#!/usr/bin/perl -w
use strict;

if($#ARGV < 2) {
	printf("Usage: replacement regexp replacement files...\n");
	printf("Example: replacement '#000000' '#AAAAAA' *.html\n");
	exit 0;
}

my $regexp = $ARGV[0];
my $replacement = $ARGV[1];

shift @ARGV;
shift @ARGV;

for(my $i = 0; $i <= $#ARGV; ++$i) {
	my $file = $ARGV[$i];
	my $tmpfile = $file.".substitute.tmp";
	my $changed = 0;
	open(IN, $file) or die "$file: cannot open";
	open(OUT, "> $tmpfile") or die "$tmpfile: cannot open";
	while(<IN>) {
		my $prev = $_;
		if(s/$regexp/$replacement/g) {
			$changed = 1;
		}
		print OUT;
	}
	close(OUT) or die "$tmpfile: cannot close";
	close(IN) or die "$file: cannot close";
	if($changed) {
		printf("%s\n", $file);
		rename($tmpfile, $file) or die "$tmpfile: cannot rename";
	} else {
		unlink($tmpfile) or die "$tmpfile: cannot unlink";
	}
}