#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dumper;

unless (exists $ENV{'WAYLAND_DISPLAY'}) {
    die "Not running in WAYLAND";
}

my $app = {};
$app->{'displays'} = {};

get_display_info($app);
show_debug(Data::Dumper->Dump([$app]));
my $wlr_line = get_wlr_line($app);

print "${wlr_line}\n";

# -----------
# Subroutines
# -----------
sub get_display_info {
    my ($app) = @_;

    open (my $RANDRH, "wlr-randr |") or die "Couldn't run wlr-randr";
    my @lines = map { chomp(); $_ } <$RANDRH>;
    close ($RANDRH);

    my $state = "IDLE";
    my $curr_disp = "UNDEF";
    my $disp_info = {};

    foreach my $ln (@lines) {
        if (my ($dn, $dd) = $ln =~ /^(\S+)\s+"([^"]+)"$/) {
            $state = "IN_DISP";

            unless (exists $disp_info->{$dn}) {
                $disp_info->{$dn} = {};
                $disp_info->{$dn}->{'name'} = $dn;
                $curr_disp = $dn;

                $disp_info->{$dn}->{'desc'} = $dd;

            }
        }
        if (($state eq "IN_DISP") || ($state eq "IN_MODES")) {
            if (my ($k,$v) = $ln =~ /\s+(\w+)\s*:\s*(.*)?$/) {
                if ($k eq "Modes") {
                    $state = "IN_MODES";
                    $disp_info->{$curr_disp}->{'modes'} = [];
                } else {
                    $disp_info->{$curr_disp}->{$k} = $v;
                    $state = "IN_DISP"
                }
            }
        }
        if ($state eq "IN_MODES") {
            if (my ($mode_string) = $ln =~ /\s+(.+)$/) {
                # 1920x1080 px, 60.000999 Hz (preferred, current)
                my ($h, $v, $f, $a) = $mode_string =~ /(\d+)x(\d+)\s*px,\s*(\S+)\s*Hz\s*\((.*)\)$/;
                my $mode_info = {};
                $mode_info->{'horizontal'} = $h;
                $mode_info->{'vertical'} = $v;
                $mode_info->{'refresh_freq'} = $f;
                if (defined $a) {
                    $mode_info->{'attributes'} = [split (/\s*,\s*/, $a)];
                    if ($a =~ /current/) {
                        $disp_info->{$curr_disp}->{'current_mode'} = $mode_info;
                    }
                    if ($a =~ /preferred/) {
                        $disp_info->{$curr_disp}->{'preferred_mode'} = $mode_info;
                    }
                }

                push(@{$disp_info->{$curr_disp}->{'modes'}}, $mode_info);

            }
        }
        # show_debug("$state: $ln");
    }

    $app->{'displays'} = $disp_info;
}

# -----------
sub get_wlr_line {
    my ($app) = @_;

    my $wlr_line = "UNKNOWN";

    my $num_disps = scalar(keys(%{$app->{'displays'}}));
    if ($num_disps == 1) {
        show_debug("Single display configuration");
        $wlr_line = "wlr-randr --output HDMI-A-1 --off --output eDP-1 --on --pos 0,0"
    } elsif ($num_disps > 1) {
        # Determine setup (Custom)
        #
        #   - Den room (DELL 27" monitor on the left of laptop display)
        my $matching_disps = has_display_with_name($app, "DELL U27");
        if (scalar (@{$matching_disps}) == 1) {
            my ($h, $v) = get_display_current_dimensions($app, $matching_disps->[0]);
            my $disp_name = $matching_disps->[0]->{'name'};
            show_debug("Multiple display configuration: Den room");

            $wlr_line = "wlr-randr --output ${disp_name} --on --pos 0,0 --output eDP-1 --on --pos ${h},0";
        }

        #
        #   - Media room (DELL 24" monitor above laptop display)
        $matching_disps = has_display_with_name($app, "DELL U24");
        if (scalar (@{$matching_disps}) == 1) {
            my ($h, $v) = get_display_current_dimensions($app, $matching_disps->[0]);
            my $disp_name = $matching_disps->[0]->{'name'};
            show_debug("Multiple display configuration: Media room");

            $wlr_line = "wlr-randr --output ${disp_name} --on --pos 0,0 --output eDP-1 --on --pos 0,${v}";
        }
    } else {
        show_debug("No displays?!");
    }

    return $wlr_line;
}

# -----------
sub has_display_with_name {
    my ($app, $name) = @_;
    my $found = [];

    foreach my $k (keys %{$app->{'displays'}}) {
        if ($app->{'displays'}->{$k}->{'desc'} =~ /$name/) {
            push(@{$found}, $app->{'displays'}->{$k});
        }
    }

    return $found;
}

# -----------
sub get_display_current_dimensions {
    my ($app, $disp) = @_;

    return ($disp->{'current_mode'}->{'horizontal'}, $disp->{'current_mode'}->{'vertical'});
}

# -----------
sub show_debug {
    my ($str) = @_;
    # UNCOMMENT TO DEBUG # print "[DEBUG] $str\n";
}