#!/usr/bin/perl


=head1

Usage: rename-script [OPTIONS] PATH

Options:

  -p   Pattern to look for in file's name. Default '\s'
  -r   Replacement string. Default '_'
  -n   Don't use 'g' option modifier with pattern matching

=cut


use strict;
use File::Spec;
use File::Basename;
use File::Find;
use Getopt::Std;

my %opts;
getopts('np:r:', \%opts);

my $path = shift @ARGV // die "need path argument.\n";
my $pat = $opts{p} // '\s';
my $rep = $opts{r} // '_';
my @found;

die "bad pattern $pat\n" unless eval { "" =~ /$pat/; 1; };

find sub { unshift @found, $File::Find::name }, $path;

for ( @found ) {
  my ($base,$dir) = (basename($_),dirname($_));
  my $newbase;
  
  defined $opts{n} ? (($newbase = $base) =~ s/$pat/$rep/ ) : (($newbase = $base) =~ s/$pat/$rep/g );
  
  if ( $newbase ne $base ) {
    my $newname =  File::Spec->catfile($dir,$newbase); 
    (-e $newname) and (warn("can't rename $_ to $newname: $newname already exists\n"),next) ;
    rename($_,$newname) or warn "can't rename $_ to $newname:$!\n";
  }
}