package cn.hutool.core.thread;

import cn.hutool.core.builder.Builder;
import cn.hutool.core.util.StrUtil;

import java.lang.Thread.UncaughtExceptionHandler;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicLong;

/**
 * ThreadFactory创建器<br>
 * 参考：Guava的ThreadFactoryBuilder
 *
 * @author looly
 * @since 4.1.9
 */
public class ThreadFactoryBuilder implements Builder<ThreadFactory>{
	private static final long serialVersionUID = 1L;

	/** 用于线程创建的线程工厂类 */
	private ThreadFactory backingThreadFactory;
	/** 线程名的前缀 */
	private String namePrefix;
	/** 是否守护线程，默认false */
	private Boolean daemon;
	/** 线程优先级 */
	private Integer priority;
	/** 未捕获异常处理器 */
	private UncaughtExceptionHandler uncaughtExceptionHandler;

	/**
	 * 创建{@link ThreadFactoryBuilder}
	 *
	 * @return {@link ThreadFactoryBuilder}
	 */
	public static ThreadFactoryBuilder create() {
		return new ThreadFactoryBuilder();
	}

	/**
	 * 设置用于创建基础线程的线程工厂
	 *
	 * @param backingThreadFactory 用于创建基础线程的线程工厂
	 * @return this
	 */
	public ThreadFactoryBuilder setThreadFactory(ThreadFactory backingThreadFactory) {
		this.backingThreadFactory = backingThreadFactory;
		return this;
	}

	/**
	 * 设置线程名前缀，例如设置前缀为hutool-thread-，则线程名为hutool-thread-1之类。
	 *
	 * @param namePrefix 线程名前缀
	 * @return this
	 */
	public ThreadFactoryBuilder setNamePrefix(String namePrefix) {
		this.namePrefix = namePrefix;
		return this;
	}

	/**
	 * 设置是否守护线程
	 *
	 * @param daemon 是否守护线程
	 * @return this
	 */
	public ThreadFactoryBuilder setDaemon(boolean daemon) {
		this.daemon = daemon;
		return this;
	}

	/**
	 * 设置线程优先级
	 *
	 * @param priority 优先级
	 * @return this
	 * @see Thread#MIN_PRIORITY
	 * @see Thread#NORM_PRIORITY
	 * @see Thread#MAX_PRIORITY
	 */
	public ThreadFactoryBuilder setPriority(int priority) {
		if (priority < Thread.MIN_PRIORITY) {
			throw new IllegalArgumentException(StrUtil.format("Thread priority ({}) must be >= {}", priority, Thread.MIN_PRIORITY));
		}
		if (priority > Thread.MAX_PRIORITY) {
			throw new IllegalArgumentException(StrUtil.format("Thread priority ({}) must be <= {}", priority, Thread.MAX_PRIORITY));
		}
		this.priority = priority;
		return this;
	}

	/**
	 * 设置未捕获异常的处理方式
	 *
	 * @param uncaughtExceptionHandler {@link UncaughtExceptionHandler}
	 * @return this
	 */
	public ThreadFactoryBuilder setUncaughtExceptionHandler(UncaughtExceptionHandler uncaughtExceptionHandler) {
		this.uncaughtExceptionHandler = uncaughtExceptionHandler;
		return this;
	}

	/**
	 * 构建{@link ThreadFactory}
	 *
	 * @return {@link ThreadFactory}
	 */
	@Override
	public ThreadFactory build() {
		return build(this);
	}

	/**
	 * 构建
	 *
	 * @param builder {@link ThreadFactoryBuilder}
	 * @return {@link ThreadFactory}
	 */
	private static ThreadFactory build(ThreadFactoryBuilder builder) {
		final ThreadFactory backingThreadFactory = (null != builder.backingThreadFactory)//
				? builder.backingThreadFactory //
				: Executors.defaultThreadFactory();
		final String namePrefix = builder.namePrefix;
		final Boolean daemon = builder.daemon;
		final Integer priority = builder.priority;
		final UncaughtExceptionHandler handler = builder.uncaughtExceptionHandler;
		final AtomicLong count = (null == namePrefix) ? null : new AtomicLong();
		return r -> {
			final Thread thread = backingThreadFactory.newThread(r);
			if (null != namePrefix) {
				thread.setName(namePrefix + count.getAndIncrement());
			}
			if (null != daemon) {
				thread.setDaemon(daemon);
			}
			if (null != priority) {
				thread.setPriority(priority);
			}
			if (null != handler) {
				thread.setUncaughtExceptionHandler(handler);
			}
			return thread;
		};
	}
}
