<?php

class MiniLinux
{

	const PROPERTY_KEY_FETCHTIME = 'ml-list-fetch';

	const PROPERTY_DEFAULT_BOOT = 'ml-default';

	const PROPERTY_DEFAULT_BOOT_EFFECTIVE = 'ml-default-eff';

	const INVALID = 'invalid';

	const INSTALL_MISSING = 0;

	const INSTALL_OK = 1;

	const INSTALL_BROKEN = 2;

	/*
	 * Update of available versions by querying sources
	 */

	/**
	 * Query all known sources for metadata
	 * @return int number of sources query was just initialized for
	 */
	public static function updateList(): int
	{
		$stamp = time();
		$last = Property::get(self::PROPERTY_KEY_FETCHTIME);
		if ($last !== false && $last + 3 > $stamp)
			return 0; // In progress...
		Property::set(self::PROPERTY_KEY_FETCHTIME, $stamp, 10);
		Database::exec('LOCK TABLES callback WRITE,
			minilinux_source WRITE, minilinux_branch WRITE, minilinux_version WRITE');
		Database::exec('UPDATE minilinux_source SET taskid = UUID()');
		$cutoff = time() - 3600;
		Database::exec("UPDATE minilinux_version
    		INNER JOIN minilinux_branch USING (branchid)
    		INNER JOIN minilinux_source USING (sourceid)
			SET orphan = orphan + 1
			WHERE minilinux_source.lastupdate < $cutoff AND orphan < 100");
		$list = Database::queryAll('SELECT sourceid, url, taskid FROM minilinux_source');
		foreach ($list as $source) {
			Taskmanager::submit('DownloadText', array(
				'id' => $source['taskid'],
				'url' => $source['url'],
			), true);
			TaskmanagerCallback::addCallback($source['taskid'], 'mlGotList', $source['sourceid']);
		}
		Database::exec('UNLOCK TABLES');
		return count($list);
	}

	/**
	 * Called when downloading metadata from a specific update source is finished
	 *
	 * @param array $task task structure
	 * @param string $sourceid see minilinux_source table
	 */
	public static function listDownloadCallback(array $task, string $sourceid): void
	{
		if (!Taskmanager::isFinished($task))
			return;
		$taskId = $task['id'];
		$data = json_decode($task['data']['content'] ?? '', true);
		if (!is_array($data) || empty($data['systems'])) {
			EventLog::warning('Cannot download Linux version meta data for ' . $sourceid,
				($task['data']['error'] ?? '') . "\n\nContent:\n" . ($task['data']['content'] ?? ''));
			$lastupdate = 'lastupdate';
		} else {
			if (is_array($data['systems'])) {
				self::addBranches($sourceid, $data['systems']);
			}
			$lastupdate = 'UNIX_TIMESTAMP()';
		}
		Database::exec("UPDATE minilinux_source SET lastupdate = $lastupdate, taskid = NULL
			WHERE sourceid = :sourceid AND taskid = :taskid",
			['sourceid' => $sourceid, 'taskid' => $taskId]);
		// Clean up -- delete orphaned versions that are not installed
		Database::exec('DELETE FROM minilinux_version WHERE orphan > 4 AND installed = :missing',
			['missing' => self::INSTALL_MISSING]);
		// FKC makes sure we only delete orphaned ones
		Database::exec('DELETE IGNORE FROM minilinux_branch WHERE 1', [], true);
	}

	private static function addBranches($sourceid, $systems)
	{
		foreach ($systems as $system) {
			if (!self::isValidIdPart($system['id']))
				continue;
			$branchid = $sourceid . '/' . $system['id'];
			$title = mb_substr(empty($system['title']) ? $branchid : $system['title'], 0, 150);
			$description = $system['description'] ?? '';
			$color = $system['color'] ?? '';
			if (!empty($system['versions']) && is_array($system['versions'])) {
				Database::exec('INSERT INTO minilinux_branch (branchid, sourceid, title, color, description)
					VALUES (:branchid, :sourceid, :title, :color, :description)
					ON DUPLICATE KEY UPDATE title = VALUES(title), color = VALUES(color), description = VALUES(description)', [
					'branchid' => $branchid,
					'sourceid' => $sourceid,
					'title' => $title,
					'color' => $color,
					'description' => $description,
				]);
				self::addVersions($branchid, $system['versions']);
			} else {
				// Empty branch - only update metadata if branch exists locally
				Database::exec('UPDATE minilinux_branch
					SET title = :title, color = :color, description = :description
					WHERE sourceid = :sourceid AND branchid = :branchid', [
					'branchid' => $branchid,
					'sourceid' => $sourceid,
					'title' => $title,
					'color' => $color,
					'description' => $description,
				]);
			}
		}
	}

