#!/usr/bin/perl

my $help = <<'END_HELP';
 Sampling tool File Renamer
 usage: renamer.pl DIR SEARCHREGEX REPLACEREGEX DOIT

 for every regular file in DIR, sorted by mtime,
 replaces the SEARCHREGEX with REPLACEREGEX in every filename.
 Does NOT rename anything unless DOIT!

 Special Variables are:
 %NR% - the index number for the file with the current sorting

 no captures support in regex :(
END_HELP


use strict;
use warnings;

use Data::Dumper qw(Dumper);
use POSIX qw(strftime);
use Cwd;
use File::stat;

my $dir = "-?";
$dir = $ARGV[0];
my $regexSearch = $ARGV[1];
my $regexReplace = $ARGV[2];
my $reallyDoIt = $ARGV[3];

if ($dir eq "-?") {
  usage();
}

if(!$dir) {
  print "Error: Need a directory.\n";
  die "\n";
}
if(!$regexSearch) {
  print "Error: Need a search regex.\n";
  die "\n";
}
if(!$regexReplace) {
  print "Error: Need a replace regex.\n\n";
  die "\n";
}

chdir($dir) || die "FATAL: cant chdir";

print getcwd()."\n";

opendir( DIR, getcwd() );
my @files = readdir(DIR);
closedir(DIR);

#filter out dirs
my @filesNoDir;
foreach (@files) {
  if(! -d $_) {
    push(@filesNoDir,$_);
  }
}

@files = @filesNoDir;

my @sorted_files = sort { stat($a)->mtime <=> stat($b)->mtime } @files;

my $fname = "";
my $fstat = "";
my $mtime = "";

my $fname_new = "";
my $counter = 1;
my $regexReplaceNew = "";
my $counterFmt;
for (@sorted_files) {
  $fname = $_;
  $fstat = stat($_);
  $mtime =  strftime('%Y/%m/%d %H:%M:%S',localtime($fstat->mtime));

  $regexReplaceNew = $regexReplace;
  $counterFmt = sprintf("%03s",$counter);
  $regexReplaceNew =~ s/%NR%/$counterFmt/g;

  $fname_new = $fname;
  $fname_new =~ s/$regexSearch/$regexReplaceNew/;
#  $fname_new =~ s/(.*?)\s1-/%NR%_$1/;

  printf "%-40s%-40s%-20s\n",$fname_new,$fname,$mtime;

  if($reallyDoIt) {
    rename($fname,$fname_new);
  }

  $counter++;
}



sub usage {
  print $help;
  die "\n";
}