#!/usr/bin/perl

use warnings;

use HTML::Parser;

print("Enter an html file (with either a .html or .htm extension): ");
$file=<STDIN>;

my $file = $ARGV[0];
unless ($file) {
	print ("No filename given\n");
	exit;
}

my $new;
my $p = HTML::Parser->new(
	start_h => [ \&start_h, 'tagname, text' ],
	end_h => [\&end_h, 'tagname, text' ],
	default_h => [sub { $new .= shift }, 'text'],
);

$p->parse_file($file);

# Rename the old file
my $newfile = $file.'.old';
rename($file, $newfile) or die "Can't rename $file: $!";

# Write the new text to the old filename
open my $fh, ">", $file or die "Can't create new file: $!";
print $fh $new;
close $fh;

sub start_h {
	my($tag, $text) = @_;
	my $uc = uc $tag;
	$text =~ s/$tag/$uc/;
	$new .= $text;
}

sub end_h {
	my($tag, $text) = @_;
	my $uc = uc $tag;
	$text =~ s/$tag/$uc/;
	$new .= $text;
}