#!/usr/bin/perl -s

use Time::HiRes qw[tv_interval gettimeofday];
use Time::Piece;

our ($big, $from, $to, $prefix, $opaque, $h, $v);


sub progress($$$) {
    return if $v;
    printf STDERR "\r[%s%%|ETA %s] %- 50s" => @_
}
sub format_time($) { my $t = Time::Piece->strptime(int($_[0]),"%s"); $t->hms }

sub execute($) {
    my $cmd = shift;
    print "[$cmd]\n" if defined $v;
    system $cmd;
}

if ($h) {
    print "-big -v -from -to -prefix -opaque -h\n";
    exit 0;
}

my $filename = shift;

my $info = `pdfinfo $filename`;
my ($pages) = grep { /Pages:\s+\d+/ } split /\n/, $info;
$pages =~ /(\d+)/;
$pages = $1;

$from ||= 1;
$to   ||= $pages;

print STDERR "$filename has $pages pages.\n";

my $t0 = [gettimeofday];
my $eta = format_time(1_000_000);
my $nr_pages = $to - $from + 1;

print STDERR "Extracting $nr_pages (from $from to $to)\n";

print STDERR "...";
for my $i ($from..$to) {
    my $percent = sprintf "%6.2f" => (($i-$from)/$nr_pages)*100;

    progress $percent, $eta => "Extracting page $i from PDF";

    my $name = sprintf("%04d", $i);
    $name = $prefix.$name if defined($prefix);
    execute "pdftops -f $i -l $i $filename $name.ps";

    progress $percent, $eta => "Converting page $i to $name.png";

    $opaque = defined($opaque) ? '-background white -flatten' : '';

    if ($big) {
        execute "convert -density 600x600 $name.ps -density 600x600 $opaque $name.png";
    } else {
        execute "convert -density 300x300 $name.ps -density 300x300 $opaque $name.png";
    }
    progress $percent, $eta => "Removing temporary files.";

    unlink "$name.ps";

    if ($i % 2) {
        my $elapsed = tv_interval $t0;
        ## $i-$from+1 = $elapsed
        ## $to-$i     == $x
        $eta = format_time(($elapsed * ($to-$i))/($i-$from+1));
    }
}
progress 100, '00:00:00' => "DONE";

printf STDERR "\n";