("DB driver: {$driver}");
}

/**
 * Check if server has MySQL 5.0+
 *
 */
function yourls_check_database_version()
{
    global $ydb;
    // Attempt to get MySQL server version, check result and if error count increased
    $num_errors1 = count($ydb->captured_errors);
    $version = yourls_get_database_version();
    $num_errors2 = count($ydb->captured_errors);
    if ($version == NULL || $num_errors2 > $num_errors1) {
        yourls_die(yourls__('Incorrect DB config, or could not connect to DB'), yourls__('Fatal error'), 503);
    }
    return version_compare('5.0', $version) <= 0;
}

function ozh_yourls_antispam_check_redirect($url, $keyword = false)
{
    if (is_array($url) && $keyword == false) {
        $keyword = $url[1];
        $url = $url[0];
    }
    // Check when the link was added
    // If shorturl is fresh (ie probably clicked more often?) check once every 15 times, otherwise once every 5 times
    // Define fresh = 3 days = 259200 secondes
    // TODO: when there's a shorturl_meta table, store last check date to allow checking every 2 or 3 days
    $now = date('U');
    $then = date('U', strtotime(yourls_get_keyword_timestamp($keyword)));
    $chances = $now - $then > 259200 ? 15 : 5;
    if ($chances == mt_rand(1, $chances)) {
        if (ozh_yourls_antispam_is_blacklisted($url) != false) {
            // Delete link & die
            yourls_delete_link_by_keyword($keyword);
            yourls_die('This domain has been blacklisted. This short URL has been deleted from our record.', 'Domain blacklisted', '403');
        }
    }
    // Nothing, move along
}

// This file initialize everything needed for YOURLS
// Include settings
if (file_exists(dirname(__FILE__) . '/config.php')) {
    // config.php in /includes/
    require_once dirname(__FILE__) . '/config.php';
} elseif (file_exists(dirname(dirname(__FILE__)) . '/user/config.php')) {
    // config.php in /user/
    require_once dirname(dirname(__FILE__)) . '/user/config.php';
} else {
    // config.php not found :(
    die('<p class="error">Cannot find <tt>config.php</tt>.</p><p>Please read the <tt>readme.html</tt> to learn how to install YOURLS</p>');
}
// Check if config.php was properly updated for 1.4
if (!defined('YOURLS_DB_PREFIX')) {
    yourls_die('<p class="error">Your <tt>config.php</tt> does not contain all the required constant definitions.</p><p>Please check <tt>config-sample.php</tt> and update your config accordingly, there are new stuffs!</p>');
}
// Define core constants that have not been user defined in config.php
// physical path of YOURLS root
if (!defined('YOURLS_ABSPATH')) {
    define('YOURLS_ABSPATH', str_replace('\\', '/', dirname(dirname(__FILE__))));
}
// physical path of includes directory
if (!defined('YOURLS_INC')) {
    define('YOURLS_INC', YOURLS_ABSPATH . '/includes');
}
// physical path of user directory
if (!defined('YOURLS_USERDIR')) {
    define('YOURLS_USERDIR', YOURLS_ABSPATH . '/user');
}
// URL of user directory

/**
 * Handle plugin administration page
 *
 */
function yourls_plugin_admin_page($plugin_page)
{
    global $ydb;
    // Check the plugin page is actually registered
    if (!isset($ydb->plugin_pages[$plugin_page])) {
        yourls_die('This page does not exist. Maybe a plugin you thought was activated is inactive?', 'Invalid link');
    }
    // Draw the page itself
    yourls_do_action('load-' . $plugin_page);
    yourls_html_head('plugin_page_' . $plugin_page, $ydb->plugin_pages[$plugin_page]['title']);
    yourls_html_logo();
    yourls_html_menu();
    call_user_func($ydb->plugin_pages[$plugin_page]['function']);
    yourls_html_footer();
    die;
}

/**
 * Display a page
 *
 */
function yourls_page($page)
{
    $include = YOURLS_ABSPATH . "/pages/{$page}.php";
    if (!file_exists($include)) {
        yourls_die("Page '{$page}' not found", 'Not found', 404);
    }
    yourls_do_action('pre_page', $page);
    include_once $include;
    yourls_do_action('post_page', $page);
    die;
}

