/**
 * Copyright (C) 2016 Marc Gonzalez Diez Open Source Project
 * <p>
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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 executor;

import com.mgdiez.domain.executor.ThreadExecutor;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import javax.inject.Inject;
import javax.inject.Singleton;

/**
 * Decorated {@link ThreadPoolExecutor}
 */
@Singleton
public class JobExecutor implements ThreadExecutor {

    private static final int INITIAL_POOL_SIZE = 3;

    private static final int MAX_POOL_SIZE = 5;

    // Sets the amount of time an idle thread waits before terminating
    private static final int KEEP_ALIVE_TIME = 10;

    // Sets the Time Unit to seconds
    private static final TimeUnit KEEP_ALIVE_TIME_UNIT = TimeUnit.SECONDS;

    private final BlockingQueue<Runnable> workQueue;

    private final ThreadPoolExecutor threadPoolExecutor;

    private final ThreadFactory threadFactory;

    private static class LazyHolder {
        private static final JobExecutor INSTANCE = new JobExecutor();
    }

    public static JobExecutor getInstance() {
        return LazyHolder.INSTANCE;
    }

    @Inject
    public JobExecutor() {
        this.workQueue = new LinkedBlockingQueue<>();
        this.threadFactory = new JobThreadFactory();
        this.threadPoolExecutor = new ThreadPoolExecutor(INITIAL_POOL_SIZE, MAX_POOL_SIZE, KEEP_ALIVE_TIME, KEEP_ALIVE_TIME_UNIT,
                this.workQueue, this.threadFactory);
    }

    @Override
    public void execute(Runnable runnable) {
        if (runnable == null) {
            throw new IllegalArgumentException("Runnable to execute cannot be null");
        }
        this.threadPoolExecutor.execute(runnable);
    }

    private static class JobThreadFactory implements ThreadFactory {
        private static final String THREAD_NAME = "android_";

        private int counter = 0;

        @Override
        public Thread newThread(Runnable runnable) {
            return new Thread(runnable, THREAD_NAME + counter);
        }
    }
}