public class ValidatorBootstrapTest {

	private static final String VALIDATION_XML_FILE = "META-INF/validation.xml";

	@Test
	public void assertValidatorInstanceCanBeCreatedWithValidationXml() {
		Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
		assertNotNull( validator );
	}

	@Test
	public void assertLookaheadParsingWorksWithStax() throws Exception {
		InputStream in = null;
		try {
			in = getValidationXmlInputStream();
			if ( !in.markSupported() ) {
				in = new BufferedInputStream( in );
			}
			String actualVersion = getSchemaVersion( in );
			assertEquals( "1.1", actualVersion );
		}
		finally {
			if ( in != null ) {
				in.close();
			}
		}
	}

	@Test
	public void assertBufferedInputstreamSupportsMarkAndReset() throws Exception {
		String s = "Say it twice";
		byte bytes[] = s.getBytes();
		assertEquals( "Unexpected number of bytes", 12, bytes.length );

		ByteArrayInputStream in = new ByteArrayInputStream( bytes );
		StringBuilder actual = new StringBuilder();

		int read = 0;
		int c;
		boolean reset = false;
		try (BufferedInputStream f = new BufferedInputStream( in )) {
			f.mark( 1024 * 1024 );
			while ( read < bytes.length ) {
				c = f.read();
				actual.append( (char) c );
				read++;
				if ( read == 12 ) {
					if ( reset ) {
						break;
					}
					else {
						f.reset();
						read = 0;
						reset = true;
					}
				}
			}
		}


		assertEquals( "Say it twiceSay it twice", actual.toString() );
	}

	private String getSchemaVersion(InputStream xmlInputStream) throws Exception {
		xmlInputStream.mark( 1024 * 1024 );

		try {
			XMLEventReader xmlEventReader = createXmlEventReader( xmlInputStream );
			StartElement rootElement = getRootElement( xmlEventReader );

			return getVersionValue( rootElement );
		}
		finally {
			xmlInputStream.reset();
		}
	}
	
	private XMLEventReader createXmlEventReader(InputStream xmlStream) throws XMLStreamException {
		return XMLInputFactory.newInstance().createXMLEventReader( xmlStream );
	}

	private StartElement getRootElement(XMLEventReader xmlEventReader) throws XMLStreamException {
		while ( xmlEventReader.hasNext() ) {
			XMLEvent nextEvent = xmlEventReader.nextEvent();
			if ( nextEvent.isStartElement() ) {
				return nextEvent.asStartElement();
			}
		}

		return null;
	}

	private String getVersionValue(StartElement startElement) {
		if ( startElement == null ) {
			return null;
		}

		Attribute versionAttribute = startElement.getAttributeByName( new QName( "version" ) );
		return versionAttribute.getValue();
	}

	private InputStream getValidationXmlInputStream() {
		ClassLoader loader = this.getClass().getClassLoader();
		return loader.getResourceAsStream( VALIDATION_XML_FILE );
	}
}