/**
 * Check for maintenance mode. If yes, die. See yourls_maintenance_mode(). Stolen from WP.
 *
 */
function yourls_check_maintenance_mode()
{
    $file = YOURLS_ABSPATH . '/.maintenance';
    if (!file_exists($file) || yourls_is_upgrading() || yourls_is_installing()) {
        return;
    }
    global $maintenance_start;
    include_once $file;
    // If the $maintenance_start timestamp is older than 10 minutes, don't die.
    if (time() - $maintenance_start >= 600) {
        return;
    }
    // Use any /user/maintenance.php file
    if (file_exists(YOURLS_USERDIR . '/maintenance.php')) {
        include_once YOURLS_USERDIR . '/maintenance.php';
        die;
    }
    // https://www.youtube.com/watch?v=Xw-m4jEY-Ns
    $title = yourls__('Service temporarily unavailable');
    $message = yourls__('Our service is currently undergoing scheduled maintenance.') . "</p>\n<p>" . yourls__('Things should not last very long, thank you for your patience and please excuse the inconvenience');
    yourls_die($message, $title, 503);
}

/**
 * Die with a DB error message
 *
 * @TODO in version 1.8 : use a new localized string, specific to the problem (ie: "DB is dead")
 *
 * @since 1.7.1
 */
function yourls_db_dead()
{
    // Use any /user/db_error.php file
    if (file_exists(YOURLS_USERDIR . '/db_error.php')) {
        include_once YOURLS_USERDIR . '/db_error.php';
        die;
    }
    yourls_die(yourls__('Incorrect DB config, or could not connect to DB'), yourls__('Fatal error'), 503);
}

function yourls_check_IP_flood($ip = '')
{
    if (defined('YOURLS_FLOOD_DELAY_SECONDS') && YOURLS_FLOOD_DELAY_SECONDS === 0 || !defined('YOURLS_FLOOD_DELAY_SECONDS')) {
        return true;
    }
    $ip = $ip ? yourls_sanitize_ip($ip) : yourls_get_IP();
    // Don't throttle whitelist IPs
    if (defined('YOURLS_FLOOD_IP_WHITELIST' && YOURLS_FLOOD_IP_WHITELIST)) {
        $whitelist_ips = explode(',', YOURLS_FLOOD_IP_WHITELIST);
        foreach ($whitelist_ips as $whitelist_ip) {
            $whitelist_ip = trim($whitelist_ip);
            if ($whitelist_ip == $ip) {
                return true;
            }
        }
    }
    // Don't throttle logged in users
    if (yourls_is_private()) {
        if (yourls_is_valid_user() === true) {
            return true;
        }
    }
    global $ydb;
    $table = YOURLS_DB_TABLE_URL;
    $lasttime = $ydb->get_var("SELECT `timestamp` FROM {$table} WHERE `ip` = '{$ip}' ORDER BY `timestamp` DESC LIMIT 1");
    if ($lasttime) {
        $now = date('U');
        $then = date('U', strtotime($lasttime));
        if ($now - $then <= YOURLS_FLOOD_DELAY_SECONDS) {
            // Flood!
            yourls_die('Too many URLs added too fast. Slow down please.', 'Forbidden', 403);
        }
    }
    return true;
}

function yourls_check_maintenance_mode()
{
    // TODO: all cases that always display the sites (is_admin but not is_ajax?)
    if (1) {
        return;
    }
    // first case: /user/maintenance.php file
    if (file_exists(YOURLS_USERDIR . '/maintenance.php')) {
        include YOURLS_USERDIR . '/maintenance.php';
        die;
    }
    // second case: option in DB
    if (yourls_get_option('maintenance_mode') !== false) {
        require_once YOURLS_INC . '/functions-html.php';
        $title = 'Service temporarily unavailable';
        $message = 'Our service is currently undergoing scheduled maintenance.</p>
		<p>Things should not last very long, thank you for your patience and please excuse the inconvenience';
        yourls_die($message, $title, 503);
    }
}