<?php
/**
 * Class DirScanner
 * TODO: 兼容windows系统目录结构
 */

Class DirScanner {
    private $nginxSecureOn = false;                     //Nginx防盗链开启状态
    private $nginxSecret = 'foo=bar';                   //Nginx防盗链密钥
    private $userIp = '127.0.0.1';                      //用户IP地址
    private $nginxSecureTimeout = 1800;                 //Nginx防盗链有效期，单位：秒
    private $nginxSecureLinkMd5Pattern = '{secure_link_expires}{uri}{remote_addr} {secret}';         //Nginx防盗链MD5加密方式
    private $allowReadContentFileExtensions = [     //允许读取文件内容的文件类型
        'txt',
        'md',
        'url',
    ];
    private $fields = [                             //私有属性字段名和说明
        'directory' => '目录名',
        'filename' => '文件名',
        'realpath' => '完整路径',
        'path' => '相对网址',
        'extension' => '文件后缀',
        'fstat' => '资源状态',                      //同php方法fstat: https://www.php.net/manual/en/function.fstat.php
        'content' => 'MD文件内容',
        'shortcut' => 'URL快捷方式',

        'description' => '描述',
        'keywords' => '关键词',
        'snapshot' => '快照图片',
    ];
    private $rootDir;                               //当前扫描的根目录
    private $scanningDirLevel = 0;                  //当前扫描的目录深度
    private $scanStartTime = 0;                     //扫描开始时间，单位：秒
    private $scanResults = [];                      //目录扫描结果


    protected $supportFileExtensions = [            //支持的文件类型
        'txt',     //纯文本
        'md',      //纯文本
        'url',     //快捷方式
        'jpg',     //图片
        'png',     //图片
        'gif',     //图片
        'ico',     //图标
        'mp4',     //视频
        'ts',      //视频
        'm3u8',    //视频
    ];
    protected $maxReadFilesize = [                  //默认每种文件读取内容最大大小
        'txt' => 100*1024,          //纯文本
        'md' => 5*1024*1024,        //纯文本
        'url' => 20*1024,           //快捷方式
        'jpg' => 500*1024,          //图片
        'png' => 500*1024,          //图片
        'gif' => 500*1024,          //图片
        'ico' => 50*1024,           //图标
        'mp4' => 100*1024*1024,     //视频
        'ts' => 10*1024*1024,       //视频
        'm3u8' => 10*1024*1024,     //视频
    ];
    protected $securedFileExtensions = [            //开启Nginx防盗链的文件类型
        'jpg',     //图片
        'png',     //图片
        'gif',     //图片
        'ico',     //图标
        'mp4',     //视频
        'ts',      //视频
        'm3u8',    //视频
    ];

    public $scanTimeCost = 0;                       //上一次目录扫描耗时，单位：毫秒


    //解析描述文件内容
    private function parseDescriptionFiles($realpath) {
        $pathinfo = pathinfo($realpath);
        $field = preg_replace('/^.+_/', '', $pathinfo['filename']);
        $content = file_get_contents($realpath);
        $data = [];
        $data[$field] = $content;

        return $data;
    }

    //解析快捷方式文件内容
    private function parseShortCuts($realpath, $filename) {
        $content = file_get_contents($realpath);
        if (empty($content) || !preg_match('/\[InternetShortcut\]/i', $content)) {return false;}

        preg_match('/URL=(\S+)/i', $content, $matches);
        if (empty($matches) || empty($matches[1])) {
            return false;
        }

        return [
            'name' => $filename,
            'url' => $matches[1],
        ];
    }

    //根据文件路径生成唯一编号
    private function getId($realpath) {
        return !empty($realpath) ? md5($realpath) : '';
    }

    //判断Nginx防盗链MD5加密方式字符串是否合格
    private function isNginxSecureLinkMd5PatternValid($pattern) {
        $valid = true;

