# CronSchedule.java

    /*
     * Copyright (c) 2010-2012, Paul Merlin. All Rights Reserved.
     * Copyright (c) 2012, Niclas Hedhman. All Rights Reserved.
     *
     * 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.qi4j.library.scheduler.schedule.cron;

    import org.qi4j.api.mixin.Mixins;
    import org.qi4j.api.property.Immutable;
    import org.qi4j.api.property.Property;
    import org.qi4j.library.scheduler.schedule.Schedule;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;

    @Mixins( CronSchedule.CronScheduleMixin.class )
    public interface CronSchedule
        extends Schedule
    {
        /**
         * The Cron expression indicating when the Schedule is to be run.
         * The Schedule can NOT be changed once it is set. If this is needed, delete this Schedule and attach the Task
         * to a new Schedule.
         *
         * @return The cron expression that will be used on {@link org.qi4j.api.unitofwork.UnitOfWork} completion to compute next run
         */
        @CronExpression
        @Immutable
        Property<String> cronExpression();

        abstract class CronScheduleMixin
            implements CronSchedule
        {
            private static final Logger LOGGER = LoggerFactory.getLogger( Schedule.class );
            private boolean running;

            @Override
            public void taskStarting()
            {
                running = true;
            }

            @Override
            public void taskCompletedSuccessfully()
            {
                running = false;
            }

            @Override
            public void taskCompletedWithException( RuntimeException ex )
            {
                running = false;
            }

            @Override
            public String presentationString()
            {
                return cronExpression().get();
            }

            @Override
            public boolean isTaskRunning()
            {
                // See SchedulerMixin.ScheduleRunner::run
                return false;
            }

            @Override
            public long nextRun( long from )
            {
                long actualFrom = from;
                long firstRun = start().get().getMillis();
                if( firstRun > from )
                {
                    actualFrom = firstRun;
                }
                Long nextRun = new org.codeartisans.sked.cron.CronSchedule( cronExpression().get() )
                    .firstRunAfter( actualFrom );
                LOGGER.info( "CronSchedule::nextRun({}) is {}", from, firstRun );
                return nextRun;
            }
        }

    }