/*
 * 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.sling.jcr.jackrabbit.accessmanager.post;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.jcr.Item;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.jcr.security.AccessControlEntry;
import javax.jcr.security.AccessControlList;
import javax.jcr.security.AccessControlManager;
import javax.servlet.Servlet;

import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.resource.ResourceNotFoundException;
import org.apache.sling.jcr.base.util.AccessControlUtil;
import org.apache.sling.jcr.jackrabbit.accessmanager.DeleteAces;
import org.apache.sling.servlets.post.Modification;
import org.apache.sling.servlets.post.PostResponse;
import org.apache.sling.servlets.post.PostResponseCreator;
import org.apache.sling.servlets.post.SlingPostConstants;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.component.annotations.ReferenceCardinality;
import org.osgi.service.component.annotations.ReferencePolicy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <p>
 * Sling Post Servlet implementation for deleting the ACE for a set of principals on a JCR
 * resource.
 * </p>
 * <h2>Rest Service Description</h2>
 * <p>
 * Delete a set of Ace's from a node, the node is identified as a resource by the request
 * url &gt;resource&lt;.deleteAce.html
 * </p>
 * <h4>Methods</h4>
 * <ul>
 * <li>POST</li>
 * </ul>
 * <h4>Post Parameters</h4>
 * <dl>
 * <dt>:applyTo</dt>
 * <dd>An array of ace principal names to delete. Note the principal name is the primary
 * key of the Ace in the Acl</dd>
 * </dl>
 *
 * <h4>Response</h4>
 * <dl>
 * <dt>200</dt>
 * <dd>Success.</dd>
 * <dt>404</dt>
 * <dd>The resource was not found.</dd>
 * <dt>500</dt>
 * <dd>Failure. HTML explains the failure.</dd>
 * </dl>
 */

@Component(service = {Servlet.class, DeleteAces.class},
    property= {
    		"sling.servlet.resourceTypes=sling/servlet/default",
    		"sling.servlet.methods=POST",
    		"sling.servlet.selectors=deleteAce"
    })
public class DeleteAcesServlet extends AbstractAccessPostServlet implements DeleteAces {
	private static final long serialVersionUID = 3784866802938282971L;

	/**
     * default log
     */
    private final Logger log = LoggerFactory.getLogger(getClass());

    /**
     * Overridden since the @Reference annotation is not inherited from the super method
     *  
	 * @see org.apache.sling.jackrabbit.usermanager.impl.post.AbstractPostServlet#bindPostResponseCreator(org.apache.sling.servlets.post.PostResponseCreator, java.util.Map)
	 */
	@Override
    @Reference(service = PostResponseCreator.class,
	    cardinality = ReferenceCardinality.MULTIPLE,
	    policy = ReferencePolicy.DYNAMIC)
	protected void bindPostResponseCreator(PostResponseCreator creator, Map<String, Object> properties) {
		super.bindPostResponseCreator(creator, properties);
	}
	
	/* (non-Javadoc)
	 * @see org.apache.sling.jackrabbit.usermanager.impl.post.AbstractPostServlet#unbindPostResponseCreator(org.apache.sling.servlets.post.PostResponseCreator, java.util.Map)
	 */
	@Override
	protected void unbindPostResponseCreator(PostResponseCreator creator, Map<String, Object> properties) {
		super.unbindPostResponseCreator(creator, properties);
	}
    
	
	/* (non-Javadoc)
	 * @see org.apache.sling.jackrabbit.accessmanager.post.AbstractAccessPostServlet#handleOperation(org.apache.sling.api.SlingHttpServletRequest, org.apache.sling.servlets.post.PostResponse, java.util.List)
	 */
	@Override
	protected void handleOperation(SlingHttpServletRequest request,
			PostResponse htmlResponse, List<Modification> changes)
			throws RepositoryException {

		Session session = request.getResourceResolver().adaptTo(Session.class);
    	String resourcePath = request.getResource().getPath();
        String[] applyTo = request.getParameterValues(SlingPostConstants.RP_APPLY_TO);
        deleteAces(session, resourcePath, applyTo);
	}

	/* (non-Javadoc)
	 * @see org.apache.sling.jcr.jackrabbit.accessmanager.DeleteAces#deleteAces(javax.jcr.Session, java.lang.String, java.lang.String[])
	 */
	public void deleteAces(Session jcrSession, String resourcePath,
			String[] principalNamesToDelete) throws RepositoryException {

        if (principalNamesToDelete == null) {
			throw new RepositoryException("principalIds were not sumitted.");
        } else {
    		if (jcrSession == null) {
    			throw new RepositoryException("JCR Session not found");
    		}

        	if (resourcePath == null) {
    			throw new ResourceNotFoundException("Resource path was not supplied.");
        	}

    		Item item = jcrSession.getItem(resourcePath);
    		if (item != null) {
    			resourcePath = item.getPath();
    		} else {
    			throw new ResourceNotFoundException("Resource is not a JCR Node");
    		}

    		//load the principalIds array into a set for quick lookup below
			Set<String> pidSet = new HashSet<String>();
			pidSet.addAll(Arrays.asList(principalNamesToDelete));

			try {
				AccessControlManager accessControlManager = AccessControlUtil.getAccessControlManager(jcrSession);
				AccessControlList updatedAcl = getAccessControlListOrNull(accessControlManager, resourcePath, false);
				// if there is no AccessControlList, then there is nothing to be deleted
				if (updatedAcl == null) {
					// log the warning about principals where no ACE was found
					for (String pid : pidSet) {
						log.warn("No AccessControlEntry was found to be deleted for principal: " + pid);
					}
				} else {
					//keep track of the existing Aces for the target principal
					AccessControlEntry[] accessControlEntries = updatedAcl.getAccessControlEntries();
					List<AccessControlEntry> oldAces = new ArrayList<AccessControlEntry>();
					for (AccessControlEntry ace : accessControlEntries) {
						if (pidSet.contains(ace.getPrincipal().getName())) {
							oldAces.add(ace);
						}
					}

					// track which of the submitted principals had an ACE removed
					Set<String> removedPidSet = new HashSet<>();
					
					//remove the old aces
					if (!oldAces.isEmpty()) {
						for (AccessControlEntry ace : oldAces) {
							updatedAcl.removeAccessControlEntry(ace);
					
							// remove from the candidate set
							removedPidSet.add(ace.getPrincipal().getName());
						}
					}

					// log the warning about principals where no ACE was found
					for (String pid : pidSet) {
						if (!removedPidSet.contains(pid)) {
							log.warn("No AccessControlEntry was found to be deleted for principal: " + pid);
						}
					}

					//apply the changed policy
					accessControlManager.setPolicy(resourcePath, updatedAcl);
				}
			} catch (RepositoryException re) {
				throw new RepositoryException("Failed to delete access control.", re);
			}
        }
	}
	
}