#!/usr/bin/env perl
# podwrapper.pl
# Copyright (C) 2010-2020 Red Hat Inc.
# @configure_input@
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

use warnings;
use strict;

use Pod::Usage;
use Getopt::Long;
use Pod::Man;
use Pod::Simple;
use Pod::Simple::Text;
use Pod::Simple::XHTML;
use File::Basename;

# https://www.redhat.com/archives/libguestfs/2013-May/thread.html#00088
eval { $Text::Wrap::huge = "overflow" };

=head1 NAME

podwrapper.pl - Generate libguestfs documentation from POD input files

=head1 SYNOPSIS

 man_MANS = virt-foo.1
 
 virt-foo.1 $(top_builddir)/website/virt-foo.1.html: stamp-virt-foo.pod
 
 stamp-virt-foo.pod: virt-foo.pod
         $(PODWRAPPER) \
           --section 1 \
           --man virt-foo.1 \
           --html $(top_builddir)/website/virt-foo.1.html \
           --license GPLv2+ \
           --warning general \
           $<
         touch $@

=head1 DESCRIPTION

podwrapper.pl is a Perl script that generates various output formats
from POD input files that libguestfs uses for most documentation.

You must specify one input file, and one or more output formats.  The
output options are I<--man>, I<--html> and I<--text> (see below).

In C<Makefile.am> files, use a variation of the boilerplate shown in
the L</SYNOPSIS> section above.

=head1 POD FORMAT

For general information about the POD format, see L<perlpod(1)>.

podwrapper.pl has a couple of extensions for including files:

=over 4

=item C<__INCLUDE:F<filename.pod>__>

Include another POD file at the current position (this does not work
recursively).

The filename is found by searching first the current directory,
then each I<--path> directory (if used).

=item C<__VERBATIM:F<filename.txt>__>

As above but the file is included as verbatim text, meaning it is
prefixed by one space before being passed to POD processing.

=back

=head1 OPTIONS

=over 4

=cut

my $help;

=item B<--help>

Display brief help.

=cut

my $html;

=item B<--html output.html>

Write a web page to C<output.html>.  If this option is not
given, then no web page output is produced.

=cut

my @inserts;

=item B<--insert filename:__PATTERN__>

In the input file, replace the literal text C<__PATTERN__> with the
replacement file C<filename>.  You can give this option multiple
times.

The contents of C<filename> are treated as POD.
Compare and contrast with I<--verbatim>.

Although it is conventional to use C<__...__> (double underscores) for
patterns, in fact you can use any string as the pattern.

=cut

my @licenses;

=item B<--license GPLv2+>

=item B<--license LGPLv2+>

=item B<--license examples>

Add the given license to the end of the man page.  This parameter
is required.  The parameter may be given multiple times (eg. for
mixed content).

=cut

my $man;

=item B<--man output.n>

Write a man page to C<output.n> (C<n> is the manual section number).
If this option is not given, then no man page output is produced.

=cut

my $name;

=item B<--name name>

Set the name of the man page.  If not set, defaults to the basename
of the input file.

=cut

my @paths;

=item B<--path DIR>

Set the path used for searching for included files (see L</POD FORMAT>
above).  The current directory is always searched first so you don’t
need to add that explicitly.  Multiple I<--path> parameters can be
given, they are searched in order.

=cut

my $section;

=item B<--section N>

Set the section of the man page (a number such as C<1> for
command line utilities or C<3> for C API documentation).  If
not set, defaults to C<1>.

=cut

my $strict_checks = 1;

=item B<--no-strict-checks>

Disable strict checks of the man page.  This is only used
when generating the translated man pages in the C<po-docs>
subdirectory.

=cut

my $text;

=item B<--text output.txt>

Write a text file to C<output.txt>.  If this option is not
given, then no text output is produced.

=cut

my @verbatims;

=item B<--verbatim filename:__PATTERN__>

In the input file, replace the literal text C<__PATTERN__> with the
replacement file C<filename>.  You can give this option multiple
times.

The contents of C<filename> are inserted as verbatim text, and
are I<not> interpreted as POD.
Compare and contrast with I<--insert>.

Although it is conventional to use C<__...__> (double underscores) for
patterns, in fact you can use any string as the pattern.

=cut

my $warning = "not-set";

=item B<--warning general>

=item B<--warning ro-option>

Add a standard warning section near the top of the manual page,
warning the user not to use the tool in write mode or concurrently.

There are two variations of the warning: The I<--warning ro-option>
variation should be used with tools such as L<guestfish(1)> which have
an I<--ro> option.  The I<--warning general> variation should be used
with other tools that open the disk image for writes, with no
read-only option.

