#!/usr/bin/perl
#
#

%expr =
    (
     'l2u' => 'tr/a-z/A-Z/',
     'u' => 'tr/a-z/A-Z/',
     'u2l' => 'tr/A-Z/a-z/',
     'l' => 'tr/A-Z/a-z/',
     'rot13' => 'tr/A-Za-z/N-ZA-Mn-za-m/',
     'sh-1' => 'tr/B-ZAb-za/A-Za-z/',
     'sh+1' => 'tr/A-Za-z/B-ZAb-za/',
     );

while (@ARGV) {
    $_ = shift(@ARGV);
    if (/^--/) {
	if (/^--$/) {
	    push(@files, @ARGV);
	    last;
	} elsif (/^--(.*)$/ && $expr{$1}) {
	    push(@expr, $expr{$1});
	}
    } elsif (/^-/) {
	$test  = 1 if (/t/);
	$force = 1 if (/f/);
	$help  = 1 if (/h/);
    } else {
	push(@files, $_);
    }
}

if (@expr == 0) {
    $op = shift(@files);
    push(@expr, $op);
}

if ($help || @files == 0) {
    die "Usage: $0 [-t|-f|-h] perlexpr [filenames]\n" ;
}

#if (!@ARGV) {
#    @ARGV = <STDIN>;
#    chop(@ARGV);
#}

foreach (@files) {
    next unless (-e $_);
    $was = $_;
    foreach $op (@expr) {
	eval $op;
    }
    die $@ if $@;
    unless ($was eq $_) {
	if ($force || !(-e $_)) {
	    rename($was, $_) unless ($test);
	    print "$was --> $_\n";
	} else {
	    print "$was --> $_ : not renamed, since file exists\n";
	}
    }
}