#!/usr/bin/perl -w

# TODO: I reworked the argument parsing and broke the formatted output
# It was terrible in the first place, so rework that too.
#
# Work on a `date`-like format like:
#   "+%c/%m = %p\%"
# %c - Current absolute
# %m - Maximum absolute value
# %p - Current percent
#
# to output like:
#   1000/10000 = 10%
#   
# Create a new array of hashes to classify the ARGV elements, eg:
#   $0 + "+%c" -= 10 +=4 =1 =100 "+%p"
#   [
#       {
#           "action" => "increment",
#           "value"  => 1
#       },{
#           "action" => "print",
#           "value"  => "+%c"
#       },{
#           "action" => "decrement",
#           "value"  => 10
#       },{
#           "action" => "increment",
#           "value"  => 4
#       },{
#           "action" => "set",
#           "value"  => 1
#       },{
#           "action" => "set",
#           "value"  => 100
#       },{
#           "action" => "print",
#           "value"  => "+%p"
#       }
#   ]
#
# Process all of these in order. Add an option to show/hide action output
# so you can either get (shown):
#   100% 100000 90% 94% 1% 100% 100%
# or (hidden):
#   100000 100%
#
# All of the events would still occur between the output values.
#
# Add a delay option between increments and a delay between actions (does not
# apply to 'print'). This could be used to make a gradual sweep with:
#
# --delay-increment=100 --delay-action=0
#
# or to blink with:
#
# --delay-increment=0 --delay-action=1000
#
# With the latter, you could even have the backlight do morse code:
# clear |    S ( . . . )     |pause|            O ( _ _ _ )            |pause|
#     =0 =100 =0 =100 =0 =100 =0 =0 =100 =100 =0 =100 =100 =0 =100 =100 =0 =0 ...
#
# Perhaps add an argument to repeat indefinitely. This is all getting a bit
# silly, but kinda fun to think about.

# Files containing current and max brightness values
my $cur_file = "/sys/class/backlight/intel_backlight/brightness";
my $max_file = "/sys/class/backlight/intel_backlight/max_brightness";
my $last_file = "/home/jpm/.config/blc.last";

sub to_percent
{
        my $value = shift;
        $value = int($value/get_max()*100);
        return $value . '%';
}

sub get_offset
{
        return int(get_max()/100);
}

sub get_current
{
        open(my $c,'<',"$cur_file");
        my $current = <$c>;
        close $c;
        chomp $current;
        return $current;
}

sub get_max
{
        open(my $m,'<',"$max_file");
        my $max = <$m>;
        close $m;
        chomp $max;
        return $max;
}

sub get_min
{
        return int((get_max()/100)+2);
}

sub writable
{
        if (! -w $cur_file) {
		die "You don't have permission to write $cur_file\n";
        }
	return 1;
}

sub increment
{
        if (writable()) {
                my $current = get_current();
                my $max = get_max();
                my $target = $current+get_offset();
                if ($target > $max) {
                        $target = $max;
                }
                open(my $c,'>',"$cur_file");
                print $c $target;
                close $c;
                return $target;
        }
}

sub decrement
{
        if (writable()) {
                my $current = get_current();
                my $min = get_min();
                my $target = $current-get_offset();
                if ($target < $min) {
                        $target = $min;
                }
                open(my $c,'>',"$cur_file");
                print $c $target;
                close $c;
                return $target;
        }
}

sub set
{
        my $value = shift;
        if (writable()) {
                $current = get_current();
                if ($value > $current) {
                        for (my $i=$current;$i<=$value;$i++) {
                                open(my $c,'>',"$cur_file");
                                print $c $i;
                                close $c;
                        }
                } else {
                        for (my $i=$current;$i>=$value;$i--) {
                                open(my $c,'>',"$cur_file");
                                print $c $i;
                                close $c;
                        }
                }
                return $value;
        }
}

sub help
{
        print "
Backlight Control

Usage: blc.pl [--silent|--notify] [OPTION] [VALUE]

With no option the backlight information is printed as JSON.

Output printed to STDOUT unless:

--silent  Do not display output (overrides --notify)
--notify  Send output to notification daemon. --notify=N will
          change the display duration in ms. Default is 200ms

Output option must preceed the first Action option.

Actions:

= VALUE   Set backlight to specific value. VALUE greater than
          100 will be treated as absolute value. VALUE eqaul to
          or less than 100 will be treated as a percentage
+         Increment by 1%
+= VALUE  Increment by VALUE percent
-         Decrement by 1%
-= VALUE  Decrement by VALUE percent

Actions corrected to 1% or 100% if over or under. All actions
provide output as a percentage, with the % symbol.

Final percentage printed as below, skipping other options.

Print:

==        Print current absolute value
^         Print maximum absolute value
%         Print current percentage (does not include % symbol)
--help    Help (not impacted by --silent or --notify)
--HELP    Advanced help (same as above)

Any other option will be printed literally";
}

sub advanced
{
        $current = get_current();
        $max = get_max();
        print ".