	private static function addVersions($branchid, $versions)
	{
		foreach ($versions as $version) {
			self::addVersion($branchid, $version);
		}
	}

	private static function addVersion($branchid, $version)
	{
		if (!self::isValidIdPart($version['version'])) {
			error_log("Ignoring version {$version['version']} from $branchid: Invalid characters in ID");
			return;
		}
		if (empty($version['files']) && empty($version['cmdline'])) {
			error_log("Ignoring version {$version['version']} from $branchid: Neither file list nor command line");
			return;
		}
		$versionid = $branchid . '/' . $version['version'];
		$title = $version['title'] ?? '';
		$description = $version['description'] ?? '';
		$dateline = empty($version['releasedate']) ? time() : (int)$version['releasedate'];
		unset($version['version'], $version['title'], $version['releasedate']);
		// Sanitize files array
		if (!isset($version['files']) || !is_array($version['files'])) {
			unset($version['files']);
		} else {
			foreach (array_keys($version['files']) as $key) {
				$file =& $version['files'][$key];
				if (empty($file['name'])) {
					error_log("Ignoring version {$version['version']} from $branchid: Entry in file list has missing file name");
					return;
				}
				if ($file['name'] === 'menu.txt' || $file['name'] === 'menu-debug.txt') {
					unset($version['files'][$key]);
					continue;
				}
				if (empty($file['gpg'])) {
					error_log("Ignoring version {$version['version']} from $branchid: {$file['name']} has no GPG signature");
					return;
				}
				if (preg_match(',/\.\.|\.\./|/|\x00,', $file['name']) > 0) { // Invalid chars
					error_log("Ignoring version {$version['version']} from $branchid: {$file['name']} contains invalid characters");
					return;
				}
				if (isset($file['md5'])) {
					$file['md5'] = strtolower($file['md5']);
				}
			}
			unset($file);
			$version['files'] = array_values($version['files']);
		}
		$data = json_encode($version);
		Database::exec('INSERT INTO minilinux_version (versionid, branchid, title, description, dateline, data, orphan)
					VALUES (:versionid, :branchid, :title, :description, :dateline, :data, 0)
					ON DUPLICATE KEY UPDATE title = VALUES(title), description = VALUES(description),
					                        dateline = VALUES(dateline), data = VALUES(data), orphan = 0', [
			'versionid' => $versionid,
			'branchid' => $branchid,
			'title' => mb_substr($title, 0, 150),
			'description' => $description,
			'dateline' => $dateline,
			'data' => $data,
		]);
	}

	private static function isValidIdPart(string $str): bool
	{
		return preg_match('/^[a-z0-9_\-]+$/', $str) > 0;
	}

	/*
	 * Download of specific version
	 */

	public static function validateDownloadTask(string $versionid, ?string $taskid): ?string
	{
		if ($taskid === null)
			return null;
		$task = Taskmanager::status($taskid);
		if (Taskmanager::isTask($task) && !Taskmanager::isFailed($task)
				&& (is_dir(CONFIG_HTTP_DIR . '/' . $versionid) || !Taskmanager::isFinished($task)))
			return $task['id'];
		Database::exec('UPDATE minilinux_version SET taskid = NULL
				WHERE versionid = :versionid AND taskid = :taskid',
			['versionid' => $versionid, 'taskid' => $taskid]);
		return null;
	}

