<?php
umask(0077);

set_error_handler(function ($level, $message, $file = '', $line = 0) {
	throw new ErrorException($message, 0, $level, $file, $line);
});
set_exception_handler(function ($e) {
	error_log($e);
	http_response_code(500);
	echo '<h1>Error</h1>An error occured.';
});
register_shutdown_function(function () { // Also catch fatal errors
	if (($error = error_get_last()) !== NULL)
		throw new ErrorException($error['message'], 0, $error['type'], $error['file'], $error['line']);
});

const ROOT_PATH = __DIR__;
define('CONF', parse_ini_file(ROOT_PATH . '/config.ini', true, INI_SCANNER_TYPED));

define('DB', new PDO('sqlite:' . ROOT_PATH . '/db/servnest.db'));
DB->exec('PRAGMA foreign_keys = ON;');
DB->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

date_default_timezone_set('UTC');

foreach (explode(',', preg_replace('/[A-Z0-9]|q=|;|-|\./', '', $_SERVER['HTTP_ACCEPT_LANGUAGE'] ?? '')) as $client_locale)
	if (in_array($client_locale, array_diff(scandir(ROOT_PATH . '/locales'), ['..', '.']), true)) {
		$locale = $client_locale;
		break;
	}
define('LOCALE', $locale ?? 'en');
putenv('LANG=C.UTF-8');
setlocale(LC_MESSAGES, 'C.UTF-8');
bindtextdomain('messages', ROOT_PATH . '/locales/' . LOCALE);
header('Content-Language: ' . LOCALE);

const SERVICES_USER = ['reg', 'ns', 'ht'];

const LF = "\n";

const PLACEHOLDER_DOMAIN = 'example'; // From RFC2606: Reserved Top Level DNS Names > 2. TLDs for Testing, & Documentation Examples
const PLACEHOLDER_IPV6 = '2001:db8::3'; // From RFC3849: IPv6 Address Prefix Reserved for Documentation
const PLACEHOLDER_IPV4 = '203.0.113.42'; // From RFC5737: IPv4 Address Blocks Reserved for Documentation

foreach (array_diff(scandir(ROOT_PATH . '/fn'), ['..', '.']) as $file)
	require ROOT_PATH . '/fn/' . $file;

require ROOT_PATH . '/pages.php';

if ($_SERVER['REQUEST_URI'] === '/sftpgo-auth.php')
	return;

$pageAddress = substr($_SERVER['REQUEST_URI'], strlen(CONF['common']['prefix']) + 1);
if (strpos($pageAddress, '?') !== false) {
	parse_str(substr($pageAddress, strpos($pageAddress, '?') + 1), $_GET);
	$pageAddress = substr($pageAddress, 0, strpos($pageAddress, '?'));
}
define('PAGE_URL', $pageAddress);
define('PAGE_ADDRESS', $pageAddress . ((substr($pageAddress, -1) === '/' OR $pageAddress === '') ? 'index' : ''));
define('PAGE_LINEAGE', explode('/', PAGE_ADDRESS));
define('SERVICE', dirname(PAGE_ADDRESS));

function getPageInformations($pages, $pageElements) {
	if (!isset($pages['index']) OR $pageElements[0] === 'index')
		return [
			'titles_lineage' => [$pages[$pageElements[0]]['title'] ?? false],
			'page_metadata' => $pages[$pageElements[0]] ?? NULL,
			'terminal' => $pageElements[0] !== 'index'
		];
	$result = $pages['index']['title'];
	if (!isset($pageElements[1]))
		unset($pages['index']);
	else
		$pages = $pages[array_shift($pageElements)] ?? false;
	$results = getPageInformations($pages, $pageElements);
	$results['titles_lineage'][] = $result;
	return $results;
}
$pageInformations = getPageInformations(PAGES, PAGE_LINEAGE);
define('TITLES_LINEAGE', array_reverse($pageInformations['titles_lineage']));
define('PAGE_METADATA', $pageInformations['page_metadata']);
define('PAGE_TERMINAL', $pageInformations['terminal']);

if (!TITLES_LINEAGE[array_key_last(TITLES_LINEAGE)]) {
	http_response_code(404);
	exit('Page not found.');
}

