#!/usr/bin/perl

# Combine generated html page with GNU boilerplate.

# Copyright (C) 2012, 2020 Free Software Foundation, Inc.

# Copying and distribution of this file, with or without modification,
# are permitted in any medium without royalty provided the copyright
# notice and this notice are preserved.  This file is offered as-is,
# without any warranty.

# Written by Brendan O'Dea <bod@debian.org>

use strict;
use warnings;
use File::Temp;
use Getopt::Long;

my %opts;
die "Usage: $0 [--quiet] [--stdout]\n"
    unless GetOptions \%opts, qw(quiet stdout) and !@ARGV;

undef $/;

# Fetch GNU boilerplate
my $boilerplate;
my $url = 'http://www.gnu.org/server/standards/boilerplate-source.html';
do {
    open my $b, '-|', 'curl', '-sL', $url or die "curl: $!";
    $boilerplate = <$b>;
    ($url) = $boilerplate =~ /<meta\s+http-equiv=["']?refresh["']?\s+
	                      content=["']\d+;\s+url=["']?(http[^"'>]*)/xi;
} while $url;

for ($boilerplate)
{
    s#\$Revision:\s+(\S+)\s+\$#$1#;
    s#<!-- ~+ -->(?:\s+<!--.*?-->)*##s;
    s#<title>Baz\s+(- GNU Project)#<title>help2man $1#s;
    s#\bbug-baz\b#bug-help2man#g;
    s#<h2>GNU\sBaz</h2>.*(</div><!--\s+for\s+id="content")#%body%$1#s;
}

my ($header, $footer) = split /%body%/, $boilerplate;
die "can't parse boilerplate" unless $footer;

# Generate manual from texinfo
my $texi_tmp = File::Temp->new();
system 'makeinfo', '--html', '--no-number-sections', '--no-headers',
    '--no-split', '--output=' . $texi_tmp->filename, 'help2man.texi';

my $gnu_standards = "http://www.gnu.org/prep/standards/standards.html";
my $body = <$texi_tmp>;
for ($body)
{
    s#^.*<body(?:\s[^>]*)?>##s;
    s#</body>.*##s;

    # Fixup references
    s#<a\s+href="standards\.html#<a href="$gnu_standards#g;
    s#<a\s+href="\*manpages\*\.html\#perlre"
        #<a href="http://perldoc.perl.org/perlre.html"#xg;

    # Drop heading sizes by one, as h1 is quite loud.
    s#<(/?)h(\d)\b#"<${1}h" . ($2 + 1)#ge;
}

# Write output
my $target = $0;
my $tmp;
if ($opts{stdout})
{
    *OUT = *STDOUT;
    $opts{quiet} = 1;
}
else
{
    $target =~ s!.*/!!;
    $target =~ s/\.PL$// or die "$0: can't determine target name\n";
    $tmp = "$target.tmp$$";
    unlink $tmp          or die "$0: can't unlink $tmp ($!)\n" if -e $tmp;
    open OUT, ">$tmp"    or die "$0: can't create $tmp ($!)\n";
}

print "Extracting $target (with GNU boilerplate)\n"
    unless $opts{quiet};

print OUT $header, $body, $footer;

# Fix output file permissions
unless ($opts{stdout})
{
    close OUT;
    rename $tmp, $target or die "$0: can't rename $tmp to $target ($!)\n";
    chmod 0444, $target or warn "$0: can't change mode of $target ($!)\n";
}

exit 0;