#!/usr/bin/perl -w
$CMD='';
$HELP=0;
$YES=0;

$rename_try=0;
$rename_ok=0;
$ERR='';

while($_=shift @ARGV) {
	if(/^s([\/%]).+\1[gi]*/) {
		$CMD=$_;
	}
	elsif(/^-y/) {
		$YES=1;
	}
	else { $HELP=1 };
}

if(!defined $CMD || $CMD eq'' || $HELP) {
	print STDERR "Mass substitution rename tool. 
Usage:\n    ls *some*files* | $0 s/some/other/ [-y]
	s/some/other/	Substitution operator (sed/perl alike)
	-y		Do actual rename
\n";
	exit 64;
}

while(<STDIN>){
	chomp;
	$new=$_; eval "\$new=~$CMD";
	if($new eq $_) {
		print "# leaving $_\n";
		next;
	};
	print qq%mv "$_" "$new"\n%;
	if($YES) { 
		$rename_try++; 
		if( rename($_, $new) ){
			$rename_ok++;
		} else { 
			print "# ^^^ ERROR RENAMING \"$_\"\n";
			$ERR.=qq%Error renaming "$_" to "$new"\n%;
		}
	 };
}

my $bad=$rename_try-$rename_ok;
print STDERR "Renames done: $rename_ok", 
	$bad?", failed: $bad":'',
	"\n";

if($ERR ne''){
	print STDERR $ERR;
	exit 1;
}