Simple script for updating Cinnamon wallpapers

change-wallpaper.pl

#!/usr/bin/env perl
# Change Cinnamon desktop background.
# USAGE: change-wallpaper.pl $HOME/Pictures/Wallpapers/...

# change-wallpaper - update Cinnamon wallpapers
# Copyright (c) 2016 Ben Moon
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

my $USAGE = "USAGE: change-wallpaper.pl file";

sub exit_usage {
    print "$USAGE\n" and exit 1;
}

my @cs = @ARGV;
exit_usage if @cs == 0;

my $walldir = "$ENV{HOME}/.wallpapers";
mkdir $walldir unless -d $walldir;
# Initialize wallpaper info (track current and next wallpaper)
my $finfo_path = "$walldir/.wall-info";
unless (-f $finfo_path) {
    open my $fh, '>', $finfo_path;
    print $fh "";
}

sub update_wall_info {
    my $current = shift;
    open my $fh, '>', $finfo_path;
    print $fh "$current\n";
}

sub update_wallpaper {
    my $path = shift;
    print STDERR "no such file $path\n" and exit 1 unless -f $path;
    `gsettings set org.cinnamon.desktop.background picture-uri "file://$path"`
}

sub next_wallpaper {
    my $paper_info = do { open my $fh, '<', $finfo_path; <$fh>; };
    chomp (my $current = $paper_info);
    my @papers = glob "$walldir/*";
    my @sorted = sort @papers;
    if ($current eq '' || $current eq $sorted[$#sorted]) {
        $current = $sorted[0];
    } else {
        while (my $path = shift @sorted) {
            if ($path eq $current) {
                $current = shift @sorted;
                last;
            }
        }
    }
    update_wallpaper($current);
    update_wall_info($current);
}

while (my $command = shift @cs) {
    if ($command =~ /^-(n|-next)$/i) {
        next_wallpaper();
        exit;
    }
    # Load all specified files (glob) into the .wallpapers directory
    if ($command =~ /^(-lw|--load-wallpapers)$/i) {
        my @files = @cs;
        # my $load_path = shift @cs or exit_usage;
        # my @files = glob $load_path;
        foreach my $file (@files) {
            my $base = `basename $file`;
            `cp $file $walldir/$base`;
        }
        exit;
    }
    exit_usage if @cs > 1;
    update_wallpaper($command);
}