#!/usr/bin/perl

# wpdf -- view, watch and remake pdf based on Makefile

use strict;
use warnings;

my %deptarget; # dependency => target

# collect dependencies for given pdf files
for my $target (@ARGV) {
	if ($target =~ /\.pdf$/) {
		# try to directly parse out dependencies
		open my $f, '<', 'Makefile'
			or die "could not open Makefile: $!\n";
		while (<$f>) {
			next if not /^\Q$target\E:\s*(.*)/;
			$deptarget{$_} = $target for split /\s/, $1;
			goto found;
		}

		# try to get implicit dependencies
		(my $esc = $target) =~ s/'/'"'"'/g;
		open my $p, "make -ndv 2>&1 '$esc' |"
			or die "could not run make: $!\n";
		while (<$p>) {
			next if not /^\Q$target\E:< = (.*)/;
			$deptarget{$_} = $target for split /\s/, $1;
			last;
		}

		close $p;
found:		close $f;
		exec('xpdf', '-remote', "wpdf-$target", $target) if fork == 0;
		next;
	} else {
		warn "skipping $_: not a pdf\n";
	}
}

# make pdf on demand
open my $p, '-|', 'watch', keys %deptarget
	or die "could not start watch: $!\n";
while (<$p>) {
	chomp;
	system('make', "$deptarget{$_}") == 0
		&& system('xpdf', '-remote', "wpdf-$deptarget{$_}", '-reload');
}
close $p;
exit($? != 0);