/* -*- mode: java; c-basic-offset: 2; indent-tabs-mode: nil -*- */

/*
	Copyright (c) The Processing Foundation 2015
	Hardware I/O library developed by Gottfried Haider as part of GSoC 2015

	This library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Lesser General Public
	License as published by the Free Software Foundation; either
	version 2.1 of the License, or (at your option) any later version.

	This library 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
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General
	Public License along with this library; if not, write to the
	Free Software Foundation, Inc., 59 Temple Place, Suite 330,
	Boston, MA	02111-1307	USA
*/

package processing.io;

import processing.io.NativeInterface;

import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;


/**
 *	@webref
 */
public class LED {

	protected String dev;
	protected int maxBrightness;
	protected int prevBrightness;
	protected String prevTrigger;


	/**
	 *	Opens a LED device
	 *	@param dev device name
	 *	@see list
	 *	@webref
	 */
	public LED(String dev) {
		NativeInterface.loadLibrary();
		this.dev = dev;

		if (NativeInterface.isSimulated()) {
			return;
		}

		// read maximum brightness
		try {
			Path path = Paths.get("/sys/class/leds/" + dev + "/max_brightness");
			String tmp = new String(Files.readAllBytes(path));
			maxBrightness = Integer.parseInt(tmp.trim());
		} catch (Exception e) {
			System.err.println(e.getMessage());
			throw new RuntimeException("Unable to read maximum brightness");
		}

		// read current trigger setting to be able to restore it later
		try {
			Path path = Paths.get("/sys/class/leds/" + dev + "/trigger");
			String tmp = new String(Files.readAllBytes(path));
			int start = tmp.indexOf('[');
			int end = tmp.indexOf(']', start);
			if (start != -1 && end != -1) {
				prevTrigger = tmp.substring(start+1, end);
			}
		} catch (Exception e) {
			System.err.println(e.getMessage());
			throw new RuntimeException("Unable to read trigger setting");
		}

		// read current brightness to be able to restore it later
		try {
			Path path = Paths.get("/sys/class/leds/" + dev + "/brightness");
			String tmp = new String(Files.readAllBytes(path));
			prevBrightness = Integer.parseInt(tmp.trim());
		} catch (Exception e) {
			System.err.println(e.getMessage());
			throw new RuntimeException("Unable to read current brightness");
		}

		// disable trigger
		String fn = "/sys/class/leds/" + dev + "/trigger";
		int ret = NativeInterface.writeFile(fn, "none");
		if (ret < 0) {
			if (ret == -13) {		 // EACCES
				System.err.println("You might need to install a custom udev rule to allow regular users to modify /sys/class/leds/*.");
			}
			throw new RuntimeException(NativeInterface.getError(ret));
		}
	}


	/**
	 *	Sets the brightness
	 *	@param bright 0.0 (off) to 1.0 (maximum)
	 *	@webref
	 */
	public void brightness(float bright) {
		if (bright < 0.0 || 1.0 < bright) {
			System.err.println("Brightness must be between 0.0 and 1.0.");
			throw new IllegalArgumentException("Illegal argument");
		}

		if (NativeInterface.isSimulated()) {
			return;
		}

		String fn = "/sys/class/leds/" + dev + "/brightness";
		int ret = NativeInterface.writeFile(fn, Integer.toString((int)(bright * maxBrightness)));
		if (ret < 0) {
			throw new RuntimeException(fn + ": " + NativeInterface.getError(ret));
		}
	}


	/**
	 *	Restores the previous state
	 *	@webref
	 */
	public void close() {
		if (NativeInterface.isSimulated()) {
			return;
		}

		// restore previous settings
		String fn = "/sys/class/leds/" + dev + "/brightness";
		int ret = NativeInterface.writeFile(fn, Integer.toString(prevBrightness));
		if (ret < 0) {
			throw new RuntimeException(fn + ": " + NativeInterface.getError(ret));
		}

		fn = "/sys/class/leds/" + dev + "/trigger";
		ret = NativeInterface.writeFile(fn, prevTrigger);
		if (ret < 0) {
			throw new RuntimeException(fn + ": " + NativeInterface.getError(ret));
		}
	}


	/**
	 *	Lists all available LED devices
	 *	@return String array
	 *	@webref
	 */
	public static String[] list() {
		if (NativeInterface.isSimulated()) {
			// as on the Raspberry Pi
			return new String[]{ "led0", "led1" };
		}

		ArrayList<String> devs = new ArrayList<>();
		File dir = new File("/sys/class/leds");
		File[] files = dir.listFiles();
		if (files != null) {
			for (File file : files) {
				devs.add(file.getName());
			}
		}
		// listFiles() does not guarantee ordering
		String[] tmp = devs.toArray(new String[devs.size()]);
		Arrays.sort(tmp);
		return tmp;
	}
}
