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The Amazon Web Services SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2012-2014 Amazon.com, Inc. or its affiliates. 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. A copy of the License is
 * located at
 * 
 * http://aws.amazon.com/apache2.0
 * 
 * or in the "license" file accompanying this file. This file 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 com.amazonaws.services.simpleworkflow.flow.worker;

import com.amazonaws.services.simpleworkflow.model.CancelTimerDecisionAttributes;
import com.amazonaws.services.simpleworkflow.model.Decision;
import com.amazonaws.services.simpleworkflow.model.DecisionType;
import com.amazonaws.services.simpleworkflow.model.HistoryEvent;
import com.amazonaws.services.simpleworkflow.model.StartTimerDecisionAttributes;

/**
 * Timer doesn't have separate initiation decision as it is started immediately.
 * But from the state machine point of view it is modeled the same as activity
 * with no TimerStarted event used as initiation event.
 * 
 * @author fateev
 */
class TimerDecisionStateMachine extends DecisionStateMachineBase {

    private StartTimerDecisionAttributes attributes;
    
    private boolean canceled;

    public TimerDecisionStateMachine(DecisionId id, StartTimerDecisionAttributes attributes) {
        super(id);
        this.attributes = attributes;
    }

    /**
     * Used for unit testing
     */
    TimerDecisionStateMachine(DecisionId id, StartTimerDecisionAttributes attributes, DecisionState state) {
        super(id, state);
        this.attributes = attributes;
    }
    
    @Override
    public Decision getDecision() {
        switch (state) {
        case CREATED:
            return createStartTimerDecision();
        case CANCELED_AFTER_INITIATED:
            return createCancelTimerDecision();
        default:
            return null;
        }
    }

    @Override
    public void handleDecisionTaskStartedEvent() {
        switch (state) {
        case CANCELED_AFTER_INITIATED:
            stateHistory.add("handleDecisionTaskStartedEvent");
            state = DecisionState.CANCELLATION_DECISION_SENT;
            stateHistory.add(state.toString());
            break;
        default:
            super.handleDecisionTaskStartedEvent();
        }
    }

    @Override
    public void handleCancellationFailureEvent(HistoryEvent event) {
        switch (state) {
        case CANCELLATION_DECISION_SENT:
            stateHistory.add("handleCancellationFailureEvent");
            state = DecisionState.INITIATED;
            stateHistory.add(state.toString());
            break;
        default:
            super.handleCancellationFailureEvent(event);
        }
    }
    
    @Override
    public void cancel(Runnable immediateCancellationCallback) {
        canceled = true;
        immediateCancellationCallback.run();
        super.cancel(null);
    }

    /**
     * As timer is canceled immediately there is no need for waiting after
     * cancellation decision was sent.
     */
    @Override
    public boolean isDone() {
        return state == DecisionState.COMPLETED || canceled;
    }

    private Decision createCancelTimerDecision() {
        CancelTimerDecisionAttributes tryCancel = new CancelTimerDecisionAttributes();
        tryCancel.setTimerId(attributes.getTimerId());
        Decision decision = new Decision();
        decision.setCancelTimerDecisionAttributes(tryCancel);
        decision.setDecisionType(DecisionType.CancelTimer.toString());
        return decision;
    }

    private Decision createStartTimerDecision() {
        Decision decision = new Decision();
        decision.setStartTimerDecisionAttributes(attributes);
        decision.setDecisionType(DecisionType.StartTimer.toString());
        return decision;
    }

}