/*
 * Copyright (C) 2015 Laurent CLOUET
 * Author Laurent CLOUET <laurent.clouet@nopnop.net>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package com.sheepit.client;

import com.sheepit.client.os.OS;
import lombok.Data;

import java.util.Date;
import java.util.concurrent.atomic.AtomicLong;

import lombok.Setter;
import oshi.software.os.OSProcess;

/**
 * Provides facilities to track how long a render process takes,
 * how long different phases lasted
 * how many resources it uses and has used
 * and to end the process if necessary
 */
@Data public class RenderProcess {
	private long startTime;
	private long endTime;
	
	@Setter
	private int scenePrepDuration;
	@Setter
	private int renderDuration;
	@Setter
	private int postProcessingDuration;
	private int remainingDuration; // in seconds
	private AtomicLong memoryUsed; // in kB
	private long peakMemoryUsed; // in kB
	private int coresUsed;
	private Process process;
	private OSProcess osProcess;
	private Log log;
	
	public RenderProcess(Log _log) {
		process = null;
		osProcess = null;
		startTime = -1;
		endTime = -1;
		scenePrepDuration = -1;
		renderDuration = -1;
		postProcessingDuration = -1;
		memoryUsed = new AtomicLong(0);
		peakMemoryUsed = 0;
		coresUsed = 0;
		remainingDuration = 0;
		log = _log;
	}
	
	/**
	 * Update the Process object with the current memory usage
	 */
	public void update() {
		OSProcess osp = osProcess; // Shallow copy to try to not run into a race condition via being nulled
		try {
			if (osp != null && osp.updateAttributes()){ // We enter if updateAttributes() was successful
				long mem = osp.getResidentSetSize() / 1024; // Avoid multiple ram usage calls, because again, they might differ
				if (mem != 0){
					memoryUsed.set(mem);
					if (peakMemoryUsed < mem) {
						peakMemoryUsed = mem;
					}
				}
			}
		} catch (NullPointerException ex) { // We are racing the system itself, we can't avoid catching NPE's
			log.debug("RenderProcess::Handled process becoming unavailable mid-update");
			osProcess = null;
			memoryUsed.set(0);
		}
	}
	
	/**
	 * Get how long the render process has been running for
	 * @return duration in seconds
	 */
	public int getDuration() {
		if (startTime != -1 && endTime != -1) {
			return (int) ((endTime - startTime) / 1000);
		}
		else if (startTime != -1) {
			return (int) ((new Date().getTime() - startTime) / 1000);
		}
		return 0;
	}
	
	/**
	 * Kills the render process
	 */
	public void kill() {
		if (process != null){
			try {
				OS.getOS().kill(process);
				log.debug("RenderProcess::Process killed");
			} catch (NullPointerException ex) { // We are racing the system itself, we can't avoid catching NPE's
				log.debug("RenderProcess::Handled process becoming unavailable before getting killed");
			}
		}
	}
	
	/**
	 * Ends the render process by killing it and recording the time it ended
	 */
	public void finish() {
		kill();
		endTime = new Date().getTime();
		osProcess = null;
		process = null;
	}
	
	/**
	 * Records when the render process started
	 */
	public void start() {
		startTime = new Date().getTime();
	}
	
	/**
	 * Returns the exit value for the render process.
	 * @return the exit value of the process represented
	 *         by this Process object. By convention,
	 *         the value 0 indicates normal termination.
	 *         For this method it might also mean that the
	 *         process is still running.
	 *         Returns -1 if process is null.
	 * @see Process#exitValue()
	 */
	public int exitValue() {
		int value = 0;
		if (process == null) {
			return -1;
		}
		try {
			value = process.exitValue();
		}
		catch (IllegalThreadStateException e) {
			// the process is not finished yet
		}
		catch (Exception e) {
			// actually is for java.io.IOException: GetExitCodeProcess error=6, The handle is invalid
			// it was not declared throwable
			
			// the process is not finished yet
		}
		return value;
	}
}