#!/usr/bin/perl

use warnings FATAL => 'all';
use strict;

use Data::Dumper;

# turn on autoflush
$| = 1;

sub booleq {
    my ($s) = @_;
    return sub { return $_[0] eq $s };
}

sub boolne {
    my ($s) = @_;
    return sub { return $_[0] ne $s };
}

sub numwh {
    my ($s) = @_;
    my ($n) = $s =~ m/^(.*) Wh$/;
    return $n;
}

sub htime {
    my ($s) = @_;
    if ($s =~ m/^([0-9.]+) hours$/) {
        return int($1 * 60);
    } elsif ($s =~ m/^([0-9.]+) minutes$/) {
        return int($1);
    } else {
        die "unknown time: $s";
    }
}

sub stime {
    my ($n) = @_;
    my $h = $n / 60;
    my $m = $n % 60;
    return sprintf("%02d:%02d", $h, $m);
}

sub perc {
    my ($n, $d) = @_;
    return sprintf("%.1f%%", $n * 100 / $d);
}

sub charge_time {
    my ($data) = @_;
    return "--:--" if $data->{full} || $data->{tcharge} == 0;
    return stime($data->{tcharge});
}

sub drain_time { 
    my ($data) = @_;
    return "--:--" if $data->{tdrain} == 0;
    return stime($data->{tdrain});
}

sub main {
    if (@ARGV) {
        my $t = $ARGV[0];
        # require a positive number of seconds (e.g. 2, 4.5, 0.2, ...)
        unless ($t =~ m/^([1-9][0-9]*(\.[0-9]+)?|0\.[0-9]*[1-9][0-9]*)$/) {
            print "usage: $0 [POLL-SECS]\n";
            exit(1);
        }
        do {
            run();
            select(undef, undef, undef, $t);
        } while (999);
    } else {
        run();
    }
}

sub run {
    my $data = init();
    #print Dumper($data) . "\n";
    display1($data, 5);
}

sub mac_meta {
    return (
        "ExternalConnected" => [["connected", booleq("Yes")]],
        "AvgTimeToEmpty" => [["tdrain", \&int]],
        "AvgTimeToFull" => [["tcharge", \&int]],
        "MaxCapacity" => [["max", \&int]],
        "CurrentCapacity" => [["cur", \&int]],
        "FullyCharged" => [["full", booleq("Yes")]],
        "IsCharging" => [["charging", booleq("Yes")]],
    );
}

sub linux_meta {
    return (
        "energy" => [["cur", \&numwh]],
        "energy-full" => [["max", \&numwh]],
        "time to empty" => [["tdrain", \&htime]],
        "time to full" => [["tcharge", \&htime]],
        "state" => [
            ["connected", boolne("discharging")],
            ["full", booleq("fully-charged")],
        ],
    )
}

my $is_linux = $^O eq "linux";

my %meta = $is_linux ? linux_meta() : mac_meta();

sub mac_cmd {
    return "ioreg -rc AppleSmartBattery";
}

sub mac_re {
    return qr/^ *"(\w+)" = (.+)$/;
}

sub linux_cmd {
    return "upower -i `upower -e | grep battery`";
}

sub linux_re {
    return qr/^ *([^:]+): +(.+)$/;
}

sub init {
    my $data = {};
    $data->{tcharge} = 0;
    my $cmd = $is_linux ? linux_cmd() : mac_cmd();
    open(my $fh, "-|", $cmd);
    my $re = $is_linux ? linux_re() : mac_re();
    while (my $line = <$fh>) {
        my ($key, $val) = $line =~ m/$re/;
        next unless $key && $val;
        my $r = $meta{$key};
        next unless $r;
        for my $p (@$r) {
            $data->{$p->[0]} = $p->[1]->($val);
        }
    }
    return $data;
}

sub icon {
    my ($data) = @_;
    return $data->{full} ? "☀" : "⚡" if $data->{connected};
    return $data->{tdrain} < 30 ? "⚠" : "⌸";
}

sub display1 {
    my ($data, $n) = @_;
    my $c = $data->{connected};
    my $p = perc($data->{cur}, $data->{max});
    my $icon = icon($data);
    my $f = $c ? \&charge_time : \&drain_time;
    my $t = $f->($data);
    printf("$icon %s (%s)\n", $t, $p);
}

main();