	/**
	 * Download the files for the given version id
	 */
	public static function downloadVersion(string $versionid): ?string
	{
		$ver = Database::queryFirst('SELECT s.url, s.pubkey, v.versionid, v.taskid, v.data FROM minilinux_version v
			INNER JOIN minilinux_branch b USING (branchid)
			INNER JOIN minilinux_source s USING (sourceid)
			WHERE versionid = :versionid',
			['versionid' => $versionid]);
		if ($ver === false)
			return null;
		$taskid = self::validateDownloadTask($versionid, $ver['taskid']);
		if ($taskid !== null)
			return $taskid;
		$data = json_decode($ver['data'], true);
		if (!is_array($data)) {
			EventLog::warning("Cannot download Linux '$versionid': Corrupted meta data.", $ver['data']);
			return null;
		}
		if (empty($data['files']))
			return null;
		$list = [];
		$legacyDir = preg_replace(',^[^/]*/,', '', $versionid);
		foreach ($data['files'] as $file) {
			if (empty($file['name']))
				continue;
			$list[] = [
				'id' => self::fileToId($versionid, $file['name']),
				'url' => empty($file['url'])
					? ($ver['url'] . '/' . $legacyDir . '/' . $file['name'])
					: ($ver['url'] . '/' . $file['url']),
				'fileName' => $file['name'],
				'gpg' => $file['gpg'],
			];
		}
		$uuid = Util::randomUuid();
		Database::exec('LOCK TABLES minilinux_version WRITE');
		$aff = Database::exec('UPDATE minilinux_version SET taskid = :taskid WHERE versionid = :versionid AND taskid IS NULL',
			['taskid' => $uuid, 'versionid' => $versionid]);
		$task = false;
		if ($aff > 0) {
			$task = Taskmanager::submit('DownloadFiles', [
				'id' => $uuid,
				'baseDir' => CONFIG_HTTP_DIR . '/' . $versionid,
				'gpgPubKey' => $ver['pubkey'],
				'files' => $list,
			]);
			if (Taskmanager::isFailed($task)) {
				$task = false;
			} else {
				$task = (string)$task['id'];
			}
		}
		Database::exec('UNLOCK TABLES');
		if ($task !== false) {
			// Callback for db column
			TaskmanagerCallback::addCallback($task, 'mlGotLinux', $versionid);
			self::checkStage4($data);
		}
		// Race - someone else wrote a taskid to DB, just call self again to get that one
		if ($aff === 0)
			return self::downloadVersion($versionid);
		return $task;
	}

	public static function fileToId(string $versionid, string $fileName): string
	{
		return 'x' . substr(md5($fileName . $versionid), 0, 8);
	}

	/*
	 * Check status, availability of updates
	 */

	/**
	 * Generate messages regarding setup und update availability.
	 * @return bool true if severe problems were found, false otherwise
	 */
	public static function generateUpdateNotice(): bool
	{
		// Messages in here are with module name, as required by the
		// main-warning hook.
		$default = Property::get(self::PROPERTY_DEFAULT_BOOT);
		if ($default === false) {
			Message::addError('minilinux.no-default-set', true);
			return true;
		}
		$installed = self::updateCurrentBootSetting();
		$effective = Property::get(self::PROPERTY_DEFAULT_BOOT_EFFECTIVE);
		$slashes = substr_count($default, '/');
		if ($slashes === 1) {
			// Brônche, always latest version
			$latest = Database::queryFirst('SELECT versionid FROM minilinux_version
				WHERE branchid = :branchid ORDER BY dateline DESC', ['branchid' => $default]);
			if ($latest === false) {
				Message::addError('minilinux.default-is-invalid', true);
				return true;
			} elseif ($latest['versionid'] !== $effective) {
				Message::addInfo('minilinux.default-update-available', true, $default, $latest['versionid']);
			}
		} elseif ($slashes === 2) {
			// Specific version selected
			if ($effective === self::INVALID) {
				Message::addError('minilinux.default-is-invalid', true);
				return true;
			}
		}
		if (!$installed) {
			Message::addError('minilinux.default-not-installed', true, $default);
			return true;
		}
		return false;
	}

	/**
	 * Update the effective current default version to boot.
	 * If the version does not exist, it is set to INVALID.
	 * Function returns whether the currently selected version is
	 * actually installed locally.
	 * @return bool true if installed locally, false otherwise
	 */
	public static function updateCurrentBootSetting(): bool
	{
		$default = Property::get(self::PROPERTY_DEFAULT_BOOT);
		if ($default === false)
			return false;
		$slashes = substr_count($default, '/');
		if ($slashes === 2) {
			// Specific version
			$ver = Database::queryFirst('SELECT versionid, installed FROM minilinux_version
				WHERE versionid = :versionid', ['versionid' => $default]);
		} elseif ($slashes === 1) {
			// Latest from branch
			$ver = Database::queryFirst('SELECT versionid, installed FROM minilinux_version
				WHERE branchid = :branchid AND installed = :ok ORDER BY dateline DESC', ['branchid' => $default, 'ok' => self::INSTALL_OK]);
		} else {
			// Unknown
			return false;
		}
		// Determine state
		if ($ver === false) { // Doesn't exist
			Property::set(self::PROPERTY_DEFAULT_BOOT_EFFECTIVE, self::INVALID);
			return false;
		}
		Property::set(self::PROPERTY_DEFAULT_BOOT_EFFECTIVE, $ver['versionid']);
		return $ver['installed'] != self::INSTALL_MISSING;
	}

