#!/usr/bin/env python

import getopt, sys, os, struct, time;

iBLmax = 255;
iBLmin = 12; # Below 12 it won't turn back on.

# Path to the PCI adapter.
sPCIBus = "/sys/bus/pci/devices/0000:00:02.0/config";

def setBL(param):
	fBacklight.seek(iBLO);
	fBacklight.write(struct.pack("B", param));
	fBacklight.flush();

def printUsage():
	print "Usage: %s [options]" % (sys.argv[0],)
	print """Where options are:
-h, --help		Display this usage message.
-s, --set		Set the backlight at a specific percentage.
-i, --inc		Increase backlight from current setting.
-d, --dec		Decrease backlight from current setting.
-g, --get		Get the current backlight in percent.
-t, --time		Specifies the time in millisecond for the fade in/out.

--gethex		Gets the backlight setting in hex.
--sethex		Sets the backlight setting in hex.

All percentage are float numbers and may contain decimals."""
	sys.exit(2);

if len(sys.argv) < 2:
	printUsage();

sLongOpts = [
	"help",
	"set=",
	"inc=",
	"dec=",
	"get",
	"time=",
	"gethex",
	"sethex=",
];

try:
	sArgs = getopt.getopt(sys.argv[1:], "hs:i:d:gt:", sLongOpts)[0];
except:
	printUsage();

if os.geteuid() != 0:
	args = [ "/usr/bin/sudo" ];
	args.extend(sys.argv);
	os.execv(args[0], args);

iBLO = 0xF4; # Backlight Offset
fBacklight = file(sPCIBus, 'r+');
fBacklight.seek(iBLO);
iCurBL = struct.unpack("B", fBacklight.read(1))[0];
iCurBLP = iCurBL * 100 / 255;
iSetting = 100;
iFade = 0;

for (arg, param) in sArgs:
	arg = arg.lower();
	if arg == "--help" or arg == "-h":
		printUsage();
	if arg == "--get" or arg == "-g":
		print "%d" % (iCurBLP,)
		sys.exit(0);
	if arg == "--set" or arg == "-s":
		iSetting = float(param);
	if arg == "--inc" or arg == "-i":
		iSetting = float(param) + iCurBLP
	if arg == "--dec" or arg == "-d":
		iSetting = -float(param) + iCurBLP
	if arg == "--time" or arg == "-t":
		iFade = float(param)/1000;
	if arg == "--sethex":
		setBL(int(param));
		sys.exit(0);
	if arg == "--gethex":
		print "%d" % (iCurBL,);
		sys.exit(0);

iBL = int(iSetting * 255 / 100);

if iBL > iBLmax: iBL = iBLmax;
if iBL < iBLmin: iBL = iBLmin;

iUD = 1;
if iCurBL > iBL: iUD = -1;

try:
	iTime = iFade / abs(iCurBL - iBL);
except ZeroDivisionError:
	iFade = 0;

try:
	if iFade > 0:
		for i in range(iCurBL, iBL, iUD):
			setBL(i);
			time.sleep(iTime);
except: pass;

setBL(iBL);
fBacklight.close();