001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.ioc.services.cron;
016
017import org.apache.tapestry5.ioc.internal.services.cron.CronExpression;
018
019import java.text.ParseException;
020import java.util.Date;
021import java.util.TimeZone;
022
023public class CronSchedule implements Schedule
024{
025    private CronExpression cron;
026
027    public CronSchedule(String cronExpression)
028    {
029        this(cronExpression, TimeZone.getDefault());
030    }
031
032    public CronSchedule(String cronExpression, TimeZone timeZone)
033    {
034        try
035        {
036            this.cron = new CronExpression(cronExpression);
037            this.cron.setTimeZone(timeZone);
038        } catch (ParseException e)
039        {
040            throw new RuntimeException(e);
041        }
042    }
043
044    @Override
045    public long firstExecution()
046    {
047        return getNextValidTimeAfterNow();
048    }
049
050    @Override
051    public long nextExecution(long previousExecution)
052    {
053        return getNextValidTimeAfterNow();
054    }
055
056    private long getNextValidTimeAfterNow()
057    {
058        final Date time = cron.getNextValidTimeAfter(new Date());
059
060        return time == null ? 0 : time.getTime();
061    }
062}