#!/usr/bin/perl -w
# Copyright © 2001, 2002, 2003 Jamie Zawinski <jwz@jwz.org>.
#
# Permission to use, copy, modify, distribute, and sell this software and its
# documentation for any purpose is hereby granted without fee, provided that
# the above copyright notice appear in all copies and that both that
# copyright notice and this permission notice appear in supporting
# documentation.  No representations are made about the suitability of this
# software for any purpose.  It is provided "as is" without express or 
# implied warranty.
#
# This program attempts to locate a random image from the specified directory,
# and load it on to the root window, using some other program that can decode
# image files.  (It attempts to find such a program.)
#
# The various xscreensaver hacks that manipulate images ("slidescreen",
# "jigsaw", etc.) get the image to manipulate by running the
# "xscreensaver-getimage" program.
#
# "xscreensaver-getimage" will invoke this program, depending on the
# value of the "chooseRandomImages" and "imageDirectory" settings in
# the ~/.xscreensaver file (or /usr/lib/X11/app-defaults/XScreenSaver).
#
# Created: 12-Apr-01.

require 5;
use diagnostics;
use strict;

use POSIX;
use Fcntl;

# Apparently the "old way" to get S_ISLNK and friends is to do this:
#
use POSIX ':fcntl_h';

# But apparently the "new way" is to do this:
#
#  use Fcntl ':mode';
#
# but of course that will generate an error on "old" (pre-5.6?) Perl versions.
# So we do it like this instead:
#
BEGIN {
  if (! defined(&S_ISLNK)) {  # perhaps defined by "POSIX"?
    require Fcntl;
    import  Fcntl ':mode';    # if not, look for it in "Fcntl".
  }
}


my $progname = $0; $progname =~ s@.*/@@g;
my $version = q{ $Revision: 1.11 $ }; $version =~ s/^[^0-9]+([0-9.]+).*$/$1/;

my $verbose = 0;

# These are programs that can be used to put an image file on the root
# window (including virtual root windows.)  The first one of these programs
# that exists on $PATH will be used (with the file name as the last arg.)
#
# If you add other programs to this list, please let me know!
#
my @programs = (
  "chbg       -once -xscreensaver -max_grow 4 -max_size 100",
  "xv         -root -quit -viewonly -maxpect +noresetroot -quick24 -rmode 5" .
  "           -rfg black -rbg black",
  "xli        -quiet -fullscreen -onroot -center -border black",
  "xloadimage -quiet -fullscreen -onroot -center -border black",

# this lame program wasn't built with vroot.h:
# "xsri       -scale -keep-aspect -center-horizontal -center-vertical",
);

sub pick_displayer {
  my @names = ();

  foreach my $cmd (@programs) {
    $_ = $cmd;
    my ($name) = m/^([^ ]+)/;
    push @names, "\"$name\"";
    print STDERR "$progname: looking for $name...\n" if ($verbose > 2);
    foreach my $dir (split (/:/, $ENV{PATH})) {
      print STDERR "$progname:   checking $dir/$name\n" if ($verbose > 3);
      return $cmd if (-x "$dir/$name");
    }
  }

  $names[$#names] = "or " . $names[$#names];
  printf STDERR "$progname: none of: " . join (", ", @names) .
                " were found on \$PATH.\n";
  exit 1;
}


my @all_files = ();
my %seen_inodes;

sub find_all_files {
  my ($dir) = @_;

  print STDERR "$progname: reading dir $dir/...\n" if ($verbose > 2);

  local *DIR;
  if (! opendir (DIR, $dir)) {
    print STDERR "$progname: couldn't open $dir: $!\n" if ($verbose);
    return;
  }
  my @files = readdir (DIR);
  closedir (DIR);

  my @dirs = ();

  foreach my $file (@files) {
    next if ($file =~ m/^\./);      # ignore dot files
    next if ($file =~ m/[~%\#]$/);  # ignore backup files
    next if ($file =~ m/\.(BAK|bak|tmp|orig|rej|rpmsave)$/);
    next if ($file eq "core");

    $file = "$dir/$file";
    my @st = stat($file);
    my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
        $atime,$mtime,$ctime,$blksize,$blocks) = @st;

    if ($#st == -1) {
      if ($verbose) {
        my $ll = readlink $file;
        if (defined ($ll)) {
          print STDERR "$progname: dangling symlink: $file -> $ll\n";
        } else {
          print STDERR "$progname: unreadable: $file\n";
        }
      }
      next;
    }

    next if ($seen_inodes{$ino}); # break symlink loops
    $seen_inodes{$ino} = 1;

    if (S_ISDIR($mode)) {
      push @dirs, $file;
      print STDERR "$progname:   found dir  $file\n" if ($verbose > 2);
    } elsif (S_ISREG($mode) || S_ISLNK($mode)) {
      push @all_files, $file;
      print STDERR "$progname:   found file $file\n" if ($verbose > 2);
    } elsif ($verbose > 2) {
      print STDERR "$progname:   nonreg $file\n";
    }
  }

  foreach (@dirs) {
    find_all_files ($_);
  }
}


sub find_random_file {
  my ($dir) = @_;

  $dir =~ s@/+$@@g;

  print STDERR "$progname: recursively reading $dir...\n" if ($verbose > 1);
  find_all_files ($dir);
  print STDERR "$progname: found " . ($#all_files+1) . " files\n"
    if ($verbose > 1);

  @all_files = sort(@all_files);

  if ($#all_files < 0) {
    print STDERR "$progname: no files in $dir\n";
    exit 1;
  }

  my $n = int (rand ($#all_files + 1));
  my $file = $all_files[$n];

  print STDERR "$progname: chose file $n: $file\n" if ($verbose > 1);
  return $file;
}



sub display_file {
  my ($file, $displayer) = @_;

  if (!defined($displayer)) {
    print STDOUT "$file\n";
  }  else {
    my @cmd = split (/ +/, $displayer);
    push @cmd, $file;   # do it this way to allow file names with spaces.
    print STDERR "$progname: executing \"" . join(" ", @cmd) . "\"\n"
      if ($verbose);
    exec (@cmd) || die;
  }
}


sub find_and_display {
  my ($dir, $displayer) = @_;
  my $file = find_random_file ($dir);
  display_file ($file, $displayer);
}


sub usage {
  print STDERR "usage: $progname [--verbose] [--name] directory\n";
  print STDERR "Puts a randomly selected image on the root window.\n";
  print STDERR "With --name, merely prints the filename to stdout.\n";
  exit 1;
}

sub main {
  my $dir = undef;
  my $do_name = 0;

  while ($_ = $ARGV[0]) {
    shift @ARGV;
    if ($_ eq "--verbose") { $verbose++; }
    elsif (m/^-v+$/) { $verbose += length($_)-1; }
    elsif ($_ eq "--name") { $do_name++; }
    elsif (m/^-./) { usage; }
    elsif (!defined($dir)) { $dir = $_; }
    else { usage; }
  }

  usage unless (defined($dir));
  my $displayer = undef;

  $displayer = pick_displayer() unless $do_name;

  if (-d $dir) {
    find_and_display ($dir, $displayer);
  } elsif (-f $dir) {
    display_file ($dir, $displayer);
  } else {
    usage();
  }
}

main;
exit 0;