/*-
 * #%L
 * Common functionality widely used across SciJava modules.
 * %%
 * Copyright (C) 2021 - 2024 SciJava developers.
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * #L%
 */

package org.scijava.common3;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Map;

/**
 * Utility class for working with {@link Thread}s.
 *
 * @author Curtis Rueden
 * @author Gabriel Selzer
 */
public final class Threads {

	private static final String NL = System.getProperty("line.separator");

	private Threads() {
		// prevent instantiation of utility class
	}

	/** Extracts the given exception's corresponding stack trace to a string. */
	public static String stackTrace(final Throwable t) {
		try {
			final var out = new ByteArrayOutputStream();
			t.printStackTrace(new PrintStream(out, false, "UTF-8"));
			return new String(out.toByteArray(), "UTF-8");
		}
		catch (final IOException exc) {
			return null;
		}
	}

	/**
	 * Provides a stack dump of the given thread.
	 * <p>
	 * The output is similar to a subset of that given when Ctrl+\ (or Ctrl+Pause
	 * on Windows) is pressed from the console.
	 * </p>
	 */
	public static String stackTrace(final Thread thread) {
		final var sb = new StringBuilder();
		dumpThread(thread, thread.getStackTrace(), sb);
		return sb.toString();
	}

	/**
	 * Provides a complete dump of all threads.
	 * <p>
	 * The output is similar to a subset of that given when Ctrl+\ (or Ctrl+Pause
	 * on Windows) is pressed from the console.
	 */
	public static String dumpAll() {
		final var sb = new StringBuilder();

		final var stackTraces = Thread
			.getAllStackTraces();

		// sort list of threads by name
		final var threads = new ArrayList<Thread>(stackTraces.keySet());
		Collections.sort(threads, (t1, t2) -> t1.getName().compareTo(t2.getName()));

		for (final var t : threads) {
			dumpThread(t, stackTraces.get(t), sb);
		}

		return sb.toString();
	}

	// -- Helper methods --

	private static void dumpThread(final Thread t,
		final StackTraceElement[] trace, final StringBuilder sb)
	{
		threadInfo(t, sb);
		for (final var element : trace) {
			sb.append("\tat ");
			sb.append(element);
			sb.append(NL);
		}
		sb.append(NL);
	}

	private static void threadInfo(final Thread t, final StringBuilder sb) {
		sb.append("\"");
		sb.append(t.getName());
		sb.append("\"");
		if (!t.isAlive()) sb.append(" DEAD");
		if (t.isInterrupted()) sb.append(" INTERRUPTED");
		if (t.isDaemon()) sb.append(" daemon");
		sb.append(" prio=");
		sb.append(t.getPriority());
		sb.append(" id=");
		sb.append(t.getId());
		sb.append(" group=");
		sb.append(t.getThreadGroup().getName());
		sb.append(NL);
		sb.append("   java.lang.Thread.State: ");
		sb.append(t.getState());
		sb.append(NL);
	}
}
