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/*
 * Copyright 2011 Jin Kwon.
 *
 * 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 com.googlecode.jinahya.fsm;


/**
 * Task for switching conditions.
 *
 * @author Jin Kwon
 */
public abstract class SwitchTask extends AbstractTask {


    /**
     * Creates a new instance.
     *
     * @param onMatchers matchers for switching on; none null; none empty
     * @param offMatchers matchers for switching off; none null; none empty
     */
    public SwitchTask(final TransitionMatcher[] onMatchers,
                      final TransitionMatcher... offMatchers) {

        super(onMatchers);

        if (offMatchers == null) {
            throw new NullPointerException("null offMatchers");
        }

        if (offMatchers.length == 0) {
            throw new NullPointerException("empty offMatchers");
        }

        this.offMatchers = offMatchers;
    }


    @Override
    public boolean matches(final Transition transition) {
        if (on) {
            return transition.matchesAny(offMatchers);
        } else { // off
            return super.matches(transition);
        }
    }


    @Override
    public void perform(final Transition transition) {
        if (on) {
            try {
                performOff(transition);
            } finally {
                on = false;
            }
        } else { // off;
            try {
                performOn(transition);
            } finally {
                on = true;
            }
        }
    }


    /**
     * Performs for switched on.
     *
     * @param transition transition
     */
    protected abstract void performOn(final Transition transition);


    /**
     * Performs for switched off.
     *
     * @param trasition transition
     */
    protected abstract void performOff(final Transition trasition);


    /** matchers for switching off. */
    private final TransitionMatcher[] offMatchers;


    /** on flag. */
    private volatile boolean on = false;


}