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/**
 * Copyright (C) 2015 The Gravitee team (http://gravitee.io)
 *
 * 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 io.gravitee.common.component;

/**
 * @author David BRASSELY (brasseld at gmail.com)
 */
public class Lifecycle {

    public static enum State {
        INITIALIZED,
        STOPPED,
        STOPPING,
        STARTED,
        CLOSED,
    }

    private volatile State state = State.INITIALIZED;

    public State state() {
        return this.state;
    }

    /**
     * Returns true if the state is initialized.
     */
    public boolean initialized() {
        return state == State.INITIALIZED;
    }

    /**
     * Returns true if the state is started.
     */
    public boolean started() {
        return state == State.STARTED;
    }

    /**
     * Returns true if the state is stopped.
     */
    public boolean stopped() {
        return state == State.STOPPED;
    }

    /**
     * Returns true if the state is closed.
     */
    public boolean closed() {
        return state == State.CLOSED;
    }

    public boolean moveToStarted() {
        State localState = this.state;
        if (localState == State.INITIALIZED || localState == State.STOPPED) {
            state = State.STARTED;
            return true;
        }
        if (localState == State.STARTED) {
            return false;
        }
        if (localState == State.CLOSED) {
            throw new IllegalStateException("Can't move to started state when closed");
        }
        throw new IllegalStateException("Can't move to started with unknown state");
    }

    public boolean moveToStopping() {
        state = State.STOPPING;
        return true;
    }

    public boolean moveToStopped() {
        State localState = state;
        if (localState == State.STARTED || localState == State.STOPPING) {
            state = State.STOPPED;
            return true;
        }
        if (localState == State.INITIALIZED || localState == State.STOPPED) {
            return false;
        }
        if (localState == State.CLOSED) {
            throw new IllegalStateException("Can't move to stopped state when closed");
        }
        throw new IllegalStateException("Can't move to stopped with unknown state");
    }

    @Override
    public String toString() {
        return state.toString();
    }
}