<?php declare(strict_types=1);
/*
 * This file is part of Aplus Framework Session Library.
 *
 * (c) Natan Felles <natanfelles@gmail.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Framework\Session\SaveHandlers;

use Framework\Log\LogLevel;
use Framework\Session\SaveHandler;
use LogicException;
use RuntimeException;
use SensitiveParameter;

/**
 * Class FilesHandler.
 *
 * @package session
 */
class FilesHandler extends SaveHandler
{
    /**
     * @var resource|null
     */
    protected $stream;

    /**
     * Prepare configurations to be used by the FilesHandler.
     *
     * @param array<string,mixed> $config Custom configs
     *
     * The custom configs are:
     *
     * ```php
     * $configs = [
     *     // The directory path where the session files will be saved
     *     'directory' => '',
     *     // A custom directory name inside the `directory` path
     *     'prefix' => '',
     *     // Match IP?
     *     'match_ip' => false,
     *     // Match User-Agent?
     *     'match_ua' => false,
     * ];
     * ```
     */
    protected function prepareConfig(#[SensitiveParameter] array $config) : void
    {
        $this->config = \array_replace([
            'prefix' => '',
            'directory' => '',
            'match_ip' => false,
            'match_ua' => false,
        ], $config);
        if (empty($this->config['directory'])) {
            throw new LogicException('Session config has not a directory');
        }
        $this->config['directory'] = \rtrim(
            $this->config['directory'],
            \DIRECTORY_SEPARATOR
        ) . \DIRECTORY_SEPARATOR;
        if (!\is_dir($this->config['directory'])) {
            throw new LogicException(
                'Session config directory does not exist: ' . $this->config['directory']
            );
        }
        if ($this->config['prefix']) {
            $dirname = $this->config['directory'] . $this->config['prefix'] . \DIRECTORY_SEPARATOR;
            if (!\is_dir($dirname) && !\mkdir($dirname, 0700) && !\is_dir($dirname)) {
                throw new RuntimeException(
                    "Session prefix directory '{$dirname}' was not created",
                );
            }
            $this->config['directory'] = $dirname;
        }
    }

    /**
     * Get the filename, using the optional
     * match IP and match User-Agent configs.
     *
     * @param string $id The session id
     *
     * @return string The final filename
     */
    protected function getFilename(string $id) : string
    {
        $filename = $this->config['directory'] . $id[0] . $id[1] . \DIRECTORY_SEPARATOR . $id;
        return $filename . $this->getKeySuffix();
    }

    public function open($path, $name) : bool
    {
        return true;
    }

    public function read($id) : string
    {
        if ($this->stream !== null) {
            \rewind($this->stream);
            return $this->readData();
        }
        $filename = $this->getFilename($id);
        $dirname = \dirname($filename);
        if (!\is_dir($dirname) && !\mkdir($dirname, 0700) && !\is_dir($dirname)) {
            throw new RuntimeException(
                "Session subdirectory '{$dirname}' was not created",
            );
        }
        $this->sessionExists = \is_file($filename);
        if (!$this->lock($filename)) {
            return '';
        }
        if (!isset($this->sessionId)) {
            $this->sessionId = $id;
        }
        if (!$this->sessionExists) {
            \chmod($filename, 0600);
            $this->setFingerprint('');
            return '';
        }
        return $this->readData();
    }

    protected function readData() : string
    {
        $data = '';
        while (!\feof($this->stream)) {
            $data .= \fread($this->stream, 1024);
        }
        $this->setFingerprint($data);
        return $data;
    }

    public function write($id, $data) : bool
    {
        if (!isset($this->stream)) {
            return false;
        }
        if ($id !== $this->sessionId) {
            $this->sessionId = $id;
        }
        if ($this->hasSameFingerprint($data)) {
            return !$this->sessionExists || \touch($this->getFilename($id));
        }
        if ($this->sessionExists) {
            \ftruncate($this->stream, 0);
            \rewind($this->stream);
        }
        if ($data !== '') {
            $written = \fwrite($this->stream, $data);
            if ($written === false) {
                $this->log('Session (files): Unable to write data');
                return false;
            }
        }
        $this->setFingerprint($data);
        return true;
    }

    public function updateTimestamp($id, $data) : bool
    {
        $filename = $this->getFilename($id);
        return \is_file($filename)
            ? \touch($filename)
            : \fwrite($this->stream, $data) !== false;
    }

    public function close() : bool
    {
        if (!\is_resource($this->stream)) {
            return true;
        }
        $this->unlock();
        $this->sessionExists = false;
        return true;
    }

    public function destroy($id) : bool
    {
        $this->close();
        \clearstatcache();
        $filename = $this->getFilename($id);
        return !\is_file($filename) || \unlink($filename);
    }

    public function gc($max_lifetime) : false | int
    {
        $dirHandle = \opendir($this->config['directory']);
        if ($dirHandle === false) {
            $this->log(
                "Session (files): Garbage Collector could not open directory '{$this->config['directory']}'",
                LogLevel::DEBUG
            );
            return false;
        }
        $gcCount = 0;
        $max_lifetime = \time() - $max_lifetime;
        while (($filename = \readdir($dirHandle)) !== false) {
            if ($filename !== '.'
                && $filename !== '..'
                && \is_dir($this->config['directory'] . $filename)
            ) {
                $gcCount += $this->gcSubdir(
                    $this->config['directory'] . $filename,
                    $max_lifetime
                );
            }
        }
        \closedir($dirHandle);
        return $gcCount;
    }

    protected function gcSubdir(string $directory, int $maxMtime) : int
    {
        $gcCount = 0;
        $dirHandle = \opendir($directory);
        if ($dirHandle === false) {
            return $gcCount;
        }
        while (($filename = \readdir($dirHandle)) !== false) {
            $filename = $directory . \DIRECTORY_SEPARATOR . $filename;
            if (\is_dir($filename)) {
                continue;
            }
            $mtime = \filemtime($filename);
            if (($mtime < $maxMtime) && \unlink($filename)) {
                $gcCount++;
            }
        }
        \closedir($dirHandle);
        if (\count((array) \scandir($directory)) === 2) {
            \rmdir($directory);
        }
        return $gcCount;
    }

    protected function lock(string $id) : bool
    {
        $stream = \fopen($id, 'c+b');
        if ($stream === false) {
            return false;
        }
        if (\flock($stream, \LOCK_EX) === false) {
            $this->log("Session (files): Error while trying to lock '{$id}'");
            \fclose($stream);
            return false;
        }
        $this->stream = $stream;
        return true;
    }

    protected function unlock() : bool
    {
        if ($this->stream === null) {
            return true;
        }
        $unlocked = \flock($this->stream, \LOCK_UN);
        if ($unlocked === false) {
            $this->log('Session (files): Error while trying to unlock ' . $this->getFilename($this->sessionId));
        }
        \fclose($this->stream);
        $this->stream = null;
        return true;
    }
}