/**

  * 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.io.IOException;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.io.Reader;

 import java.io.UnsupportedEncodingException;

 import java.net.MalformedURLException;

 import java.net.URL;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 import org.xml.sax.EntityResolver;

 import org.xml.sax.InputSource;

 import org.xml.sax.SAXException;

 /**

  *

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

  */

 public class AltInputSource extends InputSource {

 	private final EntityResolver entityResolver;

 	private final InputSource originalSource;

 	private static final Logger log = Logger.getLogger(AltInputSource.class.getName());

 	public AltInputSource(EntityResolver entityResolver, InputSource originalSource) {

 		this.entityResolver = entityResolver;

 		this.originalSource = originalSource;

 	}

 	@Override

 	public InputStream getByteStream() {

 		InputStream originalStream = originalSource.getByteStream();

 		if (originalStream == null) {

 			InputSource source = originalSource;

 			if (entityResolver != null) {

 				try {

 					InputSource resolvedSource = entityResolver.resolveEntity(originalSource.getSystemId(), originalSource.getSystemId());

 					if (resolvedSource != null) {

 						source = resolvedSource;

 					}

 				} catch (IOException | SAXException e) {

 					log.log(Level.WARNING, "Error while resolving InputSource – publicId: " + originalSource.getPublicId() + " systemId: " + originalSource.getSystemId(), e);

 				}

 			}

 			InputStream resolvedStream = source.getByteStream();

 			if (resolvedStream == null) {

 				try {

 					URL url = new URL(source.getSystemId());

 					return url.openStream();

 				} catch (MalformedURLException e) {

 					log.log(Level.WARNING, "Invalid SystemId URL syntax: " + originalSource.getSystemId(), e);

 					return null;

 				} catch (IOException e) {

 					log.log(Level.WARNING, "Unable to open stream for systemId: " + originalSource.getSystemId(), e);

 					return null;

 				}

 			} else {

 				return resolvedStream;

 			}

 		} else {

 			return originalStream;

 		}

 	}

 	@Override

 	public Reader getCharacterStream() {

 		Reader originalStream = originalSource.getCharacterStream();

 		if (originalStream == null) {

 			String encoding = getEncoding();

 			if (encoding == null) {

 				return new InputStreamReader(getByteStream());

 			} else {

 				try {

 					return new InputStreamReader(getByteStream(), encoding);

 				} catch (UnsupportedEncodingException e) {

 					log.log(Level.WARNING, "Invalid encoding: " + encoding, e);

 					return null;

 				}

 			}

 		} else {

 			return originalStream;

 		}

 	}

 	@Override

 	public String getEncoding() {

 		return originalSource.getEncoding();

 	}

 	@Override

 	public String getPublicId() {

 		return originalSource.getPublicId();

 	}

 	@Override

 	public String getSystemId() {

 		return originalSource.getSystemId();

 	}

 	@Override

 	public String toString() {

 		return "AltInputSource: systemId=" + getSystemId() + " publicId=" + getPublicId();

 	}

 }