#!/usr/bin/perl
#fill_player.pl
#Fill a flash device with randomly-selected songs from your collection
#Copyright Cedric Nelson, 2008
#cedric.nelson@gmail.com

use File::Find;
use File::Copy;

use strict;

my ($source_dir,
    $destination_dir,
    %music_index,
    @music_file_list,
    $music_file_count,
    $total_file_size,
    $remaining,
    $percent_used,
    $random_file_index,
    $random_file_size,
    @transfer_list,
    $transfer_file_count);

$source_dir = '/home/cedric/Music';
($destination_dir) = @ARGV;
unless ($destination_dir) {$destination_dir = '/media/S3/Music';}

#Build music file index
find(\&index_files, $source_dir);
while (my ($file, $size) = each %music_index) {
  if ($file =~ /\.mp3$/) {
    push @music_file_list, $file;
    $total_file_size += $size;
  }
}

$music_file_count = @music_file_list;
($remaining, $percent_used) = calculate_free($destination_dir);

print "Source dir: $source_dir\nFile count: $music_file_count\nTotal f
+ile size (KB): $total_file_size\n\n";
print "Destination dir: $destination_dir\nPercent used: $percent_used\
+nRemaining space (KB): $remaining\n\n\n";

#Generate list of randomly-selected files
until ($music_file_count == 0) {
  $random_file_index = int(rand($music_file_count + 1));
  $random_file_size = $music_index{$music_file_list[$random_file_index
+]};  
  if ($music_file_list[$random_file_index] && $random_file_size < $rem
+aining) {
    ##print "Selected file: $random_file_index, $music_file_list[$rand
+om_file_index], $random_file_size\n";
    push @transfer_list, (splice @music_file_list, $random_file_index,
+ 1);
    $remaining -= $random_file_size;
    ##print "Estimated remaining: $remaining\n";
    $music_file_count = @music_file_list;
  }
  else {
    splice @music_file_list, $random_file_index, 1;
    $music_file_count = @music_file_list;
  }
}

print "Random playlist:\n";
for (@transfer_list) {
  print "$_\n";
}
$transfer_file_count = @transfer_list;
print "Total: $transfer_file_count\n";
print "Estimated remaining space (KB): $remaining\n\n\n";

#Copy files to media player
print "Copying...\n";
print "Used\tFiles\tRemaining space (KB)\n";
until ($transfer_file_count == 0) {
  my $file = shift @transfer_list;
  $transfer_file_count = @transfer_list;
  copy("$file","$destination_dir/$_") or warn "Copy failed: $!";
  ($remaining, $percent_used) = calculate_free($destination_dir);
  print "$percent_used\t$transfer_file_count\t$remaining\n";
}
print "Done.\n";

sub calculate_free {
  my ($dir) = @_;
  my ($free_space,
      @free_space,
      $used_percent);
  
  $free_space = `df $dir`;
  @free_space = split /\n/, $free_space;
  shift @free_space;
  $free_space = shift @free_space;
  #Example output:
  #/dev/sdc1              3889424   1869992   2019432  49% /media/S3
  @free_space = split /\s+/, $free_space;
  $free_space = $free_space[3];
  $used_percent = $free_space[4];
  #Returned value is in KB
  return ($free_space, $used_percent); 
}

sub index_files {
  #Filesize is returned in bytes
  my $filesize = -s "$File::Find::name";
  $filesize = int($filesize / 1024);
  unless ($music_index{$File::Find::name}) {$music_index{$File::Find::
+name} = $filesize;}
}