	public static function linuxDownloadCallback($task, $versionid)
	{
		self::setInstalledState($versionid, $task['statusCode'] === 'TASK_FINISHED' ? self::INSTALL_OK : self::INSTALL_BROKEN);
	}

	public static function setInstalledState($versionid, int $installed): void
	{
		Database::exec('UPDATE minilinux_version SET installed = :installed WHERE versionid = :versionid', [
			'versionid' => $versionid,
			'installed' => $installed,
		]);
		if ($installed === self::INSTALL_OK) {
			$res = Database::queryFirst('SELECT Count(*) AS cnt FROM minilinux_version WHERE installed = :ok',
				['ok' => self::INSTALL_OK]);
			if ($res['cnt'] == 1) {
				self::setDefaultVersion($versionid);
			}
		}
	}

	public static function queryAllVersionsByBranch(): array
	{
		$list = [];
		$res = Database::simpleQuery('SELECT branchid, versionid, title, Length(description) AS desclen,
       		dateline, orphan, taskid, installed
			FROM minilinux_version ORDER BY branchid, dateline, versionid');
		foreach ($res as $row) {
			$list[$row['branchid']][$row['versionid']] = $row;
		}
		return $list;
	}

	public static function setDefaultVersion($versionId)
	{
		Property::set(MiniLinux::PROPERTY_DEFAULT_BOOT, $versionId);
		self::updateCurrentBootSetting();
		// Legacy PXELINUX boot menu (TODO: Remove this when we get rid of PXELINUX support)
		$task = Taskmanager::submit('Symlink', [
			'target' => $versionId,
			'linkname' => CONFIG_HTTP_DIR . '/default',
		]);
		if ($task !== false) {
			Taskmanager::release($task);
		}
	}

	/**
	 * Check whether an optionally required stage4 is available.
	 * Return true if there is no stage4, otherwise check filesystem,
	 * or try to request from local dnbd3-server.
	 *
	 * @param array $data decoded data column from minilinux_version
	 * @param string[] $errors in array of error messages if not available
	 * @return bool true if stage4 is available or none required
	 */
	public static function checkStage4(array $data, &$errors = false): bool
	{
		$errors = [];
		$image = false;
		$rid = 0;
		foreach (['agnostic', 'efi', 'bios'] as $type) {
			if (!isset($data[$type]) || !isset($data[$type]['commandLine']))
				continue;
			if (!preg_match('/\bslx\.stage4\.path=(\S+)/', $data[$type]['commandLine'], $out))
				continue;
			$image = $out[1];
			if (preg_match('/\bslx\.stage4\.rid=(\d+)/', $data[$type]['commandLine'], $out)) {
				$rid = (int)$out[1];
			}
			break;
		}
		if ($image === false)
			return true; // No stage4
		if ($rid === 0) {
			// Get latest local revision
			foreach (glob(CONFIG_VMSTORE_DIR . '/' . $image . '.r*', GLOB_NOSORT) as $file) {
				if (preg_match('/\.r(\d+)$/', $file, $out)) {
					$cmp = (int)$out[1];
					if ($cmp > $rid) {
						$rid = $cmp;
					}
				}
			}
		}
		if ($rid > 0 && file_exists(CONFIG_VMSTORE_DIR . '/' . $image . '.r' . $rid)
				&& !file_exists(CONFIG_VMSTORE_DIR . '/' . $image . '.r' . $rid . '.map')) {
			// Accept if image exists locally and no map file (map file would mean incomplete)
			return true;
		}
		// Not found locally -- try to replicate
		$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
		if ($sock === false) {
			$errors[] = 'Error creatring socket to connect to dnbd3-server';
			return false;
		}
		socket_set_option($sock, SOL_SOCKET, SO_SNDTIMEO, array('sec' => 1, 'usec' => 0));
		socket_set_option($sock, SOL_SOCKET, SO_RCVTIMEO, array('sec' => 5, 'usec' => 0));
		if (@socket_connect($sock, '127.0.0.1', 5003) === false) {
			$errors[] = 'Could not connect to local dnbd3-server';
			socket_close($sock);
			return false;
		}
		// proto-version(16), image name\0, rid(16), flags(8)
		$payload = pack('vA*xvC', 3, $image, $rid, 0);
		// magic(16), cmd(16), payload-len(32), offset(64), handle(64) XXX 32Bit compat
		$packet = pack('A*vVVVVV', 'sr', 2, strlen($payload), 0, 0, 1234, 0) . $payload;
		if (!socket_send($sock, $packet, strlen($packet), 0)) {
			$errors[] = 'Cannot send request to dnbd3-server';
			socket_close($sock);
			return false;
		}
		$len = socket_recv($sock, $reply, 16, MSG_WAITALL);
		if ($len === 0) {
			$errors[] = 'Local dnbd3-server cannot replicate required stage4 from master-server';
			socket_close($sock);
			return false;
		}
		if ($len !== 16) {
			$errors[] = 'Incomplete reply received from local dnbd3-server. Stage4 might not replicate!';
			socket_close($sock);
			return false;
		}
		socket_close($sock);
		// Try to decode header
		$reply = unpack('A2magic/vcmd/Vsize/Vhandlelow/Vhandlehigh', $reply);
		if ($reply['magic'] !== 'sr') {
			$errors[] = 'Reply has wrong magic';
		}
		if ($reply['cmd'] !== 2) {
			$errors[] = 'Reply is not CMD_IMAGE_REPLY';
		}
		return empty($errors);
	}