        $fieldsNeeded = [
                '{secure_link_expires}',
                '{uri}',
                '{remote_addr}',
                '{secret}',
            ];
        foreach($fieldsNeeded as $needle) {
            if (strstr($pattern, $needle) === false) {
                $valid = false;
                break;
            }
        }

        return $valid;
    }

    //根据路径生成目录数组
    private function getDirData($realpath, $files) {
        $id = $this->getId($realpath);
        $data = [
            'id' => $id,
            'directory' => basename($realpath),
            'realpath' => $realpath,
            'path' => $this->getDirPath($id),
            'files' => $files,
        ];

        //try to merge description data
        if (!empty($files[$id])) {
            $data = array_merge($data, $files[$id]);
            unset($files[$id]);
            $data['files'] = $files;
        }

        return $data;
    }

    //根据路径生成文件数组，兼容URL文件
    private function getFileData($realpath, $dirLevel) {
        $id = $this->getId($realpath);
        $fp = fopen($realpath, 'r');
        $fstat = fstat($fp);
        fclose($fp);
        $pathinfo = pathinfo($realpath);
        $extension = strtolower($pathinfo['extension']);
        $data = [
            'id' => $id,
            'filename' => $pathinfo['filename'],
            'extension' => $extension,
            'fstat' => [
                'size' => $fstat['size'],
                'atime' => $fstat['atime'],
                'mtime' => $fstat['mtime'],
                'ctime' => $fstat['ctime'],
            ],
            'realpath' => $realpath,
            'path' => $this->getFilePath( $id, $this->getDirectoryName($pathinfo['dirname'], $dirLevel), $pathinfo['filename'], $extension ),
        ];

        if ($extension == 'url') {
            $data['shortcut'] = $this->parseShortCuts($realpath, $pathinfo['filename']);
        }

        return $data;
    }

    //根据路径和根目录获取当前扫描的目录深度
    private function getScanningLevel($rootDir, $dirname) {
        $level = 0;

        if ($dirname == $rootDir) {
            $level = 1;
        }else {
            $dirname = preg_replace('/\/$/', '', $dirname);
            $dirs = explode('/', str_replace($rootDir, '', $dirname));
            $level = count($dirs);
        }

        return $level;
    }

    //根据路径和当前扫描深度获取目录名
    private function getDirectoryName($dirname, $dirLevel) {
        if ($dirLevel <= 0) {return basename($dirname);}
        $dirname = preg_replace('/\/$/', '', $dirname);
        $dirname = preg_replace('/^\//', '', $dirname);
        $names = explode('/', $dirname);
        if ($dirLevel >= count($names)) {return $dirname;}
        return implode('/', array_splice($names, -$dirLevel));
    }

    //合并描述文件内容到md文件或者目录数据
    private function mergeDescriptionData($realpath) {
        $data = [];
        $ext = $this->parseDescriptionFiles($realpath);

        //try to find the md file
        $targetFile = preg_replace('/_?[a-z0-9]+\.txt$/iU', '.md', $realpath);
        if (file_exists($targetFile)) {
            $fileId = $this->getId($targetFile);
            if (empty($this->scanResults[$fileId])) {
                $ext['id'] = $fileId;
                $this->scanResults[$fileId] = $ext;
                $data = $ext;
            }else {
                $data = $this->scanResults[$fileId];
                $data = array_merge($data, $ext);
                $this->scanResults[$fileId] = $data;
            }
        }else {
            //try to merge to the parent directory
            $targetDir = preg_replace('/\/[a-z0-9]+\.txt$/i', '', $realpath);
            if (is_dir($targetDir)) {
                $dirId = $this->getId($targetDir);
                if (empty($this->scanResults[$dirId])) {
                    $ext['id'] = $dirId;
                    $this->scanResults[$dirId] = $ext;
                    $data = $ext;
                }else {
                    $data = $this->scanResults[$dirId];
                    $data = array_merge($data, $ext);
                    $this->scanResults[$dirId] = $data;
                }
            }
        }

