#!/usr/bin/perl

use strict;
use RRDs;

sub usage {
	print("usage: mvrrd.pl src.rrd dst.rrd start end\n");
}

usage() if scalar(@ARGV) != 4;

my $src = @ARGV[0];
my $dst = @ARGV[1];
my $start = $ARGV[2];
my $end = $ARGV[3];

sub RRDupdate {
	my $time = shift;
	my $val = shift;

	my @arg = ();

	push @arg, $dst;
	push @arg, "$time:$val";
	RRDs::update(@arg);
	my $error = RRDs::error;
	die "RRD error: $error\n" if $error;
}

my @arg = ();
push @arg, "$src";
push @arg, "AVERAGE";
push @arg, "--start", $start;
push @arg, "--end", $end;

my ($dataStart,$step,$names,$data) = RRDs::fetch(@arg);
my $error = RRDs::error;
die "RRD error: $error\n" if $error;
print "Start:       ", scalar localtime($dataStart), " ($dataStart)\n";
print "Step size:   $step seconds\n";
print "DS names:    ", join (", ", @$names)."\n";
print "Data points: ", $#$data + 1, "\n";
print "Data:\n";
for my $line (@$data) {
#	print "  ", scalar localtime($dataStart), " ($dataStart) ";
	my ($sec, $min, $hour, $mday, $mon, $year) = localtime($dataStart);
	my $isoDate = sprintf("%04d%02d%02d", $year + 1900, $mon + 1, $mday);
	for my $val (@$line) {
#		printf "%f ", $val;
		$val = 'U' if !defined $val;
#		print "val: $val @ time $isoDate";
#		print " ... Updating dst";
		RRDupdate($dataStart, $val);
	}
	$dataStart += $step;
#	print "\n";
}