/**
 *  Copyright (C) 2010 Cloud.com, Inc.  All rights reserved.
 * 
 * This software is licensed under the GNU General Public License v3 or later.
 * 
 * It is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 */

package com.cloud.vm;

import java.util.List;
import java.util.Set;

import com.cloud.utils.fsm.FiniteState;
import com.cloud.utils.fsm.StateMachine;
import com.cloud.vm.VirtualMachine.Event;

public enum State implements FiniteState<State, Event> {
    Creating(true, "VM is being created"),
    Starting(true, "VM is being started.  At this state, you should find host id filled which means it's being started on that host."),
    Running(false, "VM is running.  host id has the host that it is running on."),
    Stopping(true, "VM is being stopped.  host id has the host that it is being stopped on."),
    Stopped(false, "VM is stopped.  host id should be null."),
    Destroyed(false, "VM is marked for destroy."),
    Expunging(true, "VM is being   expunged."),
    Migrating(true, "VM is being migrated.  host id holds to from host"),
    Error(false, "VM is in error"),
    Unknown(false, "VM state is unknown.");
    
    private final boolean _transitional;
    String _description;
    
    private State(boolean transitional, String description) {
    	_transitional = transitional;
    	_description = description;
    }
    
    @Override
    public String getDescription() {
        return _description;
    }
    
    public boolean isTransitional() {
    	return _transitional;
    }
    
    @Override
    public State getNextState(VirtualMachine.Event e) {
        return s_fsm.getNextState(this, e);
    }

    @Override
    public List<State> getFromStates(VirtualMachine.Event e) {
        return s_fsm.getFromStates(this, e);
    }
    
    @Override
    public Set<Event> getPossibleEvents() {
        return s_fsm.getPossibleEvents(this);
    }
    
    @Override
    public StateMachine<State, Event> getStateMachine() {
        return s_fsm;
    }
    
    
    protected static final StateMachine<State, VirtualMachine.Event> s_fsm = new StateMachine<State, VirtualMachine.Event>();
    static {
    	s_fsm.addTransition(null, VirtualMachine.Event.CreateRequested, State.Creating);
    	s_fsm.addTransition(State.Creating, VirtualMachine.Event.OperationSucceeded, State.Stopped);
    	s_fsm.addTransition(State.Creating, VirtualMachine.Event.OperationFailed, State.Error);
    	s_fsm.addTransition(State.Stopped, VirtualMachine.Event.StartRequested, State.Starting);
    	s_fsm.addTransition(State.Stopped, VirtualMachine.Event.DestroyRequested, State.Destroyed);
    	s_fsm.addTransition(State.Error, VirtualMachine.Event.DestroyRequested, State.Destroyed);
    	s_fsm.addTransition(State.Stopped, VirtualMachine.Event.StopRequested, State.Stopped);
    	s_fsm.addTransition(State.Stopped, VirtualMachine.Event.AgentReportStopped, State.Stopped);
    	s_fsm.addTransition(State.Starting, VirtualMachine.Event.OperationRetry, State.Starting);
    	s_fsm.addTransition(State.Starting, VirtualMachine.Event.OperationSucceeded, State.Running);
    	s_fsm.addTransition(State.Starting, VirtualMachine.Event.OperationFailed, State.Stopped);
    	s_fsm.addTransition(State.Starting, VirtualMachine.Event.AgentReportRunning, State.Running);
    	s_fsm.addTransition(State.Starting, VirtualMachine.Event.AgentReportStopped, State.Stopped);
    	s_fsm.addTransition(State.Destroyed, VirtualMachine.Event.RecoveryRequested, State.Stopped);
    	s_fsm.addTransition(State.Destroyed, VirtualMachine.Event.ExpungeOperation, State.Expunging);
    	s_fsm.addTransition(State.Creating, VirtualMachine.Event.MigrationRequested, State.Destroyed);
    	s_fsm.addTransition(State.Running, VirtualMachine.Event.MigrationRequested, State.Migrating);
    	s_fsm.addTransition(State.Running, VirtualMachine.Event.AgentReportRunning, State.Running);
    	s_fsm.addTransition(State.Running, VirtualMachine.Event.AgentReportStopped, State.Stopped);
    	s_fsm.addTransition(State.Running, VirtualMachine.Event.StopRequested, State.Stopping);
    	s_fsm.addTransition(State.Migrating, VirtualMachine.Event.MigrationRequested, State.Migrating);
    	s_fsm.addTransition(State.Migrating, VirtualMachine.Event.OperationSucceeded, State.Running);
    	s_fsm.addTransition(State.Migrating, VirtualMachine.Event.OperationFailed, State.Running);
    	s_fsm.addTransition(State.Migrating, VirtualMachine.Event.MigrationFailedOnSource, State.Running);
    	s_fsm.addTransition(State.Migrating, VirtualMachine.Event.MigrationFailedOnDest, State.Running);
    	s_fsm.addTransition(State.Migrating, VirtualMachine.Event.AgentReportRunning, State.Running);
    	s_fsm.addTransition(State.Migrating, VirtualMachine.Event.AgentReportStopped, State.Stopped);
    	s_fsm.addTransition(State.Stopping, VirtualMachine.Event.OperationSucceeded, State.Stopped);
    	s_fsm.addTransition(State.Stopping, VirtualMachine.Event.OperationFailed, State.Running);
    	s_fsm.addTransition(State.Stopping, VirtualMachine.Event.AgentReportRunning, State.Running);
    	s_fsm.addTransition(State.Stopping, VirtualMachine.Event.AgentReportStopped, State.Stopped);
    	s_fsm.addTransition(State.Stopping, VirtualMachine.Event.StopRequested, State.Stopping);
    	s_fsm.addTransition(State.Expunging, VirtualMachine.Event.OperationFailed, State.Expunging);
    	s_fsm.addTransition(State.Expunging, VirtualMachine.Event.ExpungeOperation, State.Expunging);
    }
}