        return $data;
    }


    //根据文件生成防盗链网址
    //参考：https://nginx.org/en/docs/http/ngx_http_secure_link_module.html#secure_link
    //防盗链参数名：md5, expires
    protected function getSecureLink($path) {
        $expires = time() + $this->nginxSecureTimeout;
        $originStr = str_replace([
                '{secure_link_expires}',
                '{uri}',
                '{remote_addr}',
                '{secret}',
            ], [
                $expires,
                $path,
                $this->userIp,
                $this->nginxSecret,
            ], $this->nginxSecureLinkMd5Pattern);

        $md5 = base64_encode( md5($originStr, true) );
        $md5 = strtr($md5, '+/', '-_');
        $md5 = str_replace('=', '', $md5);

        return "{$path}?md5={$md5}&expires={$expires}";
    }

    //根据文件生成相对路径
    protected function getFilePath($id, $directory, $filename, $extension) {
        if (empty($directory)) {
            $directory = '/';
        }
        if (!preg_match('/\/$/', $directory)) {
            $directory .= '/';
        }
        if (!preg_match('/^\//', $directory)) {
            $directory = "/{$directory}";
        }

        $extensionPathMap = [                  //默认每种文件读取内容最大大小
            'txt' => '',
            'md' => '/view/',
            'url' => '/link/',
            'm3u8' => '/m3u8/',
            'jpg' => "{$directory}{$filename}.{$extension}",
            'png' => "{$directory}{$filename}.{$extension}",
            'gif' => "{$directory}{$filename}.{$extension}",
            'ico' => "{$directory}{$filename}.{$extension}",
            'mp4' => "{$directory}{$filename}.{$extension}",
            'ts' => "{$directory}{$filename}.{$extension}",
        ];

        $path = isset($extensionPathMap[$extension]) ? $extensionPathMap[$extension] : '';

        if (!empty($path) && in_array($extension, ['md', 'url', 'm3u8'])) {
            if ($this->nginxSecureOn && $extension == 'm3u8') {
                $path = $this->getSecureLink($path);
                $path = "{$path}&id={$id}";
            }else {
                $path = "{$path}?id={$id}";
            }
        }else if (!empty($path) && $this->nginxSecureOn) {
            $path = $this->getSecureLink($path);
        }

        return $path;
    }

    //根据目录生成相对路径
    protected function getDirPath($id) {
        return "/list/?id={$id}";
    }


    //设置Nginx防盗链开启或关闭，以及密钥、加密方式、超时时长
    public function setNginxSecure($secureOn, $secret = '', $userIp = '', $pattern = '', $timeout = 0) {
        $status = false;
        if (is_string($secureOn) && strtolower($secureOn) == 'on') {
            $status = true;
        }else if (is_string($secureOn) && strtolower($secureOn) == 'off') {
            $status = false;
        }else if ((bool)$secureOn == true) {
            $status = true;
        }
        $this->nginxSecureOn = $status;

        if (!empty($secret) && is_string($secret)) {
            $this->nginxSecret = $secret;
        }

        if (!empty($userIp) && is_string($userIp)) {
            $this->userIp = $userIp;
        }

        if (!empty($pattern) && is_string($pattern)) {
            if ($this->isNginxSecureLinkMd5PatternValid($pattern) == false) {
                throw new Exception("Invalid Nginx secure link md5 pattern: {$pattern}", 500);
            }
            $this->nginxSecureLinkMd5Pattern = $pattern;
        }

        if ((int)$timeout > 0) {
            $this->nginxSecureTimeout = (int)$timeout;
        }
    }

    //设置Nginx防盗链密钥
    public function setNginxSecret($secret) {
        if (!empty($secret) && is_string($secret)) {
            $this->nginxSecret = $secret;
        }
    }

    //获取Nginx防盗链密钥
    public function getNginxSecret() {
        return $this->nginxSecret;
    }

