#! /usr/bin/perl

use Getopt::Long; 
use IPC::Open2;
use warnings;
use strict;

Getopt::Long::Configure ("bundling");

# Give an array if the command has least one argument.
my @pdf2ps   = 'pdftops';
my @pscrop   = ('psnup2.pl', '-s1', '-l1');
my @psresize = 'psresize';
my @psnup    = 'psnup';
my @psbook   = 'psbook';
my @ps2pdf   = 'ps2pdf';

my $tmpdir   = '/tmp';


my $nup     = 1;
my $margin  = 1;
#TODO: units
my $crop;
my $book;
my $papersize;

GetOptions( "nup|n=i"       => \$nup,
            "1"             => sub { $nup = 1 },
            "2"             => sub { $nup = 2 },
            "4"             => sub { $nup = 4 },
            "8"             => sub { $nup = 8 },
            "crop|c"        => \$crop,
            "book|b"        => \$book,
            "papersize|p=s" => \$papersize,
            "margin|m=s"    => \$margin );

die "I can handle only one file at the same time :P"
    if $#ARGV > 0;

die "How should I put a non-positive number of pages per sheet?"
    if $nup <= 0;

unless (defined $papersize) {
    $papersize = `paperconf` or die "Can't guess papersize";
    chomp $papersize;
}

for (my $n = $nup; $n > 1; $n /= 2) {
    die "nup should be a power of two"
        unless $n % 2 == 0;
}

my $filename = $ARGV[0];
$filename = "-" unless defined $filename;
my $filename2 = $filename;
$filename2 = "(stdin)" if $filename eq "-";


my ($mresize, $mcrop, $mnup) = (0,0,0);

if (defined $crop) {
    $mresize = 0;
    if (not defined $book && $nup > 1) {
        $mcrop = $margin/2;
        $mnup  = $mcrop;
    } else {
        $mcrop = $margin;
        $mnup  = 0;
    }
} else {
    $mcrop = 0;
    if (not defined $book && $nup > 1) {
        $mresize = $margin/2;
        $mnup    = $mresize;
    } else {
        $mresize = $margin;
        $mnup    = 0;
    }
}




open(FILE, $filename)
    or die "Can't read `$filename'";

my $filetype;
my $fstline  = <FILE>;
if (defined $fstline && $fstline =~ /%!PS.*/) {
    $filetype = "PS";
} elsif (defined $fstline && $fstline =~ /%PDF.*/) {
    $filetype = "PDF";
} else {
    die "Can't recognize the type of `$filename2'";
}

# Auxiliary files, to remove
my @auxfiles;

# Auxiliary file descriptors, to close
my @auxfds;


# Pids, to waid for
my @pids;
my $pid;

if ($filename eq "-") {
    # Need to copy the whole input to an auxiliary file, since
    # conversion from pdf to ps requires random access to the data
    
    # TODO: only for pdfs
    $filename = "$tmpdir/pdftool-stdin-" . int(rand 2**16) . lc ".$filetype";
    open AUXFD, '>', "$filename"
        or die "Can't read write into `$filename'";
    push @auxfiles, "$filename";
    
    # cat > $filename
    seek STDIN, 0, 0;
    while (<FILE>) {
        print AUXFD $_;
    }
    close AUXFD;
}
close FILE;


# Convert to ps, or read the input file
if ($filetype eq "PDF") {
    $pid = open *INPS, "-|", @pdf2ps, "$filename", '-'
               or die "Error with `@pdf2ps $filename -'";
    push @pids, $pid;
} else {
    open *INPS, '<', "$filename"
        or die "Can't open `$filename'";
}
push @auxfds, fileno INPS;


# Resize file to our papersize
$pid = open2 *PSRESIZE, "<&INPS", @psresize, "-p$papersize"
           or die "Error with `@psresize -p$papersize'";
# Note: open2 closes the filehandles for us :)
push @pids, $pid;


# Pscrop
if (defined $crop) {
    $pid = open2 *PSCROP, "<&PSRESIZE", @pscrop, "-p$papersize", "-m${mnup}"
               or die "Error with `@pscrop -p$papersize -m${mnup}cm'";
    push @pids, $pid;
} else {
    *PSCROP = *PSRESIZE;
}

# Psbook
if (defined $book) {
    $pid = open2 *PSBOOK, "<&PSCROP", "@psbook"
               or die "Error with `@psbook";
    push @pids, $pid;
} else {
    *PSBOOK = *PSCROP;
}

# Psnup
# TODO: sometimes unecessary
$pid = open2 *PSNUP, "<&PSBOOK", @psnup, "-p$papersize", "-m${mnup}cm", "-$nup"
           or die "Error with `@psnup -p$papersize -m${mnup}cm -$nup'";
push @pids, $pid;

# Convert back to pdf
# TODO: not always stdout
# TODO: return same type as input
$pid = open2 ">&STDOUT", "<&PSNUP", @ps2pdf, "-sPAPERSIZE=$papersize", '-', '-'
           or die "Error with `@ps2pdf -sPAPERSIZE=$papersize - -'";
push @pids, $pid;


# Avoid zombies
map {waitpid $_, 0} @pids;


# Close auxiliary filehandles
map {close $_} @auxfds;


# Delete auxiliary files
unlink @auxfiles;