#! /usr/bin/perl


if(@ARGV != 4) {
	die <<EOHELP;
usage: complete_data.pl datafile x_step y_step z_step > output.data

This program converts the three column output of a postgres query
(which returns 3 columns) into a format suitable for being used as
gnuplot data. You'll want to use a set of commands something like:

set pm3d map
set terminal png truecolor size 800,600
set output "/tmp/gnuplot.png"
splot "/tmp/input.data" with pm3d

EOHELP
}

use strict;

my ($datafile, $x_step, $y_step, $z_step) = @ARGV;

open(my $df, "<", $datafile);

my %data;

# read the data
foreach my $line (<$df>) {
	if($line =~ m{(\d+\.?\d*).*?[, |](\d+\.?\d*).*?[, |](\d+\.?\d*)}) {
	   $data{$1}->{$2} = $3;
   }
}


# calculate the ranges
#
# note: yes, the min is cheating, but it works for pretty much any
# reasonable data set. More properly, I should just check for null as
# a special case (or alternatively, initialize with any random value
# from the set), but this is already coded and works, and this program
# is mostly just a quick hack anyhow.
my ($x_min, $x_max, $y_min, $y_max) = (2**30, 0, 2**30, 0);
foreach my $xkey (keys %data) {
	$x_min = min($xkey, $x_min);
	$x_max = max($xkey, $x_max);
	foreach my $ykey (keys %{$data{$xkey}||{}}) {
		$y_min = min($ykey, $y_min);
		$y_max = max($ykey, $y_max);
	}
}


# print out the complete data
foreach my $x ($x_min..$x_max) {
	for(my $y = $y_min; $y <= $y_max; $y += $y_step) {
		print "$x $y " . ($data{$x}->{$y} + 0) . "\n";
	}
	print "\n";
}



sub min {
	return $_[0] > $_[1] ? $_[1] : $_[0];
}

sub max {
	return $_[0] > $_[1] ? $_[0] : $_[1];
}