=item B<--warning custom>

Use I<--warning custom> if there is already a warning section in the
manual page.

=item B<--warning safe>

Use I<--warning safe> for tools which are safe, ie. only open disk
images in read-only mode, or just don't need a warning section.

=back

=cut

# Clean up the program name.
my $progname = $0;
$progname =~ s{.*/}{};

# Parse options.
GetOptions ("help|?" => \$help,
            "html=s" => \$html,
            "license=s" => \@licenses,
            "insert=s" => \@inserts,
            "man=s" => \$man,
            "name=s" => \$name,
            "path=s" => \@paths,
            "section=s" => \$section,
            "strict-checks!" => \$strict_checks,
            "text=s" => \$text,
            "verbatim=s" => \@verbatims,
            "warning=s" => \$warning,
    ) or pod2usage (2);
pod2usage (1) if $help;

die "$progname: missing argument: podwrapper input.pod\n" unless @ARGV == 1;
my $input = $ARGV[0];

die "$progname: $input: missing argument: --license parameter is required\n"
    if $strict_checks && @licenses == 0;

# There should be at least one output.
die "$progname: $input: no output format specified.  Use --man and/or --html and/or --text.\n"
    unless defined $man || defined $html || defined $text;

# Default for $name and $section.
$name = basename ($input, ".pod") unless defined $name;
$section = 1 unless defined $section;

# Is it a user command line tool?
my $cli_tool = $section == 1 && $name !~ /^guestfs-/;

# Warning parameter is mandatory for user tools in section 1.
if ($strict_checks && $cli_tool) {
    die "$progname: $input: missing argument: --warning parameter is missing or invalid\n"
        unless $warning eq "general" || $warning eq "ro-option" ||
               $warning eq "custom" || $warning eq "safe";
}

# Note that these @...@ are substituted by ./configure.
my $abs_top_srcdir = "@abs_top_srcdir@";
my $abs_top_builddir = "@abs_top_builddir@";
my $package_name = "@PACKAGE_NAME@";
my $package_version = "@PACKAGE_VERSION@";

die "$progname: ./configure substitutions were not performed"
    unless $abs_top_srcdir && $abs_top_builddir &&
    $package_name && $package_version;

# Create a stable date (thanks Hilko Bengen).
my $date;
my $filename = "$abs_top_srcdir/ChangeLog";
if (-r $filename) {
    open FILE, $filename or die "$progname: $filename: $!";
    while (<FILE>) {
        if (/^Date:\s+...\s+(...)\s+(\d+)\s+..:..:..\s+(\d{4})\s+.*$/) {
            my $i = 0;
            my %month =
              map { $_ => ++$i }
                (qw< Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec >);
            $date = sprintf '%04d-%02d-%02d', $3, $month{$1}, $2;
            last;
        }
    }
    close FILE;
}
$filename = "$abs_top_srcdir/.git";
if (!$date && -d $filename) {
    local $ENV{GIT_DIR} = $filename;
    $_ = `git show -s --format=%ci`;
    $date = $1 if /^(\d+-\d+-\d+)\s/;
}
if (!$date) {
    my ($day, $month, $year) = (gmtime($ENV{SOURCE_DATE_EPOCH} || time))[3,4,5];
    $date = sprintf ("%04d-%02d-%02d", $year+1900, $month+1, $day);
}

# Create a release string.
my $release = "$package_name-$package_version";

#print "input=$input\n";
#print "name=$name\n";
#print "section=$section\n";
#print "date=$date\n";
#print "warning=$warning\n";

# Read the input.
my $content = read_whole_file ($input);

# Perform @inserts.
foreach (@inserts) {
    my @a = split /:/, $_, 2;
    die "$progname: $input: no colon in parameter of --insert\n" unless @a >= 2;
    my $replacement = read_whole_file ($a[0]);
    my $oldcontent = $content;
    $content =~ s/$a[1]/$replacement/ge;
    die "$progname: $input: could not find pattern '$a[1]' in input file\n"
        if $content eq $oldcontent;
}

# Perform INCLUDE directives.
$content =~ s{__INCLUDE:([-a-z0-9_]+\.pod)__}
             {read_whole_file ("$1", use_path => 1)}ge;

