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/**
 * Copyright (C) 2011 Ovea 
 *
 * 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.ovea.system.pipe;

import com.ovea.system.util.IoUtils;

import java.io.Closeable;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.UUID;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicReference;

/**
 * @author Mathieu Carbou ([email protected])
 */
abstract class PipeSkeleton implements Pipe {

    private static enum State {READY, OPENED, CLOSED, INTERRUPTED, BROKEN}

    private static final PipeListener EMPTY = new PipeListenerAdapter();

    private final AtomicReference state = new AtomicReference(State.READY);
    private final String name;

    private PipeConnection connection;
    private PipeListener listener;
    private IN from;
    private OUT to;

    protected PipeSkeleton(String name, IN from, OUT to) {
        if (from == null) throw new IllegalArgumentException("Missing origin endpoint");
        if (to == null) throw new IllegalArgumentException("Missing destination endpoint");
        if (name == null) throw new IllegalArgumentException("Missing pipe name");
        this.from = from;
        this.to = to;
        this.name = name;
    }

    protected PipeSkeleton(IN from, OUT to) {
        this("pipe-" + UUID.randomUUID().toString(), from, to);
    }

    @Override
    public final String name() {
        return name;
    }

    @Override
    public final String toString() {
        return name;
    }

    @Override
    public final Pipe listenedBy(PipeListener listener) {
        if (listener == null) throw new IllegalArgumentException("Listener cannot be null");
        this.listener = new OncePipeListener(listener);
        return this;
    }

    @Override
    public final PipeConnection connect() {
        if (state.compareAndSet(State.READY, State.OPENED)) {
            connection = new Connection(this);
        }
        return connection;
    }

    @Override
    public final boolean isReady() {
        return state.get() == State.READY;
    }

    @Override
    public final boolean isOpened() {
        return state.get() == State.OPENED;
    }

    @Override
    public final boolean isClosed() {
        return state.get() == State.CLOSED;
    }

    @Override
    public final boolean isBroken() {
        return state.get() == State.BROKEN;
    }

    @Override
    public final boolean isInterrupted() {
        return state.get() == State.INTERRUPTED;
    }

    protected final boolean canCopy() {
        return !Thread.interrupted() && isOpened();
    }

    protected abstract void copy(IN from, OUT to) throws IOException, BrokenPipeException;

    private PipeListener listener() {
        PipeListener l = listener;
        return l == null ? EMPTY : l;
    }

    private static final class Connection implements PipeConnection {

        private final PipeSkeleton pipe;
        private final FutureTask