#!/usr/bin/perl

use strict;

my $numToKeep = shift || die "Usage: $0 <number of backups> <directory>\n";
my $dir       = shift || die "Usage: $0 <number of backups> <directory>\n";
my $lookfor   = '(?:journal|checkpoint)';

# Grab the files we want. 
opendir( D, $dir ) or die "can't open $dir: $!\n";
my @files = grep /\A$lookfor\.\d+\.gz\Z/ => readdir D;
closedir D or die;

chdir $dir or die "can't open $dir: $!\n";

my @journals    = sort by_num grep /^journal/    => @files;
my @checkpoints = sort by_num grep /^checkpoint/ => @files;

if ( @journals > $numToKeep ) {
  splice( @journals,    -$numToKeep );
  my $numj  = unlink @journals;
  warn "Not all journals were deleted: (" . join(" ", @journals) . ") $!\n"    if $numj != @journals;
}
if ( @checkpoints > $numToKeep ) {
  splice( @checkpoints, -$numToKeep );
  my $numc  = unlink @checkpoints;
  warn "Not all checkpoints were deleted: (" . join(" ", @checkpoints) . ") $!\n" if $numc != @checkpoints;
}

sub by_num { 
  my $numa = $a;
  my $numb = $b;
  $numa =~ s/[^\d+]//g;
  $numb =~ s/[^\d+]//g;
  return $numa <=> $numb;
}