if (isset($_SERVER['SERVER_NAME']) !== true)
	exit('Missing <code>$_SERVER[\'SERVER_NAME\']</code>');
if (in_array($_SERVER['SERVER_NAME'], CONF['common']['public_domains'], true) !== true)
	exit('The current <code>$_SERVER[\'SERVER_NAME\']</code> is not allowed in configuration.');
define('SERVER_NAME', $_SERVER['SERVER_NAME']);

const SESSION_COOKIE_NAME = 'servnest-session-key';
function startSession() {
	session_start([
		'name' => SESSION_COOKIE_NAME,
		'sid_length' => 64,
		'sid_bits_per_character' => 6,
		'cookie_secure' => true,
		'cookie_httponly' => true,
		'cookie_samesite' => 'Strict',
		'cookie_path' => CONF['common']['prefix'] . '/',
		'cookie_lifetime' => 432000, // = 60*60*24*5 = 5 days
		'gc_maxlifetime' => 10800,
		'use_strict_mode' => true,
		'use_cookies' => true,
		'use_only_cookies' => true,
	]);
}
if (isset($_COOKIE[SESSION_COOKIE_NAME]))
	startSession(); // Resume session

if (isset($_SESSION['id'])) {
	// Decrypt display username
	if (!isset($_COOKIE['display-username-decryption-key']))
		output(403, 'The display username decryption key has not been sent.');
	$decryption_result = htmlspecialchars(sodium_crypto_aead_xchacha20poly1305_ietf_decrypt(
		$_SESSION['display-username-cyphertext'],
		'',
		$_SESSION['display-username-nonce'],
		base64_decode($_COOKIE['display-username-decryption-key'])
	));
	if ($decryption_result === false)
		output(403, 'Unable to decrypt display username.');
	define('DISPLAY_USERNAME', $decryption_result);

	// Enable not already enabled services for this user
	$user_services = array_filter(explode(',', query('select', 'users', ['id' => $_SESSION['id']], 'services')[0]));
	foreach (SERVICES_USER as $service)
		if (!in_array($service, $user_services, true) AND CONF['common']['services'][$service] === 'enabled') {
			$user_services[] = $service;

			DB->prepare('UPDATE users SET services = :services WHERE id = :id')
			->execute([':services' => implode(',', $user_services), ':id' => $_SESSION['id']]);

			if ($service === 'ht')
				htSetupUserFs($_SESSION['id']);
		}
}

function displayFinalMessage($data) {
	if (isset($data['final_message'])) {
		echo $data['final_message'];
		unset($data['final_message']);
	}
}

if ($_POST !== []) {
	if (!in_array(CONF['common']['services']['auth'], ['enabled', 'no-registration'], true) OR (in_array(SERVICE, SERVICES_USER, true) AND CONF['common']['services'][SERVICE] !== 'enabled'))
		output(503, _('This service is currently under maintenance. No action can be taken on it until an administrator finishes repairing it.'));

	// Protect against cross-site request forgery if a POST request is received
	if (isset($_SERVER['HTTP_SEC_FETCH_SITE']) !== true)
		output(403, 'The <code>Sec-Fetch-Site</code> HTTP header is required when submitting a POST request to prevent Cross-Site Request Forgery (<abbr>CSRF</abbr>).');
	if (!in_array($_SERVER['HTTP_SEC_FETCH_SITE'], ['none', 'same-origin'], true))
		output(403, 'The <code>Sec-Fetch-Site</code> HTTP header must be <code>same-origin</code> or <code>none</code> when submitting a POST request to prevent Cross-Site Request Forgery (<abbr>CSRF</abbr>).');

	if (PAGE_METADATA['require-login'] ?? true !== false) {
		if (isset($_SESSION['id']) !== true)
			output(403, _('You need to be logged in to do this.'));
		if (isset(query('select', 'users', ['id' => $_SESSION['id']], 'id')[0]) !== true)
			output(403, _('This account doesn\'t exist anymore. Log out to end this ghost session.'));
	}

	if (file_exists(ROOT_PATH . '/pg-act/' . PAGE_ADDRESS . '.php'))
		require ROOT_PATH . '/pg-act/' . PAGE_ADDRESS . '.php';
}

function displayPage($data) {
	require ROOT_PATH . '/view.php';
	exit();
}
displayPage($data ??= NULL);