/*****************************************************************
 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 ****************************************************************/

package org.apache.cayenne.dba;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.util.Util;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

import java.io.InputStream;
import java.net.URL;
import java.sql.Types;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * TypesHandler provides JDBC-RDBMS types mapping. Loads types info from an XML
 * file.
 * 
 */
public class TypesHandler {

	private static Map<URL, TypesHandler> handlerMap = new HashMap<>();

	protected Map<Integer, String[]> typesMap;

	/**
	 * @since 1.1
	 */
	public static TypesHandler getHandler(URL typesConfig) {
		synchronized (handlerMap) {
			TypesHandler handler = handlerMap.get(typesConfig);

			if (handler == null) {
				handler = new TypesHandler(typesConfig);
				handlerMap.put(typesConfig, handler);
			}

			return handler;
		}
	}

	/**
	 * Creates new TypesHandler loading configuration info from the XML file
	 * specified as <code>typesConfigPath</code> parameter.
	 * 
	 * @since 1.1
	 */
	public TypesHandler(URL typesConfig) {

		try (InputStream in = typesConfig.openStream();) {
			XMLReader parser = Util.createXmlReader();
			TypesParseHandler ph = new TypesParseHandler();
			parser.setContentHandler(ph);
			parser.setErrorHandler(ph);
			parser.parse(new InputSource(in));

			typesMap = ph.getTypes();
		} catch (Exception ex) {
			throw new CayenneRuntimeException("Error creating TypesHandler '" + typesConfig + "'.", ex);
		}
	}

	public String[] externalTypesForJdbcType(int type) {
		return typesMap.get(type);
	}

	/**
	 * Helper class to load types data from XML.
	 */
	final class TypesParseHandler extends DefaultHandler {
		private static final String JDBC_TYPE_TAG = "jdbc-type";
		private static final String DB_TYPE_TAG = "db-type";
		private static final String NAME_ATTR = "name";

		private Map<Integer, String[]> types = new HashMap<>();
		private List<String> currentTypes = new ArrayList<>();
		private int currentType = TypesMapping.NOT_DEFINED;

		public Map<Integer, String[]> getTypes() {
			return types;
		}

		@Override
		public void startElement(String namespaceURI, String localName, String qName, Attributes atts)
				throws SAXException {
			if (JDBC_TYPE_TAG.equals(localName)) {
				currentTypes.clear();
				String strType = atts.getValue("", NAME_ATTR);

				// convert to Types int value
				try {
					currentType = Types.class.getDeclaredField(strType).getInt(null);
				} catch (Exception ex) {
					currentType = TypesMapping.NOT_DEFINED;
				}
			} else if (DB_TYPE_TAG.equals(localName)) {
				currentTypes.add(atts.getValue("", NAME_ATTR));
			}
		}

		@Override
		public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
			if (JDBC_TYPE_TAG.equals(localName) && currentType != TypesMapping.NOT_DEFINED) {
				String[] typesAsArray = new String[currentTypes.size()];
				types.put(Integer.valueOf(currentType), currentTypes.toArray(typesAsArray));
			}
		}
	}
}