Print functions can be strung together but command will exit
with the first non-print option. eg.

        \$ blc.pl == / ^
        21/100
        \$ blc.pl == ++
        ('==' ignored)
        (Backlight incremented)

Escape options with \\ in quotes to display them literally. eg.

        \$ blc.pl == / ^ '\\=' % \'\\%\'
        " . $current . "/" . $max . "=" . int($current/$max*100) . "%

Only one \'\\' is removed per block. eg.

        \$ blc.pl '\\% \\'
        % \\

";
}

my $current = get_current();
my (@output, $target, $silent, $notify);

my $operation_found = 0;
if (scalar @ARGV) {
	while ($arg = shift) {
                if ($arg eq '%') {
                        push @output,int(get_current()/get_max()*100);
                } elsif ($arg eq '^') {
                        push @output,get_max();
                } elsif ($arg eq '==') {
                        push @output,get_current();
                } elsif ($arg eq '--help') {
                        help();
                        print " (see --HELP).\n\n";
                        exit();
                } elsif ($arg eq '--HELP') {
                        help();
                        advanced();
                        exit();
                } elsif ($arg eq '--silent') {
                        $silent = 1;
                } elsif ($arg =~ /^--notify/) {
                        $notify = 1;
                        if ($arg =~ /=[0-9]+$/) {
                                $duration = $arg;
                                $duration =~ s/.*=([0-9]+)/$1/;
                        } else {
                                $duration = 1000;
                        }
		} elsif ($arg eq '+') {
			unshift(@ARGV,1);
			unshift(@ARGV,'+=');
                } elsif ($arg =~ /^\+=/) {
			my $offset;
			if ($arg =~ m/^\+=(.+)$/) {
				$offset = $1;
			} else {
				$offset = shift || die "+= without accompanying offset value\n";
			}
			unless ($offset =~ /^\d+$/) {
				die "+= <value> is not a number ($offset)\n";
			}
                        for (my $j=0;$j<$offset;$j++) {
                                $target = increment();
				@output = to_percent($target);
                        }
                        $operation_found = 1;
		} elsif ($arg eq '-') {
			unshift(@ARGV,1);
			unshift(@ARGV,'-=');
                } elsif ($arg =~ /^-=/) {
			my $offset;
			if ($arg =~ m/^-=(.+)$/) {
				$offset = $1;
			} else {
				$offset = shift || die "-= without accompanying offset value\n";
			}
			unless ($offset =~ /^\d+$/) {
				die "-= <value> is not a number ($offset)\n";
			}
                        for (my $j=0;$j<$offset;$j++) {
                                $target = decrement();
				@output = to_percent($target);
                        }
                        $operation_found = 1;
                } elsif ($arg =~ m/^=/) {
			my $value;
			if ($arg =~ m/^=(.+)$/) {
				$target = $1;
			} else {
				$target = shift || die "= without accompanying absolute value\n";
			}
			unless ($target =~ /^\d+$/) {
				die "= <value> is not a number ($target)\n";
			}
                        if ($target < 1) {
                                $target = set(get_min());
                        } elsif ($target > get_max()) {
                                $target = set(get_max());
                        } elsif ($target > 100) {
                                $target = set($target);
                        } else {
                                $target = set(
                                        int((get_max()*$target/100)+1)
                                );
                        }
                        @output = to_percent($target);
                        $operation_found = 1;
                } else {
			push(@output,$arg);
                }
        }
} else {
        @output = (
                '{"Backlight":{"Max":"'
                . get_max()
                . '","Current":"'
                . get_current()
                . '","Percentage","'
                .  int(get_current()/get_max()*100)
                . '%"}}'
        );
}

open(my $fh,'>',$last_file);
print $fh get_current();
close($fh);

print $_."\n" foreach(@output);
if ($silent) {
        exit();
} elsif ($notify) {
        my $concat = '';
        foreach (@output) {
                $concat .= $_;
        }
=pod
	use Gtk2::Notify -init, "Backlight";
	my $notification = Gtk2::Notify::new('Backlight', $concat, '', "notification-display-brightness");

	$notification->set_hint_string('x-canonical-private-synchronous','blc');
	$notification->set_urgency('NOTIFY_URGENCY_LOW');
	$notification->set_hint_int32('value',(split('%',$concat))[0]);
	$notification->set_timeout($duration);
	$notification->show();
	exit;
        print "notify-send --urgency=normal"
                . ' --icon="notification-display-brightness"'
		. ' --hint=string:x-canonical-private-synchronous:blc'
                . ' --expire-time=' . $duration
		. ' "Backlight"'
                . ' "' . $concat . " '" . join("','", @output) . "'\"";
        system "notify-send --urgency=normal"
                . ' --icon="notification-display-brightness"'
		. ' --hint=string:x-canonical-private-synchronous:blc'
		. ' --hint=int:value:' . (split('%',$concat))[0]
		. ' --expire-time=' . $duration
                . ' "' . $concat . "\"";
=cut

        exit();
} else {
        print foreach @output;
        print "\n";
        exit();
}