class ManifestDocument

class ManifestDocument {
    public const XMLNS = 'https://phar.io/xml/manifest/1.0';
    
    /** @var DOMDocument */
    private $dom;
    public static function fromFile(string $filename) : ManifestDocument {
        if (!is_file($filename)) {
            throw new ManifestDocumentException(sprintf('File "%s" not found', $filename));
        }
        return self::fromString(file_get_contents($filename));
    }
    public static function fromString(string $xmlString) : ManifestDocument {
        $prev = libxml_use_internal_errors(true);
        libxml_clear_errors();
        try {
            $dom = new DOMDocument();
            $dom->loadXML($xmlString);
            $errors = libxml_get_errors();
            libxml_use_internal_errors($prev);
        } catch (Throwable $t) {
            throw new ManifestDocumentException($t->getMessage(), 0, $t);
        }
        if (count($errors) !== 0) {
            throw new ManifestDocumentLoadingException($errors);
        }
        return new self($dom);
    }
    private function __construct(DOMDocument $dom) {
        $this->ensureCorrectDocumentType($dom);
        $this->dom = $dom;
    }
    public function getContainsElement() : ContainsElement {
        return new ContainsElement($this->fetchElementByName('contains'));
    }
    public function getCopyrightElement() : CopyrightElement {
        return new CopyrightElement($this->fetchElementByName('copyright'));
    }
    public function getRequiresElement() : RequiresElement {
        return new RequiresElement($this->fetchElementByName('requires'));
    }
    public function hasBundlesElement() : bool {
        return $this->dom
            ->getElementsByTagNameNS(self::XMLNS, 'bundles')->length === 1;
    }
    public function getBundlesElement() : BundlesElement {
        return new BundlesElement($this->fetchElementByName('bundles'));
    }
    private function ensureCorrectDocumentType(DOMDocument $dom) : void {
        $root = $dom->documentElement;
        if ($root->localName !== 'phar' || $root->namespaceURI !== self::XMLNS) {
            throw new ManifestDocumentException('Not a phar.io manifest document');
        }
    }
    private function fetchElementByName(string $elementName) : DOMElement {
        $element = $this->dom
            ->getElementsByTagNameNS(self::XMLNS, $elementName)
            ->item(0);
        if (!$element instanceof DOMElement) {
            throw new ManifestDocumentException(sprintf('Element %s missing', $elementName));
        }
        return $element;
    }

}