/*
 * 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.ranger.authorization.hadoop;


import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hdfs.server.namenode.INodeAttributeProvider;
import org.apache.hadoop.hdfs.server.namenode.INodeAttributes;
import org.apache.ranger.plugin.classloader.RangerPluginClassLoader;

public class RangerHdfsAuthorizer extends INodeAttributeProvider {
	private static final Log LOG  = LogFactory.getLog(RangerHdfsAuthorizer.class);

	private static final String   RANGER_PLUGIN_TYPE                      = "hdfs";
	private static final String   RANGER_HDFS_AUTHORIZER_IMPL_CLASSNAME   = "org.apache.ranger.authorization.hadoop.RangerHdfsAuthorizer";

	private INodeAttributeProvider 	rangerHdfsAuthorizerImpl 		= null;
	private static RangerPluginClassLoader rangerPluginClassLoader  = null;
	
	public RangerHdfsAuthorizer() {
		if(LOG.isDebugEnabled()) {
			LOG.debug("==> RangerHdfsAuthorizer.RangerHdfsAuthorizer()");
		}

		this.init();

		if(LOG.isDebugEnabled()) {
			LOG.debug("<== RangerHdfsAuthorizer.RangerHdfsAuthorizer()");
		}
	}

	public void init(){
		if(LOG.isDebugEnabled()) {
			LOG.debug("==> RangerHdfsAuthorizer.init()");
		}

		try {
			
			rangerPluginClassLoader = RangerPluginClassLoader.getInstance(RANGER_PLUGIN_TYPE, this.getClass());
			
			@SuppressWarnings("unchecked")
			Class<INodeAttributeProvider> cls = (Class<INodeAttributeProvider>) Class.forName(RANGER_HDFS_AUTHORIZER_IMPL_CLASSNAME, true, rangerPluginClassLoader);

			activatePluginClassLoader();

			rangerHdfsAuthorizerImpl = cls.newInstance();
		} catch (Exception e) {
			// check what need to be done
			LOG.error("Error Enabling RangerHdfsPlugin", e);
		} finally {
			deactivatePluginClassLoader();
		}

		if(LOG.isDebugEnabled()) {
			LOG.debug("<== RangerHdfsAuthorizer.init()");
		}
	}

	@Override
	public void start() {
		if(LOG.isDebugEnabled()) {
			LOG.debug("==> RangerHdfsAuthorizer.start()");
		}

		try {
			activatePluginClassLoader();

			rangerHdfsAuthorizerImpl.start();
		} finally {
			deactivatePluginClassLoader();
		}

		if(LOG.isDebugEnabled()) {
			LOG.debug("<== RangerHdfsAuthorizer.start()");
		}
	}

	@Override
	public void stop() {
		if(LOG.isDebugEnabled()) {
			LOG.debug("==> RangerHdfsAuthorizer.stop()");
		}

		try {
			activatePluginClassLoader();

			rangerHdfsAuthorizerImpl.stop();
		} finally {
			deactivatePluginClassLoader();
		}

		if(LOG.isDebugEnabled()) {
			LOG.debug("<== RangerHdfsAuthorizer.stop()");
		}
	}

	@Override
	public INodeAttributes getAttributes(String fullPath, INodeAttributes inode) {
		if(LOG.isDebugEnabled()) {
			LOG.debug("==> RangerHdfsAuthorizer.getAttributes(" + fullPath + ")");
		}

		INodeAttributes ret = null;

		try {
			activatePluginClassLoader();

			ret = rangerHdfsAuthorizerImpl.getAttributes(fullPath,inode); // return default attributes
		} finally {
			deactivatePluginClassLoader();
		}

		if(LOG.isDebugEnabled()) {
			LOG.debug("<== RangerHdfsAuthorizer.getAttributes(" + fullPath + "): " + ret);
		}

		return ret;
	}

	@Override
	public INodeAttributes getAttributes(String[] pathElements, INodeAttributes inode) {
		if(LOG.isDebugEnabled()) {
			LOG.debug("==> RangerHdfsAuthorizer.getAttributes(pathElementsCount=" + (pathElements == null ? 0 : pathElements.length) + ")");
		}

		INodeAttributes ret = null;

		try {
			activatePluginClassLoader();

			ret = rangerHdfsAuthorizerImpl.getAttributes(pathElements,inode);
		} finally {
			deactivatePluginClassLoader();
		}

		if(LOG.isDebugEnabled()) {
			LOG.debug("<== RangerHdfsAuthorizer.getAttributes(pathElementsCount=" + (pathElements == null ? 0 : pathElements.length) + "): " + ret);
		}

		return ret;
	}

	@Override
	public AccessControlEnforcer getExternalAccessControlEnforcer(AccessControlEnforcer defaultEnforcer) {
		if(LOG.isDebugEnabled()) {
			LOG.debug("==> RangerHdfsAuthorizer.getExternalAccessControlEnforcer()");
		}

		AccessControlEnforcer ret = null;

		ret = rangerHdfsAuthorizerImpl.getExternalAccessControlEnforcer(defaultEnforcer);

		if(LOG.isDebugEnabled()) {
			LOG.debug("<== RangerHdfsAuthorizer.getExternalAccessControlEnforcer()");
		}

		return ret;
	}

	private void activatePluginClassLoader() {
		if(rangerPluginClassLoader != null) {
			rangerPluginClassLoader.activate();
		}
	}

	private void deactivatePluginClassLoader() {
		if(rangerPluginClassLoader != null) {
			rangerPluginClassLoader.deactivate();
		}
	}
}