#!/usr/bin/perl

use strict;

my $variableName = shift;
if ( !$variableName ) {

  $variableName = "PATH";
}

my $home  = $ENV{HOME} || $ENV{LOGDIR} || (getpwuid($<))[7];
my $fName = "$home/.setpath.out";
if ( -e $fName ) {
  unlink ( $fName )
    or die( "Unable to unlink previous $fName file ($!)!\n" );
}

my @directories;
if ( !exists $ENV{$variableName} ) {
  print( "No variable, $variableName, in the environment. Continue [Y/n]? " );
  my $result;
  do {
    $result = <STDIN>;
    chomp( $result );
    if ( !defined($result) || lc($result) eq "n" ) {
      exit( 1 );
    }
  } while ( lc($result) ne "y" && $result ne "" );
} else {
  @directories = split( /:/, $ENV{$variableName} );
}

my $dirty = 0;
while( 1 ) {
  print( "Your current $variableName contains:\n" );
  
  for ( my $i = 0; $i < scalar(@directories); ++$i ) {
    my $directory = $directories[ $i ];
    my $state    = "on";
    if ( $directory =~ /\.off$/ ) {
      $state = "off";
      $directory =~ s/\.off$//;
    }

    printf( " %2d) [%3s] %s\n", $i, $state, $directory );
  }

  print( 
'-----
Enter:
 t<n> to toggle a directory on/off,
 [a|A]<directory> to add a new directory (to front|end)
 q to quit.
> ' );

  my $commandLine = <STDIN>;
  if ( !defined($commandLine) ) {
    exit( 1 );
  }
  chomp( $commandLine );
  $commandLine =~ /(.)(.*)/;
  my ($command, $args) = ($1, $2);

  if ( $command eq "t" ) {
    if ( !defined($args) || $args eq "" || 
         $args >= scalar(@directories) || $args < 0 ) {
      print( "$args is not a valid directory number (0 .. ", scalar(@directories), ")\n\n" );
    } else {
      $dirty = 1;
      if ( $directories[ $args ] =~ /\.off$/ ) {
        $directories[ $args ] =~ s/\.off$//;
      } else {
        $directories[ $args ] .= ".off";
      }
      print( "\n" );
    }
  } elsif ( $command eq "A" ) {
    push( @directories, $args );
    $dirty = 1;
  } elsif ( $command eq "a" ) {
    splice( @directories, 0, 0, $args );
    $dirty = 1;
  } elsif ( $command eq "q" ) {
    if ( $dirty ) {
      open( OUT, "> $fName" ) 
        or die( "Unable to open $fName for writing ($!)!\n" );
      print OUT ("export $variableName=", join(":", @directories), "\n");
      close( OUT );
      exit 0;
    } else {
      print( "No changes made to $variableName.\n" );
      exit( 1 );
    }
  }
}

##</code><code>##

function setpath { /fully/qualified/path/to/setpath.pl "$1"; if [ $? == 0 ]; then . $HOME/.setpath.out; echo "$1 updated."; fi };