/*
    * Copyright (C) 2007-2012 Argeo GmbH
    *
    * Licensed 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.argeo.jcr.proxy;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.URL;
  
  import javax.jcr.Binary;
  import javax.jcr.Node;
  import javax.jcr.Property;
  import javax.jcr.Repository;
  import javax.jcr.RepositoryException;
  import javax.jcr.Session;
  import javax.jcr.nodetype.NodeType;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.argeo.jcr.ArgeoJcrException;
  import org.argeo.jcr.JcrUtils;
  
  /** Base class for URL based proxys. */
  public abstract class AbstractUrlProxy implements ResourceProxy {
  	private final static Log log = LogFactory.getLog(AbstractUrlProxy.class);
  
  	private Repository jcrRepository;
  	private Session jcrAdminSession;
  	private String proxyWorkspace = "proxy";
  
  	protected abstract Node retrieve(Session session, String path);
  
  	void init() {
  		try {
  			jcrAdminSession = JcrUtils.loginOrCreateWorkspace(jcrRepository, proxyWorkspace);
  			beforeInitSessionSave(jcrAdminSession);
  			if (jcrAdminSession.hasPendingChanges())
  				jcrAdminSession.save();
  		} catch (Exception e) {
  			JcrUtils.discardQuietly(jcrAdminSession);
  			throw new ArgeoJcrException("Cannot initialize Maven proxy", e);
  		}
  	}
  
  	/**
  	 * Called before the (admin) session is saved at the end of the initialization.
  	 * Does nothing by default, to be overridden.
  	 */
  	protected void beforeInitSessionSave(Session session) throws RepositoryException {
  	}
  
  	void destroy() {
  		JcrUtils.logoutQuietly(jcrAdminSession);
  	}
  
  	/**
  	 * Called before the (admin) session is logged out when resources are released.
  	 * Does nothing by default, to be overridden.
  	 */
  	protected void beforeDestroySessionLogout() throws RepositoryException {
  	}
  
  	public Node proxy(String path) {
  		// we open a JCR session with client credentials in order not to use the
  		// admin session in multiple thread or make it a bottleneck.
  		Node nodeAdmin = null;
  		Node nodeClient = null;
  		Session clientSession = null;
  		try {
  			clientSession = jcrRepository.login(proxyWorkspace);
  			if (!clientSession.itemExists(path) || shouldUpdate(clientSession, path)) {
  				nodeAdmin = retrieveAndSave(path);
  				if (nodeAdmin != null)
  					nodeClient = clientSession.getNode(path);
  			} else
  				nodeClient = clientSession.getNode(path);
  			return nodeClient;
  		} catch (RepositoryException e) {
  			throw new ArgeoJcrException("Cannot proxy " + path, e);
  		} finally {
  			if (nodeClient == null)
  				JcrUtils.logoutQuietly(clientSession);
  		}
  	}
  
  	protected synchronized Node retrieveAndSave(String path) {
  		try {
 			Node node = retrieve(jcrAdminSession, path);
 			if (node == null)
 				return null;
 			jcrAdminSession.save();
 			return node;
 		} catch (RepositoryException e) {
 			JcrUtils.discardQuietly(jcrAdminSession);
 			throw new ArgeoJcrException("Cannot retrieve and save " + path, e);
 		} finally {
 			notifyAll();
 		}
 	}
 
 	/** Session is not saved */
 	protected synchronized Node proxyUrl(Session session, String remoteUrl, String path) throws RepositoryException {
 		Node node = null;
 		if (session.itemExists(path)) {
 			// throw new ArgeoJcrException("Node " + path + " already exists");
 		}
 		try (InputStream in = new URL(remoteUrl).openStream()) {
 			// URL u = new URL(remoteUrl);
 			// in = u.openStream();
 			node = importFile(session, path, in);
 		} catch (IOException e) {
 			if (log.isDebugEnabled()) {
 				log.debug("Cannot read " + remoteUrl + ", skipping... " + e.getMessage());
 				// log.trace("Cannot read because of ", e);
 			}
 			JcrUtils.discardQuietly(session);
 			// } finally {
 			// IOUtils.closeQuietly(in);
 		}
 		return node;
 	}
 
 	protected synchronized Node importFile(Session session, String path, InputStream in) throws RepositoryException {
 		Binary binary = null;
 		try {
 			Node content = null;
 			Node node = null;
 			if (!session.itemExists(path)) {
 				node = JcrUtils.mkdirs(session, path, NodeType.NT_FILE, NodeType.NT_FOLDER, false);
 				content = node.addNode(Node.JCR_CONTENT, NodeType.NT_UNSTRUCTURED);
 			} else {
 				node = session.getNode(path);
 				content = node.getNode(Node.JCR_CONTENT);
 			}
 			binary = session.getValueFactory().createBinary(in);
 			content.setProperty(Property.JCR_DATA, binary);
 			JcrUtils.updateLastModifiedAndParents(node, null);
 			return node;
 		} finally {
 			JcrUtils.closeQuietly(binary);
 		}
 	}
 
 	/** Whether the file should be updated. */
 	protected Boolean shouldUpdate(Session clientSession, String nodePath) {
 		return false;
 	}
 
 	public void setJcrRepository(Repository jcrRepository) {
 		this.jcrRepository = jcrRepository;
 	}
 
 	public void setProxyWorkspace(String localWorkspace) {
 		this.proxyWorkspace = localWorkspace;
 	}
 
 }