/**
 * Copyright 2005 JBoss Inc
 *
 * 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.drools.common;

import org.drools.Agenda;
import org.drools.runtime.Calendars;
import org.drools.time.Job;
import org.drools.time.JobContext;
import org.drools.time.JobHandle;
import org.drools.time.Trigger;
import org.drools.time.impl.PointInTimeTrigger;

/**
 * Scheduler for rules requiring truth duration.
 * 
 * @author <a href="mailto:bob@werken.com">bob mcwhirter </a>
 */
final class Scheduler {
    // ------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------
    /**
     * Construct.
     */
    private Scheduler() {
    }

    /**
     * Schedule an agenda item.
     * 
     * @param item
     *            The item to schedule.
     * @param wm 
     * @param workingMemory
     *            The working memory session.
     */
    public static void scheduleAgendaItem(final ScheduledAgendaItem item, InternalAgenda agenda, InternalWorkingMemory wm) {
        String[] calendarNames = item.getRule().getCalendars();
        Calendars calendars = wm.getCalendars();
        
        Trigger trigger = item.getRule().getTimer().createTrigger( ((InternalWorkingMemory)agenda.getWorkingMemory()).getTimerService().getCurrentTime(), calendarNames, calendars);
        
        ActivationTimerJob job = new ActivationTimerJob();        
        ActivationTimerJobContext ctx = new ActivationTimerJobContext( trigger, item, agenda );        
                
        JobHandle jobHandle = ((InternalWorkingMemory)agenda.getWorkingMemory()).getTimerService().scheduleJob( job, ctx, trigger );
        item.setJobHandle( jobHandle );
    }
    
    public static void removeAgendaItem(final ScheduledAgendaItem item, final InternalAgenda agenda) {
        ((InternalWorkingMemory)agenda.getWorkingMemory()).getTimerService().removeJob( item.getJobHandle() );
    }    
    
    public static class ActivationTimerJob implements Job {
        public void execute(JobContext ctx) {
            InternalAgenda agenda = ( InternalAgenda ) ((ActivationTimerJobContext)ctx).getAgenda();
            ScheduledAgendaItem item  = ((ActivationTimerJobContext)ctx).getScheduledAgendaItem();
            
            agenda.fireActivation( item );
            if ( ((ActivationTimerJobContext)ctx).getTrigger().hasNextFireTime() == null ) {
                agenda.getScheduledActivationsLinkedList().remove( item );
            } else {
                // the activation has been rescheduled, the Agenda would have set it's activated to false
                // so reset the activated to true here
                item.setActivated( true );
            }
            agenda.getWorkingMemory().fireAllRules();            
        }        
    }
    
    public static class ActivationTimerJobContext implements JobContext {
        private JobHandle jobHandle;
        private ScheduledAgendaItem scheduledAgendaItem;
        private Agenda agenda;          
        private Trigger trigger;
        
        public ActivationTimerJobContext(Trigger trigger,
                                         ScheduledAgendaItem scheduledAgendaItem,
                                   Agenda agenda) {
            this.trigger = trigger;
            this.scheduledAgendaItem = scheduledAgendaItem;
            this.agenda = agenda;
        }
        
        public Agenda getAgenda() {
            return this.agenda;
        }
        
        public ScheduledAgendaItem getScheduledAgendaItem() {
            return this.scheduledAgendaItem;
        }

        public JobHandle getJobHandle() {
            return this.jobHandle;
        }

        public void setJobHandle(JobHandle jobHandle) {
            this.jobHandle = jobHandle;
        } 
        
        public Trigger getTrigger() {
            return trigger;
        }        
    }    
}