# Turn external links to this man page into simple cross-section links.
$content =~ s,\QL<$name($section)/\E,L</,g;

# Perform @verbatims.
foreach (@verbatims) {
    my @a = split /:/, $_, 2;
    die "$progname: $input: no colon in parameter of --verbatim\n" unless @a >= 2;
    my $replacement = read_verbatim_file ($a[0]);
    my $oldcontent = $content;
    $content =~ s/$a[1]/$replacement/ge;
    die "$progname: $input: could not find pattern '$a[1]' in input file\n"
        if $content eq $oldcontent;
}

# Perform VERBATIM directives.
$content =~ s{__VERBATIM:([-a-z0-9_]+\.txt)__}
             {read_verbatim_file ("$1", use_path => 1)}ge;

# There should be no =encoding line present in the content (we will add one).
die "$progname: $input: =encoding must not be present in input\n"
    if $content =~ /^=encoding/m;

$content =~ s/^=(.*)/\n=encoding utf8\n\n=$1/m;

if ($strict_checks) {
    # Verify sections present / not present.
    die "$progname: $input: missing DESCRIPTION section\n"
        if $cli_tool && $content !~ /^=head1 DESCRIPTION/m;
    die "$progname: $input: missing AUTHOR or AUTHORS section\n"
        unless $content =~ /^=head1 AUTHOR/m;
    die "$progname: $input: missing SEE ALSO section\n"
        unless $content =~ /^=head1 SEE ALSO/m;
    die "$progname: $input: missing COPYRIGHT section\n"
        unless $content =~ /^=head1 COPYRIGHT/m;
    die "$progname: $input: BUGS is now added automatically, do not add it to the POD file\n"
        if $content =~ /^=head1 (REPORTING )?BUGS/m;
    die "$progname: $input: LICENSE is now added automatically, do not add it to the POD file\n"
        if $content =~ /^=head1 LICENSE/m;
    die "$progname: $input: GPL/LGPL should be specified using the --license parameter, not included in the POD file\n"
        if $content =~ /^This program is free software/ ||
        $content =~ /^This library is free software/;
    if ($warning eq "general" || $warning eq "ro-option" ||
        $warning eq "safe") {
        die "$progname: $input: WARNING is now added automatically using the --warning parameter\n"
            if $content =~ /^=head1 WARNING/m
    }
    elsif ($warning eq "custom") {
        die "$progname: $input: missing WARNING section\n"
            unless $content =~ /^=head1 WARNING/m;
    }
}

# Add standard LICENSE, BUGS and WARNING sections.
my $LGPLv2plus =
"This library is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
";

my $GPLv2plus =
"This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
";

my $examples_license =
"This manual page contains examples which we hope you will use in
your programs.  The examples may be freely copied, modified and
distributed for any purpose without any restrictions.
";

my $reporting_bugs =
"=head1 BUGS

To get a list of bugs against libguestfs, use this link:
L<https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools>

To report a new bug against libguestfs, use this link:
L<https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools>

When reporting a bug, please supply:

\=over 4

\=item *

The version of libguestfs.

\=item *

Where you got libguestfs (eg. which Linux distro, compiled from source, etc)

\=item *

Describe the bug accurately and give a way to reproduce it.

\=item *

Run L<libguestfs-test-tool(1)> and paste the B<complete, unedited>
output into the bug report.

\=back
";

my $warning_general =
"Using C<$name>
on live virtual machines, or concurrently with other
disk editing tools, can be dangerous, potentially causing disk
corruption.  The virtual machine must be shut down before you use this
command, and disk images must not be edited concurrently.";

my $warning_ro_option =
"Using C<$name> in write mode
on live virtual machines, or concurrently with other
disk editing tools, can be dangerous, potentially causing disk
corruption.  The virtual machine must be shut down before you use this
command, and disk images must not be edited concurrently.

Use the I<--ro> (read-only) option to use C<$name> safely if the disk
image or virtual machine might be live.  You may see strange or
inconsistent results if running concurrently with other changes, but
with this option you won't risk disk corruption.";

$content .= "\n\n=head1 LICENSE\n\n";

foreach (@licenses) {
    if ($_ eq "LGPLv2+") {
        $content .= $LGPLv2plus . "\n\n";
    }
    elsif ($_ eq "GPLv2+") {
        $content .= $GPLv2plus . "\n\n";
    }
    elsif ($_ eq "examples") {
        $content .= $examples_license . "\n\n";
    }
    else {
        die "$progname: $input: invalid --license parameter: $_\n";
    }
}

$content .= "\n\n$reporting_bugs";

if ($warning eq "general") {
    $content =~ s/^=head1 DESCRIPTION/=head1 WARNING\n\n$warning_general\n\n=head1 DESCRIPTION/m or die;
}
elsif ($warning eq "ro-option") {
    $content =~ s/^=head1 DESCRIPTION/=head1 WARNING\n\n$warning_ro_option\n\n=head1 DESCRIPTION/m or die;
}
# else do nothing for $warning "custom", "safe" or "not-set"

