package org.apache.maven.continuum.buildqueue.evaluator;

/*
 * 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.
 */

import org.apache.maven.continuum.buildqueue.BuildProjectTask;
import org.apache.maven.continuum.project.ContinuumProjectState;
import org.codehaus.plexus.logging.AbstractLogEnabled;
import org.codehaus.plexus.taskqueue.TaskViabilityEvaluator;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * @author <a href="mailto:trygvis@inamo.no">Trygve Laugst&oslash;l</a>
 * @version $Id$
 */
public class BuildProjectTaskViabilityEvaluator
    extends AbstractLogEnabled
    implements TaskViabilityEvaluator
{
    /**
     * @plexus.configuration
     */
    private long requiredBuildInterval;

    // ----------------------------------------------------------------------
    // TaskViabilityEvaluator Implementation
    // ----------------------------------------------------------------------

    /**
     * Removes duplicate tasks from the list. A duplicate task is one with the same
     * build definition and that's scheduled within the required build interval.
     * <p/>
     * <p/>
     * &forall; <sub>t1, t2 &isin; tasks</sub> [ t1 &ne; t2 &and; t2.buildDefinition = t2.buildDefinition]:
     * if ( t2.timestamp - t1.timestamp < requiredBuildInterval ) remove( t2 ).
     * </p>
     *
     * @param tasks A list of queued tasks to evaluate
     * @return a list of tasks with duplicates removed
     */
    public Collection<BuildProjectTask> evaluate( Collection tasks )
    {
        // ----------------------------------------------------------------------
        // This code makes a Map with Lists with one list per project. For each
        // task in the list it puts it in the list for the project that's
        // requested for a build. Then all each of the lists with tasks is
        // checked for validity and a list of tasks to remove is returned.
        // ----------------------------------------------------------------------

        Map<Integer, List<BuildProjectTask>> projects = new HashMap<Integer, List<BuildProjectTask>>();

        for ( BuildProjectTask task : (Collection<BuildProjectTask>) tasks )
        {
            Integer key = new Integer( task.getProjectId() );

            List<BuildProjectTask> projectTasks = (List<BuildProjectTask>) projects.get( key );

            if ( projectTasks == null )
            {
                projectTasks = new ArrayList<BuildProjectTask>();

                projects.put( key, projectTasks );
            }

            projectTasks.add( task );
        }

        List<BuildProjectTask> toBeRemoved = new ArrayList<BuildProjectTask>();

        for ( Iterator it = projects.values().iterator(); it.hasNext(); )
        {
            toBeRemoved.addAll( checkTasks( (List) it.next() ) );
        }

        return toBeRemoved;
    }

    // ----------------------------------------------------------------------
    //
    // ----------------------------------------------------------------------

    private List<BuildProjectTask> checkTasks( List<BuildProjectTask> list )
    {
        List<BuildProjectTask> toBeRemoved = new ArrayList<BuildProjectTask>();

        for ( BuildProjectTask buildProjectTask : list )
        {
            for ( BuildProjectTask task : list )
            {
                // check if it's the same task
                if ( buildProjectTask == task ||
                    buildProjectTask.getBuildDefinitionId() != task.getBuildDefinitionId() )
                {
                    continue;
                }

                // ----------------------------------------------------------------------
                // If this build is forces, don't remove it
                // ----------------------------------------------------------------------

                if ( task.getTrigger() == ContinuumProjectState.TRIGGER_FORCED )
                {
                    continue;
                }

                // ----------------------------------------------------------------------
                //
                // ----------------------------------------------------------------------

                long interval = task.getTimestamp() - buildProjectTask.getTimestamp();

                if ( interval < requiredBuildInterval )
                {
                    toBeRemoved.add( buildProjectTask );
                }
            }
        }

        return toBeRemoved;
    }
}