<?php

/**
 * Job state stored on disk (not in the database), so a restore that
 * replaces every table never loses track of its own progress.
 *
 * @package Shiftbox
 */

// phpcs:disable WordPress.WP.AlternativeFunctions, WordPress.PHP.NoSilencedErrors.Discouraged

defined('ABSPATH') || exit;

/**
 * A resumable job.
 */
class Shiftbox_Job
{

	/**
	 * Job id.
	 *
	 * @var string
	 */
	public $id;

	/**
	 * State.
	 *
	 * @var array
	 */
	public $data = array();

	/**
	 * Lock handle.
	 *
	 * @var resource|null
	 */
	private $lock;

	/**
	 * Constructor.
	 *
	 * @param string $id   Id.
	 * @param array  $data State.
	 */
	private function __construct($id, array $data)
	{
		$this->id   = $id;
		$this->data = $data;
	}

	/**
	 * Starts a new job. Fails if another job is running.
	 *
	 * @param string $type export|import.
	 * @param array  $args Initial state.
	 * @return Shiftbox_Job|WP_Error
	 */
	public static function create($type, array $args)
	{
		if (! Shiftbox_Storage::ensure()) {
			return new WP_Error('shiftbox_storage', __('The backup folder (uploads/shiftbox-backups) is not writable. Ask your host to allow PHP to write to the uploads folder.', 'shiftbox'));
		}
		$active = self::active();
		if ($active) {
			return new WP_Error('shiftbox_busy', __('Another backup or restore is running. Wait for it to finish or cancel it first.', 'shiftbox'));
		}
		$id  = gmdate('YmdHis') . '-' . strtolower(wp_generate_password(8, false));
		$dir = Shiftbox_Storage::jobs_dir() . '/' . $id;
		if (! wp_mkdir_p($dir)) {
			return new WP_Error('shiftbox_storage', __('Could not create a working folder inside uploads/shiftbox-backups.', 'shiftbox'));
		}
		$job = new self(
			$id,
			array_merge(
				array(
					'type'     => $type,
					'step'     => 'start',
					'progress' => 0,
					'message'  => '',
					'created'  => time(),
					'log'      => array(),
				),
				$args
			)
		);
		$job->save();
		self::set_active($id, $type);
		return $job;
	}

	/**
	 * Loads a job.
	 *
	 * @param string $id Id.
	 * @return Shiftbox_Job|null
	 */
	public static function load($id)
	{
		if (! is_string($id) || ! preg_match('/^\d{14}-[a-z0-9]{8}$/', $id)) {
			return null;
		}
		$file = Shiftbox_Storage::jobs_dir() . '/' . $id . '/state.json';
		if (! is_file($file)) {
			return null;
		}
		$data = wp_json_file_decode($file, array('associative' => true));
		return is_array($data) ? new self($id, $data) : null;
	}

	/**
	 * Working folder.
	 *
	 * @param string $file Optional file inside it.
	 * @return string
	 */
	public function path($file = '')
	{
		$dir = Shiftbox_Storage::jobs_dir() . '/' . $this->id;
		return $file ? $dir . '/' . $file : $dir;
	}

	/**
	 * Writes state atomically.
	 *
	 * @return void
	 */
	public function save()
	{
		$tmp = $this->path('state.json.tmp');
		file_put_contents($tmp, wp_json_encode($this->data));
		@rename($tmp, $this->path('state.json'));
		self::heartbeat($this->id);
	}

	/**
	 * Adds a log line (kept short).
	 *
	 * @param string $line Message.
	 * @return void
	 */
	public function log($line)
	{
		$this->data['log'][] = gmdate('H:i:s') . ' ' . $line;
		if (count($this->data['log']) > 200) {
			$this->data['log'] = array_slice($this->data['log'], -200);
		}
	}

	/**
	 * Exclusive lock so two requests never work on the same job.
	 *
	 * @return bool
	 */
	public function lock()
	{
		$this->lock = @fopen($this->path('lock'), 'c');
		if (! $this->lock) {
			return false;
		}
		if (! flock($this->lock, LOCK_EX | LOCK_NB)) {
			fclose($this->lock);
			$this->lock = null;
			return false;
		}
		return true;
	}

	/**
	 * Releases the lock.
	 *
	 * @return void
	 */
	public function unlock()
	{
		if ($this->lock) {
			flock($this->lock, LOCK_UN);
			fclose($this->lock);
			$this->lock = null;
		}
	}

	/**
	 * Deletes the job folder and clears the active marker.
	 *
	 * @return void
	 */
	public function destroy()
	{
		$this->unlock();
		Shiftbox_Storage::rrmdir($this->path());
		$active = self::active();
		if ($active && $active['id'] === $this->id) {
			@unlink(self::active_file());
		}
	}

	/**
	 * Path of the active-job marker.
	 *
	 * @return string
	 */
	private static function active_file()
	{
		return Shiftbox_Storage::dir() . '/active.json';
	}

	/**
	 * Marks a job as active.
	 *
	 * @param string $id   Id.
	 * @param string $type Type.
	 * @return void
	 */
	private static function set_active($id, $type)
	{
		self::write_active(
			array(
				'id'   => $id,
				'type' => $type,
				'beat' => time(),
			)
		);
	}

	/**
	 * Refreshes the heartbeat.
	 *
	 * @param string $id Id.
	 * @return void
	 */
	private static function heartbeat($id)
	{
		$active = self::active(true);
		if ($active && $active['id'] === $id) {
			$active['beat'] = time();
			self::write_active($active);
		}
	}

	/**
	 * Writes the active-job marker atomically, so a reader never sees a half-written file.
	 *
	 * @param array $data Marker data.
	 * @return void
	 */
	private static function write_active(array $data)
	{
		$tmp = self::active_file() . '.tmp';
		file_put_contents($tmp, wp_json_encode($data));
		@rename($tmp, self::active_file());
	}

	/**
	 * The running job, if any. Jobs silent for 30 minutes count as abandoned.
	 *
	 * @param bool $include_stale Return even if stale.
	 * @return array|null id, type, beat.
	 */
	public static function active($include_stale = false)
	{
		$file = self::active_file();
		if (! is_file($file)) {
			return null;
		}
		$data = wp_json_file_decode($file, array('associative' => true));
		if (! is_array($data) || empty($data['id'])) {
			return null;
		}
		if (! $include_stale && (time() - (int) $data['beat']) > 1800) {
			return null;
		}
		if (! is_dir(Shiftbox_Storage::jobs_dir() . '/' . $data['id'])) {
			@unlink($file);
			return null;
		}
		return $data;
	}

	/**
	 * Removes job folders older than a day that are not active.
	 *
	 * @return void
	 */
	public static function cleanup_stale()
	{
		$active = self::active(true);
		foreach ((array) glob(Shiftbox_Storage::jobs_dir() . '/*', GLOB_ONLYDIR) as $dir) {
			$id = basename($dir);
			if ($active && $active['id'] === $id && (time() - (int) $active['beat']) < 1800) {
				continue;
			}
			if (time() - (int) @filemtime($dir . '/state.json') > DAY_IN_SECONDS) {
				Shiftbox_Storage::rrmdir($dir);
			}
		}
		foreach ((array) glob(Shiftbox_Storage::uploads_dir() . '/*') as $file) {
			if (is_file($file) && 'index.php' !== basename($file) && '.htaccess' !== basename($file) && 'web.config' !== basename($file) && time() - (int) @filemtime($file) > 2 * DAY_IN_SECONDS) {
				@unlink($file);
			}
		}
	}
}