    //设置Nginx防盗链密钥
    public function setUserIp($userIp) {
        if (!empty($userIp) && is_string($userIp)) {
            $this->userIp = $userIp;
        }
    }

    //获取Nginx防盗链密钥
    public function getUserIp() {
        return $this->userIp;
    }

    //设置Nginx防盗链MD5加密方式
    /**
     * Nginx防盗链MD5加密方式参考下面网址中的示例，
     * 将Nginx的变量替换$符号为英文大括号；
     * 
     * 示例：
     * ```
     * {secure_link_expires}{uri}{remote_addr} {secret}
     * ```
     * Nginx文档参考：http://nginx.org/en/docs/http/ngx_http_secure_link_module.html#secure_link_md5
     */
    public function setNginxSecureLinkMd5Pattern($pattern) {
        if (!empty($pattern) && is_string($pattern)) {
            if ($this->isNginxSecureLinkMd5PatternValid($pattern) == false) {
                throw new Exception("Invalid Nginx secure link md5 pattern: {$pattern}", 500);
            }
            $this->nginxSecureLinkMd5Pattern = $pattern;
        }
    }

    //获取Nginx防盗链MD5加密方式
    public function getNginxSecureLinkMd5Pattern() {
        return $this->nginxSecureLinkMd5Pattern;
    }

    //设置Nginx防盗链超时时长，单位：秒
    public function setNginxSecureTimeout($timeout) {
        if ((int)$timeout > 0) {
            $this->nginxSecureTimeout = (int)$timeout;
        }
    }

    //获取Nginx防盗链超时时长，单位：秒
    public function getNginxSecureTimeout() {
        return $this->nginxSecureTimeout;
    }

    //获取是否开启防盗链
    public function isSecureOn() {
        return $this->nginxSecureOn;
    }

    //扫描目录获取目录和文件列表，支持指定目录扫描深度（目录级数）
    public function scan($dir, $levels = 3) {
        if (empty($this->scanStartTime)) {
            $this->scanStartTime = microtime(true);
        }

        $tree = array();

        $ignore_files = array('.', '..');
        if (is_dir($dir)) {
            if (!preg_match('/\/$/', $dir)) {$dir .= '/';}
            if (empty($this->rootDir)) {
                $this->rootDir = $dir;
            }
            $this->scanningDirLevel = $this->getScanningLevel($this->rootDir, $dir);
            $nextLevels = $levels - $this->scanningDirLevel;

            $files = scandir($dir);
            foreach($files as $file) {
                if (in_array($file, $ignore_files)) {continue;}

                $branch = [];
                $realpath = realpath("{$dir}{$file}");
                if (is_dir($realpath)) {
                    $files = [];
                    if ($nextLevels > 0) {
                        $files = $this->scan($realpath, $nextLevels);
                        if (!empty($files)) {
                            foreach($files as $file) {
                                $this->scanResults[$file['id']] = $file;
                            }
                        }
                    }

                    $branch = $this->getDirData($realpath, $files);
                }else {
                    $pathinfo = pathinfo($realpath);
                    $extension = strtolower($pathinfo['extension']);
                    if ( in_array($extension, $this->supportFileExtensions) ) {
                        if ($extension != 'txt') {
                            $branch = $this->getFileData($realpath, $this->scanningDirLevel);
                        }else {
                            //把描述文件内容合并到被描述的目录或md文件数据中
                            $branch = $this->mergeDescriptionData($realpath);
                        }
                    }
                }

                if (!empty($branch)) {
                    $this->scanResults[$branch['id']] = $branch;
                    $tree[$branch['id']] = $branch;
                }
            }
        }

        $time = microtime(true);
        $this->scanTimeCost = $this->scanStartTime > 0 ? ceil( ($time - $this->scanStartTime)*1000 ) : 0;

        return $tree;
    }

    //获取扫描结果
    public function getScanResults() {
        return $this->scanResults;
    }

}