/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.maven.plugin.surefire.booterclient.lazytestprovider;

import java.io.IOException;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Semaphore;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.maven.surefire.api.booter.Command;
import org.apache.maven.surefire.api.booter.Shutdown;

import static org.apache.maven.surefire.api.booter.Command.BYE_ACK;
import static org.apache.maven.surefire.api.booter.Command.NOOP;
import static org.apache.maven.surefire.api.booter.Command.SKIP_SINCE_NEXT_TEST;
import static org.apache.maven.surefire.api.booter.Command.TEST_SET_FINISHED;
import static org.apache.maven.surefire.api.booter.Command.toRunClass;
import static org.apache.maven.surefire.api.booter.Command.toShutdown;

/**
 * An {@link java.io.InputStream} that, when read, provides test class names out of a queue.
 * <br>
 * The Stream provides only one test at a time, but only after {@link #provideNewTest()} has been invoked.
 * <br>
 * The instance is used only in reusable forks in {@link org.apache.maven.plugin.surefire.booterclient.ForkStarter}
 * by one Thread.
 *
 * @author Andreas Gudian
 * @author Tibor Digana (tibor17)
 */
public final class TestProvidingInputStream extends DefaultCommandReader {
    private final Semaphore barrier = new Semaphore(0);

    private final Queue<Command> commands = new ConcurrentLinkedQueue<>();

    private final AtomicBoolean closed = new AtomicBoolean();

    private final Queue<String> testClassNames;

    /**
     * C'tor
     *
     * @param testClassNames source of the tests to be read from this stream
     */
    public TestProvidingInputStream(Queue<String> testClassNames) {
        this.testClassNames = testClassNames;
    }

    /**
     * For testing purposes.
     */
    void testSetFinished() {
        if (canContinue()) {
            commands.add(TEST_SET_FINISHED);
            barrier.release();
        }
    }

    @Override
    public void skipSinceNextTest() {
        if (canContinue()) {
            commands.add(SKIP_SINCE_NEXT_TEST);
            barrier.release();
        }
    }

    @Override
    public void shutdown(Shutdown shutdownType) {
        if (canContinue()) {
            commands.add(toShutdown(shutdownType));
            barrier.release();
        }
    }

    @Override
    public void noop() {
        if (canContinue()) {
            commands.add(NOOP);
            barrier.release();
        }
    }

    @Override
    public void acknowledgeByeEventReceived() {
        if (canContinue()) {
            commands.add(BYE_ACK);
            barrier.release();
        }
    }

    @Override
    protected Command nextCommand() {
        Command cmd = commands.poll();
        if (cmd == null) {
            String cmdData = testClassNames.poll();
            return cmdData == null ? TEST_SET_FINISHED : toRunClass(cmdData);
        } else {
            return cmd;
        }
    }

    @Override
    protected void beforeNextCommand() throws IOException {
        awaitNextTest();
    }

    @Override
    public boolean isClosed() {
        return closed.get();
    }

    /**
     * Signal that a new test is to be provided.
     */
    @Override
    public void provideNewTest() {
        if (canContinue()) {
            barrier.release();
        }
    }

    @Override
    public void close() {
        if (closed.compareAndSet(false, true)) {
            barrier.drainPermits();
            barrier.release();
        }
    }

    private void awaitNextTest() throws IOException {
        try {
            barrier.acquire();
        } catch (InterruptedException e) {
            throw new IOException(e.getLocalizedMessage(), e);
        }
    }
}
