#!/usr/bin/perl -w
use strict;
use diagnostics;
# Indent code. Handy for finding nesting errors,
# and for autoindenting stuff from the forum.
# Bugs: doesn't even attempt to match tokens.

# Create hashes of valid in/outdenting strings. 
# 1-Takes effect this line
# 2-Takes effect next line
my %incommands=('FUNCTION'=>2,'WHILE'=>2,'REPEAT'=>2,
     'IF'=>2,'ELSE'=>2,'FOR'=>2,'DO'=>2);
# Create an array of valid unindenting strings.
my %outcommands=('ENDFUNCTION'=>1,'ENDWHILE'=>1,'UNTIL'=>1,
     'ELSE'=>1,'ENDIF'=>1,'THEN'=>2,'NEXT'=>1,'LOOP'=>1);

# Not dealt with/special cases.
# 'REMSTART', '<label:>','REMEND','RETURN',

my $indentThis=0;
my $indentNext=0;
my $workString='';
my $printString='';
my $inRem=0;
# Parse the input.
while (<>) {
 ($workString=$_) =~ s/\s*$//; # Remove trailing whitespace so can detect last character.
 ($workString=$_) =~ s/^\s*//; # Remove leading whitespace.
 if ($workString eq '') {print ; next;} #Ignore blank lines.
 $printString = $workString;

 # Remove comments, since they do not feature in our calculations.
 $workString =~ s/REMSTART.*?REMEND//ig; # remstart/remend pairs.
 if ($inRem) {
  if ($workString =~ s/.*REMEND//i) { $inRem=0 }
  else { $workString="" }
 }
 if ($workString =~ s/REMSTART.*//i) { $inRem=1 }
 $workString =~ s/\`.*//;
 $workString =~ s/REM.*//i;

 # Keywords.
 foreach (split /\W/, uc($workString)) {
  # A command (like else) can be in BOTH simultaneously.
  if (defined($incommands{$_})) {
# print "BINGO!!! $_\n";
   $indentThis++ if $incommands{$_}==1;
   $indentNext++;
  }
  if (defined($outcommands{$_})) {
# print "BONGO!!! $_\n";
   $indentThis-- if $outcommands{$_}==1;
   $indentNext--;
  }
 }
 $printString = (" " x $indentThis).$printString;
 print $printString;

 $indentThis=$indentNext;
}