<?php declare(strict_types=1);

const USERNAME_REGEX = '^.{1,1024}$';
const PASSWORD_REGEX = '^(?=.*[\p{Ll}])(?=.*[\p{Lu}])(?=.*[\p{N}]).{8,1024}|.{10,1024}$';

const PLACEHOLDER_USERNAME = 'lain';
const PLACEHOLDER_PASSWORD = '••••••••••••••••••••••••';

// Password storage security
const ALGO_PASSWORD = PASSWORD_ARGON2ID;
const OPTIONS_PASSWORD = [
	'memory_cost' => 65536,
	'time_cost' => 4,
	'threads' => 64,
];

function checkUsernameFormat(string $username): void {
	if (preg_match('/' . USERNAME_REGEX . '/Du', $username) !== 1)
		output(403, 'Username malformed.');
}

function checkPasswordFormat(string $password): void {
	if (preg_match('/' . PASSWORD_REGEX . '/Du', $password) !== 1)
		output(403, 'Password malformed.');
}

function hashUsername(string $username): string {
	return base64_encode(sodium_crypto_pwhash(32, $username, hex2bin(query('select', 'params', ['name' => 'username_salt'], 'value')[0]), 2**10, 2**14, SODIUM_CRYPTO_PWHASH_ALG_ARGON2ID13));
}

function hashPassword(string $password): string {
	return password_hash($password, ALGO_PASSWORD, OPTIONS_PASSWORD);
}

function usernameExists(string $username): bool {
	return isset(query('select', 'users', ['username' => $username], 'id')[0]);
}

function checkPassword(string $id, string $password): bool {
	return password_verify($password, query('select', 'users', ['id' => $id], 'password')[0]);
}

function outdatedPasswordHash(string $id): bool {
	return password_needs_rehash(query('select', 'users', ['id' => $id], 'password')[0], ALGO_PASSWORD, OPTIONS_PASSWORD);
}

function changePassword(string $id, string $password): void {
	DB->prepare('UPDATE users SET password = :password WHERE id = :id')
		->execute([':password' => hashPassword($password), ':id' => $id]);
}

function stopSession(): void {
	if (session_status() === PHP_SESSION_ACTIVE)
		session_destroy();
}

function logout(): never {
	stopSession();

	header('Clear-Site-Data: "*"');

	redir();
}

function setupDisplayUsername(string $display_username): void {
	$nonce = random_bytes(24);
	$key = sodium_crypto_aead_xchacha20poly1305_ietf_keygen();
	$cyphertext = sodium_crypto_aead_xchacha20poly1305_ietf_encrypt(
		htmlspecialchars($display_username),
		'',
		$nonce,
		$key
	);

	$_SESSION['display-username-nonce'] = $nonce;
	setcookie(
		'display-username-decryption-key',
		base64_encode($key),
		[
			'expires' => time() + 432000,
			'path' => CONF['common']['prefix'] . '/',
			'secure' => true,
			'httponly' => true,
			'samesite' => 'Strict'
		]
	);
	$_SESSION['display-username-cyphertext'] = $cyphertext;
}

function authDeleteUser(string $user_id): void {
	$user_services = explode(',', query('select', 'users', ['id' => $user_id], 'services')[0]);

	foreach (SERVICES_USER as $service)
		if (in_array($service, $user_services, true) AND CONF['common']['services'][$service] !== 'enabled')
			output(503, sprintf(_('Your account can\'t be deleted because the %s service is currently unavailable.'), '<em>' . PAGES[$service]['index']['title'] . '</em>'));

	if (in_array('reg', $user_services, true))
		foreach (query('select', 'registry', ['username' => $user_id], 'domain') as $domain)
			regDeleteDomain($domain, $user_id);

	if (in_array('ns', $user_services, true))
		foreach (query('select', 'zones', ['username' => $user_id], 'zone') as $zone)
			nsDeleteZone($zone, $user_id);

	if (in_array('ht', $user_services, true)) {
		foreach (query('select', 'sites', ['username' => $user_id]) as $site)
			htDeleteSite($site['address'], $site['type'], $user_id);

		exescape([
			CONF['ht']['sudo_path'],
			'-u',
			CONF['ht']['tor_user'],
		    '--',
			CONF['ht']['rm_path'],
			'-r',
			'--',
			CONF['ht']['tor_keys_path'] . '/' . $user_id,
		], result_code: $code);
		if ($code !== 0)
			output(500, 'Can\'t remove Tor keys directory.');

		removeDirectory(CONF['ht']['tor_config_path'] . '/' . $user_id);

		exescape([
			CONF['ht']['sudo_path'],
			'-u',
			CONF['ht']['sftpgo_user'],
			'--',
			CONF['ht']['rm_path'],
			'-r',
			'--',
			CONF['ht']['ht_path'] . '/fs/' . $user_id
		], result_code: $code);
		if ($code !== 0)
			output(500, 'Can\'t remove user\'s directory.');

		query('delete', 'ssh-keys', ['username' => $user_id]);
	}

	query('delete', 'users', ['id' => $user_id]);
}

function rateLimit(): void {
	if ((PAGE_METADATA['tokens_account_cost'] ?? 0) > 0)
		rateLimitAccount(PAGE_METADATA['tokens_account_cost']);

	if ((PAGE_METADATA['tokens_instance_cost'] ?? 0) > 0)
		rateLimitInstance(PAGE_METADATA['tokens_instance_cost']);
}

const MAX_ACCOUNT_TOKENS = 86400;
function rateLimitAccount(int $requestedTokens): int {
	// Get
	$userData = query('select', 'users', ['id' => $_SESSION['id']]);
	$tokens = $userData[0]['bucket_tokens'];
	$bucketLastUpdate = $userData[0]['bucket_last_update'];

	// Compute
	$tokens = min(MAX_ACCOUNT_TOKENS, $tokens + (time() - $bucketLastUpdate));

	if ($requestedTokens > 0) {
		if ($requestedTokens > $tokens)
			output(453, _('Account rate limit reached, try again later.'));

		$tokens -= $requestedTokens;

		// Update
		DB->prepare('UPDATE users SET bucket_tokens = :bucket_tokens, bucket_last_update = :bucket_last_update WHERE id = :id')
		->execute([
			':bucket_tokens' => $tokens,
			':bucket_last_update' => time(),
			':id' => $_SESSION['id']
		]);
	}

	return $tokens;
}

function rateLimitInstance(int $requestedTokens): void {
	// Get
	$tokens = query('select', 'params', ['name' => 'instance_bucket_tokens'], 'value')[0];
	$bucketLastUpdate = query('select', 'params', ['name' => 'instance_bucket_last_update'], 'value')[0];

	// Compute
	$tokens = min(86400, $tokens + (time() - $bucketLastUpdate));

	if ($requestedTokens > $tokens)
		output(453, _('Global rate limit reached, try again later.'));

	$tokens -= $requestedTokens;

	// Update
	DB->prepare("UPDATE params SET value = :bucket_tokens WHERE name = 'instance_bucket_tokens';")
	->execute([':bucket_tokens' => $tokens]);

	DB->prepare("UPDATE params SET value = :bucket_last_update WHERE name = 'instance_bucket_last_update';")
	->execute([':bucket_last_update' => time()]);
}