	/**
	 * Determine by which menus/locations each MiniLinux version is being used.
	 */
	public static function getBootMenuUsage(): array
	{
		if (!Module::isAvailable('serversetup') || !class_exists('BootEntryHook'))
			return [];
		$res = Database::simpleQuery("SELECT be.entryid, be.data,
       		GROUP_CONCAT(DISTINCT me.menuid) AS menus,
       		GROUP_CONCAT(DISTINCT ml.locationid) AS locations
			FROM serversetup_bootentry be
			LEFT JOIN serversetup_menuentry me USING (entryid)
			LEFT JOIN serversetup_menu_location ml USING (menuid)
			WHERE module = 'minilinux'
			GROUP BY be.data");
		$return = [];
		$usedMenuIds = [];
		foreach ($res as $row) {
			$data = json_decode($row['data'], true);
			if (!isset($data['id']))
				continue;
			$id = self::resolveEntryId($data['id']);
			$new = [
				'entryids' => [$row['entryid']],
				'menus' => explode(',', $row['menus'] ?? ''),
				'locations' => explode(',', $row['locations'] ?? ''),
			];
			$usedMenuIds = array_merge($usedMenuIds, $new['menus']);
			if (isset($return[$id])) {
				$return[$id] = array_merge_recursive($return[$id], $new);
			} else {
				$return[$id] = $new;
			}
		}
		// Build id => title map for menus
		$res = Database::simpleQuery("SELECT menuid, title FROM serversetup_menu m
				WHERE menuid IN (:menuid)", ['menuid' => array_unique($usedMenuIds)]);
		$menus = [];
		foreach ($res as $row) {
			$menus[$row['menuid']] = $row['title'];
		}
		// Build output array
		foreach ($return as &$item) {
			$item['locations'] = array_map(function ($i) {
				return ['locationid' => $i, 'locationname' => Location::getName($i)];
			}, array_unique(array_filter($item['locations'], 'is_numeric')));
			$item['menus'] = array_map(function ($i) use ($menus) {
				return ['menuid' => $i, 'menuname' => $menus[$i]];
			}, array_unique(array_filter($item['menus'], 'is_numeric')));
			$item['locationCount'] = count($item['locations']);
			$item['menuCount'] = count($item['menus']);
			$item['entryCount'] = count($item['entryids']);
		}
		return $return;
	}

	/**
	 * Take a configured versionid from a bootentry (serversetup module) and translate
	 * it, in case it's "default" or just a branch name.
	 */
	private static function resolveEntryId(string $id): string
	{
		if ($id === 'default') { // Special case
			$id = Property::get(MiniLinux::PROPERTY_DEFAULT_BOOT_EFFECTIVE);
		}
		if (substr_count($id, '/') < 2) {
			// Maybe this is a branchid, which means latest from according branch (installed only)
			$res = Database::queryFirst('SELECT versionid FROM minilinux_version WHERE branchid = :id AND installed = :ok
				ORDER BY dateline DESC LIMIT 1',
				['id' => $id, 'ok' => self::INSTALL_OK]);
			if ($res !== false) {
				$id = $res['versionid'];
			}
		}
		return $id;
	}

}