/**

 * Alt2XML

 * Copyright © 2014 František Kučera (frantovo.cz)

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. If not, see <http://www.gnu.org/licenses/>.

 */

package cz.frantovo.alt2xml;

import java.util.Deque;

import java.util.LinkedList;

import java.util.ServiceLoader;

import javax.xml.parsers.FactoryConfigurationError;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.parsers.SAXParser;

import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Parser;

import org.xml.sax.SAXException;

import org.xml.sax.SAXNotRecognizedException;

import org.xml.sax.SAXNotSupportedException;

import org.xml.sax.XMLReader;

/**

 *

 * @author Ing. František Kučera (frantovo.cz)

 */

public class ParserFactory extends SAXParserFactory implements ReaderFinder {

	private final Deque<Alt2XmlReaderFactory> readerFactories = new LinkedList();

	/**

	 * @see #DEFAULT_FACTORY_PROPERTY

	 */

	private SAXParserFactory fallbackFactory;

	/**

	 * System property which contains SAXParserFactory class name for XML.

	 * Will be used as fallback if no alternative factory matches systemId to be parsed.

	 */

	public static final String DEFAULT_FACTORY_PROPERTY = "cz.frantovo.alt2xml.fallback.javax.xml.parsers.SAXParserFactory";

	public ParserFactory() {

		super();

		for (Alt2XmlReaderFactory f : ServiceLoader.load(Alt2XmlReaderFactory.class)) {

			readerFactories.add(f);

		}

		readerFactories.add(new FallbackReaderFactory());

	}

	/**

	 * @return factory to be used for XML documents (default/fallback)

	 * @throws FactoryConfigurationError if fallback factory is the same one as this – avoid

	 * infinite recursion.

	 */

	public SAXParserFactory getFallbackFactory() {

		if (fallbackFactory == null) {

			String className = System.getProperty(DEFAULT_FACTORY_PROPERTY);

			if (className == null) {

				fallbackFactory = SAXParserFactory.newInstance();

			} else {

				fallbackFactory = SAXParserFactory.newInstance(className, null);

			}

		}

		if (fallbackFactory.getClass().equals(getClass())) {

			throw new FactoryConfigurationError("Fallback factory is the same class as this one – avoid infinite recursion: " + getClass());

		} else {

			return fallbackFactory;

		}

	}

	public void setFallbackFactory(SAXParserFactory fallbackFactory) {

		this.fallbackFactory = fallbackFactory;

	}

	private class FallbackReaderFactory implements Alt2XmlReaderFactory {

		@Override

		public boolean canRead(String systemId) {

			return true;

		}

		@Override

		public XMLReader getReader() throws SAXException {

			try {

				return getFallbackFactory().newSAXParser().getXMLReader();

			} catch (ParserConfigurationException e) {

				throw new SAXException("Unable to instantiate the fallback factory.", e);

			}

		}

	}

	@Override

	public XMLReader findReader(String systemId) throws SAXException {

		for (Alt2XmlReaderFactory f : readerFactories) {

			if (f.canRead(systemId)) {

				return f.getReader();

			}

		}

		throw new SAXException("Iterated over " + readerFactories.size() + " and was unable to find XMLReader for SystemId: " + systemId);

	}

	@Override

	public SAXParser newSAXParser() throws ParserConfigurationException, SAXException {

		return new AltSAXParser(new SuperReader(this));

	}

	/**

	 * TODO: feature for disabling default SAXParserFactory

	 */

	@Override

	public void setFeature(String name, boolean value) throws ParserConfigurationException, SAXNotRecognizedException, SAXNotSupportedException {

		throw new SAXNotSupportedException("Zatím není podporováno.");

	}

	@Override

	public boolean getFeature(String name) throws ParserConfigurationException, SAXNotRecognizedException, SAXNotSupportedException {

		throw new SAXNotSupportedException("Zatím není podporováno.");

	}

	private static class AltSAXParser extends SAXParser {

		private XMLReader xmlReader;

		public AltSAXParser(XMLReader xmlReader) {

			this.xmlReader = xmlReader;

		}

		@Override

		@Deprecated

		public Parser getParser() throws SAXException {

			throw new SAXException("Není podporováno.");

		}

		@Override

		public XMLReader getXMLReader() throws SAXException {

			return xmlReader;

		}

		@Override

		public boolean isNamespaceAware() {

			return true;

		}

		@Override

		public boolean isValidating() {

			return false;

		}

		@Override

		public void setProperty(String name, Object value) throws SAXNotRecognizedException, SAXNotSupportedException {

			xmlReader.setProperty(name, value);

		}

		@Override

		public Object getProperty(String name) throws SAXNotRecognizedException, SAXNotSupportedException {

			return xmlReader.getProperty(name);

		}

	}

}