#!/usr/bin/perl -w

use strict;

#how many options should be presented at minimum?
my $minpermutelength = $ARGV[0];

#this will be set to 0..$#array_passed_in when all is working
my @slots = (0..4);

my $biggestslotnum = $#slots;

die("Minimum permute length $minpermutelength is larger than the data set of 0..$#slots\n") if ($minpermutelength > $#slots);
die("Minimum permute length cannot be negative or undefined.\n") if ($minpermutelength < 0 || !defined $minpermutelength);

my $loop = 0;
my $iteration = 0;
my $thispermute = $#slots;
while ($#slots >= $minpermutelength) {
   while ($slots[$#slots] <= $biggestslotnum) {
      for (@slots) { print "$_" }; print " loop: $loop iteration: $iteration thispermute: $thispermute\n"; # record
      $slots[$#slots]++;
   }
   $slots[$#slots]--; # fix overage from while above
   if ($slots[$#slots] == $biggestslotnum && $slots[0] == $biggestslotnum - $#slots && $loop == 0) {
      $thispermute--; # shrink permute string by one
      @slots = (0..$biggestslotnum); # reset
      splice(@slots,$thispermute-$biggestslotnum); # 0 1 2 3
      $iteration = 0;
      next;
   }
   if ($slots[$#slots-$iteration-1] == $slots[$#slots-$iteration]-1) { # 0 3 4
      $loop = 0;
      $iteration++;
      $slots[$#slots-$iteration-1]++;
      # I think my problem is in these splices, but I can't figure it out. :(
      if ($slots[$#slots-$iteration] - $slots[$#slots-$iteration-1] > 1) {
         splice(@slots,$slots[$#slots-$iteration-1],$thispermute);
         splice(@slots,@slots,0,$slots[$#slots-$iteration-1]+1..(($slots[$#slots-$iteration-1]+1)+($thispermute-@slots)));
         $slots[$#slots]++ while ($slots[$#slots] <= $slots[$#slots-1]);
         $iteration = 0;
      }
   } else {
      $loop++;
      $slots[$#slots-1]++; #increase the slot to the left by one
      $slots[$#slots] = $thispermute + $loop unless ($slots[$#slots-1] == $slots[$#slots]-1); # start counting again
      $slots[$#slots]++ while ($slots[$#slots] <= $slots[$#slots-1]);
   }
}