#!/usr/bin/perl
# battstat[.pl]
# ACPI Battery Monitor
#
# version 1.0
use strict;
use POSIX qw/floor/;
#use warnings;

my $path="/proc/acpi/battery/BAT1";

die "Cannot find battery information. Perhaps ACPI is not enabled?\n"
    if !-e $path;
    
# Gather information about battery
my %info;
for(qw(info state)) {
    open FILE,"<$path/$_";
    while (my $line=<FILE>) {
        my($key,$value)=$line=~/^(.+?): *(.+?)$/i;
        $value=(split / /,$value)[0];
        next if !$key;
        $info{$key}=$value;
    }
    close FILE;
}

# Calculations
my $rc=$info{"remaining capacity"};
my $lfc=$info{"last full capacity"};
my $pr=$info{"present rate"};
my $cs=$info{"charging state"};

my($remaining,$t);
if ($cs eq "charging") {
    $remaining=floor(100-($lfc-$rc)/$lfc*100);
    $t=floor(($lfc-$rc)/$pr*3600) if $pr;
}    
else {
    $remaining=floor($rc/$lfc*100);
    $t=floor($rc/$pr*3600) if $pr;
}
$t=0 if !$pr;

# Format time
my $h=floor($t/3600); $t-=$h*3600;
my $m=floor($t/60); $t-=$m*60;
my $s=$t;
my $time_format=$h."h".$m."m".$s."s";

my $str=($cs eq "discharging") ?
    "Battery status: $remaining% remaining ($time_format)" :
	"Battery charging: $remaining% ($time_format)";
    
print "$str\n";