/**

 * 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();

	}

}