class Reader

class Reader {
    
    /**
     * @var string
     */
    private $fileName;
    
    /**
     * Mime-type in order to use zlib, bzip2 or no compression.
     * In case ext-fileinfo is not present only the relevant types
     * 'application/x-gzip' and 'application/x-bzip2' are assigned
     * to this class property.
     *
     * @var string
     */
    private $fileType;
    
    /**
     * @param string $fileName
     */
    public function __construct($fileName) {
        if (strpos($fileName, '://') !== false) {
            throw new ReaderException('File name must not contain stream prefix', 1539623708);
        }
        $this->fileName = $fileName;
        $this->fileType = $this->determineFileType();
    }
    
    /**
     * @return Container
     */
    public function resolveContainer() {
        $data = $this->extractData($this->resolveStream() . $this->fileName);
        if ($data['stubContent'] === null) {
            throw new ReaderException('Cannot resolve stub', 1547807881);
        }
        if ($data['manifestContent'] === null || $data['manifestLength'] === null) {
            throw new ReaderException('Cannot resolve manifest', 1547807882);
        }
        if (strlen($data['manifestContent']) < $data['manifestLength']) {
            throw new ReaderException(sprintf('Exected manifest length %d, got %d', strlen($data['manifestContent']), $data['manifestLength']), 1547807883);
        }
        return new Container(Stub::fromContent($data['stubContent']), Manifest::fromContent($data['manifestContent']));
    }
    
    /**
     * @param string $fileName e.g. '/path/file.phar' or 'compress.zlib:///path/file.phar'
     * @return array
     */
    private function extractData($fileName) {
        $stubContent = null;
        $manifestContent = null;
        $manifestLength = null;
        $resource = fopen($fileName, 'r');
        if (!is_resource($resource)) {
            throw new ReaderException(sprintf('Resource %s could not be opened', $fileName), 1547902055);
        }
        while (!feof($resource)) {
            $line = fgets($resource);
            // stop reading file when manifest can be extracted
            if ($manifestLength !== null && $manifestContent !== null && strlen($manifestContent) >= $manifestLength) {
                break;
            }
            $manifestPosition = strpos($line, '__HALT_COMPILER();');
            // first line contains start of manifest
            if ($stubContent === null && $manifestContent === null && $manifestPosition !== false) {
                $stubContent = substr($line, 0, $manifestPosition - 1);
                $manifestContent = preg_replace('#^.*__HALT_COMPILER\\(\\);(?>[ \\n]\\?>(?>\\r\\n|\\n)?)?#', '', $line);
                $manifestLength = $this->resolveManifestLength($manifestContent);
                // line contains start of stub
            }
            elseif ($stubContent === null) {
                $stubContent = $line;
                // line contains start of manifest
            }
            elseif ($manifestContent === null && $manifestPosition !== false) {
                $manifestContent = preg_replace('#^.*__HALT_COMPILER\\(\\);(?>[ \\n]\\?>(?>\\r\\n|\\n)?)?#', '', $line);
                $manifestLength = $this->resolveManifestLength($manifestContent);
                // manifest has been started (thus is cannot be stub anymore), add content
            }
            elseif ($manifestContent !== null) {
                $manifestContent .= $line;
                $manifestLength = $this->resolveManifestLength($manifestContent);
                // stub has been started (thus cannot be manifest here, yet), add content
            }
            elseif ($stubContent !== null) {
                $stubContent .= $line;
            }
        }
        fclose($resource);
        return array(
            'stubContent' => $stubContent,
            'manifestContent' => $manifestContent,
            'manifestLength' => $manifestLength,
        );
    }
    
    /**
     * Resolves stream in order to handle compressed Phar archives.
     *
     * @return string
     */
    private function resolveStream() {
        if ($this->fileType === 'application/x-gzip' || $this->fileType === 'application/gzip') {
            return 'compress.zlib://';
        }
        elseif ($this->fileType === 'application/x-bzip2') {
            return 'compress.bzip2://';
        }
        return '';
    }
    
    /**
     * @return string
     */
    private function determineFileType() {
        if (class_exists('\\finfo')) {
            $fileInfo = new \finfo();
            return $fileInfo->file($this->fileName, FILEINFO_MIME_TYPE);
        }
        return $this->determineFileTypeByHeader();
    }
    
    /**
     * In case ext-fileinfo is not present only the relevant types
     * 'application/x-gzip' and 'application/x-bzip2' are resolved.
     *
     * @return string
     */
    private function determineFileTypeByHeader() {
        $resource = fopen($this->fileName, 'r');
        if (!is_resource($resource)) {
            throw new ReaderException(sprintf('Resource %s could not be opened', $this->fileName), 1557753055);
        }
        $header = fgets($resource, 4);
        fclose($resource);
        $mimeType = '';
        if (strpos($header, "BZh") === 0) {
            $mimeType = 'application/x-bzip2';
        }
        elseif (strpos($header, "\x1f\x8b") === 0) {
            $mimeType = 'application/x-gzip';
        }
        return $mimeType;
    }
    
    /**
     * @param string $content
     * @return int|null
     */
    private function resolveManifestLength($content) {
        if (strlen($content) < 4) {
            return null;
        }
        return static::resolveFourByteLittleEndian($content, 0);
    }
    
    /**
     * @param string $content
     * @param int $start
     * @return int
     */
    public static function resolveFourByteLittleEndian($content, $start) {
        $payload = substr($content, $start, 4);
        if (!is_string($payload)) {
            throw new ReaderException(sprintf('Cannot resolve value at offset %d', $start), 1539614260);
        }
        $value = unpack('V', $payload);
        if (!isset($value[1])) {
            throw new ReaderException(sprintf('Cannot resolve value at offset %d', $start), 1539614261);
        }
        return $value[1];
    }
    
    /**
     * @param string $content
     * @param int $start
     * @return int
     */
    public static function resolveTwoByteBigEndian($content, $start) {
        $payload = substr($content, $start, 2);
        if (!is_string($payload)) {
            throw new ReaderException(sprintf('Cannot resolve value at offset %d', $start), 1539614263);
        }
        $value = unpack('n', $payload);
        if (!isset($value[1])) {
            throw new ReaderException(sprintf('Cannot resolve value at offset %d', $start), 1539614264);
        }
        return $value[1];
    }

}