/**
 * This file Copyright (c) 2003-2012 Magnolia International
 * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
 *
 *
 * This file is dual-licensed under both the Magnolia
 * Network Agreement and the GNU General Public License.
 * You may elect to use one or the other of these licenses.
 *
 * This file is distributed in the hope that it will be
 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
 * Redistribution, except as permitted by whichever of the GPL
 * or MNA you select, is prohibited.
 *
 * 1. For the GPL license (GPL), you can redistribute and/or
 * modify this file under the terms of the GNU General
 * Public License, Version 3, as published by the Free Software
 * Foundation.  You should have received a copy of the GNU
 * General Public License, Version 3 along with this program;
 * if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 2. For the Magnolia Network Agreement (MNA), this file
 * and the accompanying materials are made available under the
 * terms of the MNA which accompanies this distribution, and
 * is available at http://www.magnolia-cms.com/mna.html
 *
 * Any modifications to this file must keep this entire header
 * intact.
 *
 */
package info.magnolia.module.delta;

import info.magnolia.cms.filters.FilterManager;
import info.magnolia.jcr.util.NodeUtil;
import info.magnolia.module.InstallContext;

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

import javax.jcr.Node;
import javax.jcr.NodeIterator;
import javax.jcr.RepositoryException;

/**
 * Orders a filter <strong>after</strong> a given set of other filters. The filter is placed directly after the last of
 * other filters. The other filters can be required or optional, if a required filter isn't present this task will do
 * nothing and report a warning. If all other filters are optional and none are present this task does nothing. Does not
 * take nested filters into account.
 *
 * @version $Id$
 * @see OrderFilterBeforeTask
 */
public class FilterOrderingTask extends AbstractRepositoryTask {

    private final String filterToBeOrderedName;
    private final List<String> requiredFilters;
    private final List<String> optionalFilters;

    /**
     * @param filterName name of filter to be placed after the required filters.
     * @param requiredFiltersBefore an array of filter names that must appear <strong>before</strong> the filter specified as filterName.
     */
    public FilterOrderingTask(String filterName, String[] requiredFiltersBefore) {
        this(filterName, requiredFiltersBefore, new String[] {});
    }

    public FilterOrderingTask(String filterName, String[] requiredFiltersBefore, String[] optionalFiltersBefore) {
        this(filterName, "Orders the " + filterName + " filter in the filter chain.", requiredFiltersBefore, optionalFiltersBefore);
    }

    public FilterOrderingTask(String filterName, String description, String[] requiredFiltersBefore) {
        this(filterName, description, requiredFiltersBefore, new String[] {});
    }

    public FilterOrderingTask(String filterName, String description, String[] requiredFiltersBefore, String[] optionalFiltersBefore) {
        super("Setup " + filterName + " filter", description);
        this.filterToBeOrderedName = filterName;
        this.requiredFilters = new ArrayList<String>(Arrays.asList(requiredFiltersBefore));
        this.optionalFilters = new ArrayList<String>(Arrays.asList(optionalFiltersBefore));
    }

    @Override
    protected void doExecute(InstallContext ctx) throws RepositoryException, TaskExecutionException {
        final Node filtersParent = ctx.getConfigJCRSession().getNode(FilterManager.SERVER_FILTERS);

        // assert filter exists
        if (!filtersParent.hasNode(filterToBeOrderedName)) {
            throw new TaskExecutionException("Filter with name " + filterToBeOrderedName + " can't be found.");
        }

        if (!requiredFilters.isEmpty() && !hasNodes(filtersParent, requiredFilters)) {
            ctx.warn("Could not sort filter " + filterToBeOrderedName + ". It should be positioned after " + requiredFilters);
            return;
        }

        Set<String> combinedFilterNames = new HashSet<String>();
        combinedFilterNames.addAll(requiredFilters);
        combinedFilterNames.addAll(optionalFilters);

        orderAfterSiblings(filtersParent.getNode(filterToBeOrderedName), combinedFilterNames);
    }

    private void orderAfterSiblings(Node node, Set<String> siblingNames) throws RepositoryException {
        Node lastMatch = getLastChild(node.getParent(), siblingNames);
        if (lastMatch != null) {
            NodeUtil.orderAfter(node, lastMatch.getName());
        }
    }

    private Node getLastChild(Node parent, Collection<String> childNames) throws RepositoryException {
        Node lastMatch = null;
        NodeIterator nodes = parent.getNodes();
        while (nodes.hasNext()) {
            Node child = nodes.nextNode();
            if (childNames.contains(child.getName())) {
                lastMatch = child;
            }
        }
        return lastMatch;
    }

    private boolean hasNodes(Node node, Collection<String> childNames) throws RepositoryException {
        for (String childName : childNames) {
            if (!node.hasNode(childName)) {
                return false;
            }
        }
        return true;
    }
}