use warnings;
use strict;
use Tk;
use Tk::Tree;

my $rootPath = shift;

ShowHelp () if ! defined $rootPath;
ShowHelp (-2, "Error finding folder $rootPath\n\n") if ! -d $rootPath;

my $main = MainWindow->new (-title => "Folder stats for $rootPath");
my $tree = $main->ScrlTree
    (
    -font => 'FixedSys 8',
    -itemtype => 'text', -separator  => '/',
    -scrollbars => "osoe"
    );

my @pathStack = (1);
my $maxNesting = 0;
my $totalLines;
my $maxLineLength = 0;
my $currPath = join "/", @pathStack;

$tree->add ($currPath, -text => $rootPath);
my ($subDirCount, $subFileCount, $subTotalSize) = buildSubTree
  ($tree, $rootPath, \@pathStack, \$maxNesting, \$totalLines, \$maxLineLength);
my $annotation = $rootPath . " \t(";
my $plural = $subDirCount != 1 ? 's' : '';
$annotation .= $subDirCount . " dir$plural, " if $subDirCount;
$annotation .= "$subFileCount files, $subTotalSize bytes)";
$tree->entryconfigure ($currPath, -text =>  $annotation);

$totalLines = 40 if $totalLines > 40;
$main->geometry (($maxLineLength + @pathStack * 4) * 5 . 'x' . (40 + $totalLines * 20));
closeTree ($tree, '');

$tree->pack(-fill=>'both',-expand => 1);

MainLoop;

sub closeTree {
    my $tree = shift;
    my ($entryPath, $hideChildren) = @_;
    my @children = $tree->info (children => $entryPath);

    return if ! @children;

    for (@children) {
        closeTree ($tree, $_, 1);
        $tree->hide ('entry' => $_) if $hideChildren;
    }
    $tree->setmode ($entryPath, 'open') if length $entryPath;
}

sub buildSubTree {
  my ($tree, $rootPath, $pathStack, $maxNesting, $totalLines, $maxLineLength) = @_;
  my $dirCount = 0;
  my $fileCount = 0;
  my $sizeTotal = 0;
  
  push @$pathStack, 1;
  $$maxNesting = @$pathStack if $$maxNesting < @$pathStack;
  
  my $dir;
  opendir $dir, $rootPath;
  
  while (my $currDir = readdir $dir) {
    next if $currDir =~ /^\.\.?$/;
    
    my $path = "$rootPath/$currDir";
    ++$$totalLines;

    my $currPath = join "/", @$pathStack;
    my $nodeText = $path;

    $tree->add ($currPath, -text => $nodeText);

    if (-d $path) {
      my ($subDirCount, $subFileCount, $subTotalSize) = buildSubTree
        ($tree, $path, $pathStack, $maxNesting, $totalLines, $maxLineLength);
      
      $dirCount += $subDirCount + 1;
      $fileCount += $subFileCount;
      $sizeTotal += $subTotalSize;

      my $annotation = $nodeText . " \t(";
      my $plural = $subDirCount != 1 ? 's' : '';
      $annotation .= $subDirCount . " dir$plural, " if $subDirCount;
      $annotation .= "$subFileCount files, $subTotalSize bytes)";
      $tree->entryconfigure ($currPath, -text =>  $annotation);
    } else {
      my $fileSize = -s $path;
      $tree->entryconfigure ($currPath, -text => $nodeText . " ($fileSize bytes)");
      ++$fileCount;
      $sizeTotal += $fileSize;
    }
      
    $$maxLineLength = length ($nodeText) if length ($nodeText) > $$maxLineLength;
    ++$pathStack->[-1];
  }
  
  closedir $dir;
  pop @$pathStack;
  return ($dirCount, $fileCount, $sizeTotal);
  }

sub ShowHelp
{
my $exitValue = 0;
$exitValue = shift if defined $_[0] and $_[0] =~ /^[-+]?\d+$/;

print $_ while $_ = shift;

print <<HELP;
FolderStats scans a directory tree starting at the folder given on the command
line and generates an explorer like tree giving folder content stats such as
number of files, their total size, and the count and sizes of sub-folders.

Note that the statistics are not dynamically updated as files and folders are
altered on disk.

Usage:

FolderStats <root folder>

HELP

exit ($exitValue || -1);
}