From 3a3bfcd6a63a0775e9ff3ee1c989b7692e963019 Mon Sep 17 00:00:00 2001
From: John Mertz <git@john.me.tz>
Date: Fri, 2 Sep 2022 22:47:44 -0600
Subject: [PATCH] Enhance kdb_backlight with sleep/restore function

---
 thinkpad/kbd_backlight.pl | 88 +++++++++++++++++++++++++++------------
 1 file changed, 62 insertions(+), 26 deletions(-)

diff --git a/thinkpad/kbd_backlight.pl b/thinkpad/kbd_backlight.pl
index fdb62cb..0a4a852 100755
--- a/thinkpad/kbd_backlight.pl
+++ b/thinkpad/kbd_backlight.pl
@@ -3,35 +3,71 @@
 use strict;
 use warnings;
 
-my $maxfile = "/sys/class/leds/tpacpi\:\:kbd_backlight/max_brightness";
-my $current = "/sys/class/leds/tpacpi\:\:kbd_backlight/brightness";
+our $maxfile = "/sys/class/leds/tpacpi\:\:kbd_backlight/max_brightness";
+our $current = "/sys/class/leds/tpacpi\:\:kbd_backlight/brightness";
+our $sleepfile = "$ENV{HOME}/.spool/kbd_sleep";
 
-my ($max, $now, $new);
-if (open(my $m, '<', $maxfile)) {
-        $max = readline($m);
-        chomp $max;
-        close($m);
-} else {
-        print "Failed to read $maxfile\n";
-        exit;
+sub readFile
+{
+        my $file = shift;
+        my $ret;
+        if (open(my $fh, '<', $file)) {
+                $ret = readline($fh);
+                chomp $ret;
+                close($fh);
+        } else {
+                die "Failed to read $file: $?\n";
+        }
+        return $ret;
 }
 
-if (open(my $c, '<', $current)) {
-        $now = readline($c);
-        chomp $now;
-        close($c);
-} else {
-        print "Failed to read $current\n";
-        exit;
+
+sub writeFile
+{
+        my ($file, $value) = @_;
+        if (open(my $fh, '>', $file)) {
+                print $fh $value;
+                close($fh);
+        } else {
+                die "Failed to write $current\n";
+        }
 }
 
-if (open(my $fh, '>', $current)) {
-        $new = (($now+1) % ($max+1));
-        chomp $new;
-        print $fh $new;
-        close($fh);
-} else {
-        print "Failed to write $current\n";
-        exit;
+sub sleepFile
+{
+        my $now = readFile($current);
+        writeFile($sleepfile,$now);
+        writeFile($current,0);
 }
-#print STDERR "$new\n";
+
+sub restoreFile
+{
+        unless (-e $sleepfile) {
+                die "Missing '$sleepfile'. Must not have slept prior to restore.\n"
+        }
+        my $value = readFile($sleepfile);
+        writeFile($current,$value);
+        unlink($sleepfile);
+}
+
+sub rotateFile
+{
+        my $max = readFile($maxfile);
+        my $now = readFile($current);
+        my $new = (($now+1) % ($max+1));
+        writeFile($current,$new);
+}
+
+if (defined($ARGV[0])) {
+        if ($ARGV[0] eq 'sleep') {
+                sleepFile();
+                exit(0);
+        } elsif ($ARGV[0] eq 'restore') {
+                restoreFile();
+                exit(0);
+        } elsif ($ARGV[0] ne 'rotate') {
+                die "Invalid mode '".$ARGV[0]."'. 'rotate', 'sleep', or 'restore'\n";
+        }
+}
+
+rotateFile();