OpenSearchXMLReader.java

/*
 * Copyright (C) 2010-2011 Geometer Plus <contact@geometerplus.com>
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

package org.geometerplus.fbreader.network.opds;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.geometerplus.zlibrary.core.constants.XMLNamespaces;
import org.geometerplus.zlibrary.core.constants.MimeTypes;
import org.geometerplus.zlibrary.core.util.ZLNetworkUtil;
import org.geometerplus.zlibrary.core.xml.ZLStringMap;
import org.geometerplus.zlibrary.core.xml.ZLXMLReaderAdapter;

class OpenSearchXMLReader extends ZLXMLReaderAdapter {
	private final List<OpenSearchDescription> myDescriptions;

	private final String myBaseURL;

	public OpenSearchXMLReader(String baseUrl, List<OpenSearchDescription> descriptions) {
		myDescriptions = descriptions;
		myBaseURL = baseUrl;
	}

	private String myOpenSearchNamespaceId;

	@Override
	public boolean processNamespaces() {
		return true;
	}

	private static String intern(String str) {
		if (str == null || str.length() == 0) {
			return null;
		}
		return str.intern();
	}

	@Override
	public void namespaceMapChangedHandler(Map<String, String> namespaces) {
		myOpenSearchNamespaceId = null;

		for (Map.Entry<String,String> entry : namespaces.entrySet()) {
			final String value = entry.getValue();
			if (value == XMLNamespaces.OpenSearch) {
				myOpenSearchNamespaceId = intern(entry.getKey());
			}
		}
	}

	private int parseInt(String value) {
		if (value == null || value.length() == 0) {
			return -1;
		}
		try {
			return Integer.valueOf(value);
		} catch (NumberFormatException e) {
			return -1;
		}
	}

	private static final int START = 0;
	private static final int DESCRIPTION = 1;

	private static final String TAG_DESCRIPTION = "OpenSearchDescription";
	private static final String TAG_URL = "Url";

	private int myState = START;

	@Override
	public boolean startElementHandler(String tag, ZLStringMap attributes) {
		final int index = tag.indexOf(':');
		final String tagPrefix;
		if (index != -1) {
			tagPrefix = tag.substring(0, index).intern();
			tag = tag.substring(index + 1).intern();
		} else {
			tagPrefix = null;
			tag = tag.intern();
		}

		switch (myState) {
		case START:
			if (tagPrefix == myOpenSearchNamespaceId && tag == TAG_DESCRIPTION) {
				myState = DESCRIPTION;
			}
			break;
		case DESCRIPTION:
			if (tagPrefix == myOpenSearchNamespaceId && tag == TAG_URL) {
				final String type = attributes.getValue("type");
				final String rel = attributes.getValue("rel");
				if (type == MimeTypes.MIME_APP_ATOM
						&& (rel == null || rel == "results")) {
					final String template = ZLNetworkUtil.url(myBaseURL, attributes.getValue("template"));
					final int indexOffset = parseInt(attributes.getValue("indexOffset"));
					final int pageOffset = parseInt(attributes.getValue("pageOffset"));
					final OpenSearchDescription descr =
						new OpenSearchDescription(template, indexOffset, pageOffset);
					if (descr.isValid()) {
						myDescriptions.add(descr);
					}
				}
			}
			break;
		}

		return false;
	}

	@Override
	public boolean endElementHandler(String tag) {
		final int index = tag.indexOf(':');
		final String tagPrefix;
		if (index != -1) {
			tagPrefix = tag.substring(0, index).intern();
			tag = tag.substring(index + 1).intern();
		} else {
			tagPrefix = null;
			tag = tag.intern();
		}

		switch (myState) {
		case DESCRIPTION:
			if (tagPrefix == myOpenSearchNamespaceId && tag == TAG_DESCRIPTION) {
				myState = START;
			}
			break;
		}
		return false;
	}
}