# Output man page.
SUBMAN: {
    package Podwrapper::Man;

    use vars qw(@ISA $VERSION);
    @ISA = qw(Pod::Man);
    $VERSION = $package_version;

    # Override the L<> method.
    sub cmd_l
    {
        my ($self, $attrs, $text) = @_;
        return $text;
    }
}

if ($man) {
    my $parser = Podwrapper::Man->new (
        name => $name,
        release => $release, section => $section,
        center => "Virtualization Support",
        date => $date,
        stderr => 1, utf8 => 1
    );
    my $output;
    $parser->no_errata_section (1);
    $parser->complain_stderr (1);
    $parser->output_string (\$output);
    $parser->parse_string_document ($content)
        or die "$progname: could not parse input document";
    open OUT, ">$man" or die "$progname: $man: $!";
    print OUT $output or die "$progname: $man: $!";
    close OUT or die "$progname: $man: $!";
    if ($parser->any_errata_seen) {
        unlink $man;
        die "$input: errors or warnings in this POD file, see messages above\n"
    }
    #print "$progname: wrote $man\n";
}

# Output HTML.
SUBHTML: {
    # Subclass Pod::Simple::XHTML.  See the documentation.
    package Podwrapper::XHTML;

    use vars qw(@ISA $VERSION);
    @ISA = qw(Pod::Simple::XHTML);
    $VERSION = $package_version;

    # Pod::Simple::XHTML returns uppercase identifiers, whereas the
    # old pod2html returns lowercase ones.
    sub idify
    {
        my $self = shift;
        my $id = $self->SUPER::idify (@_);
        lc ($id);
    }

    # Note this also allows links to related projects because they all
    # appear together under the http://libguestfs.org website.
    sub is_a_local_page
    {
        local $_ = shift;

        return 1 if /^Sys::Guestfs/;
        return 0 if /^virt-install/;
        return 1 if /^virt-/;
        return 1 if /^libguestf/;
        return 1 if /^guestf/;
        return 1 if /^guestmount/;
        return 1 if /^guestunmount/;
        return 1 if /^hivex/;
        return 1 if /^supermin/;
        return 1 if /^libnbd/;
        return 1 if /^nbd/;
        return 0;
    }

    sub resolve_pod_page_link
    {
        my $self = shift;
        my $podname = $_[0]; # eg. "Sys::Guestfs", can be undef
        my $anchor = $_[1];  # eg. "SYNOPSIS", can be undef
        my $r = "";
        if (defined $podname) {
            return $self->SUPER::resolve_pod_page_link (@_)
                unless is_a_local_page ($podname);
            $r .= "$podname.3.html"
        }
        $r .= "#" . $self->idify ($anchor, 1) if defined $anchor;
        $r;
    }

    sub resolve_man_page_link
    {
        my $self = shift;
        my $name = $_[0];   # eg. "virt-make-fs(1)", can be undef
        my $anchor = $_[1]; # eg. "SYNOPSIS", can be undef
        my $r = "";
        if (defined $name) {
            return $self->SUPER::resolve_man_page_link (@_)
                unless is_a_local_page ($name);
            $name =~ s/\((.*)\)$/.$1/;
            $r .= "$name.html";
        }
        $r .= "#" . $self->idify ($anchor, 1) if defined $anchor;
        $r;
    }

    # For some reason Pod::Simple::XHTML usually cannot find a
    # title for the page.  This defaults the HTML <title> field
    # to the same as the man page name.
    sub default_title { $name }
}

if ($html) {
    mkdir "$abs_top_builddir/website";

    my $parser = Podwrapper::XHTML->new;
    my $output;
    $parser->no_errata_section (1);
    $parser->complain_stderr (1);
    $parser->output_string (\$output);
    # Added in Pod::Simple 3.16, 2011-03-14.
    eval { $parser->html_charset ("UTF-8") };
    $parser->html_css ("pod.css");
    $parser->index (1);
    $parser->parse_string_document ($content);

    # Hack for Perl 5.16.
    $output =~ s{/>pod.css<}{/>\n<};

    open OUT, ">$html" or die "$progname: $html: $!";
    print OUT $output or die "$progname: $html: $!";
    close OUT or die "$progname: $html: $!";
    if ($parser->any_errata_seen) {
        unlink $html;
        die "$input: errors or warnings in this POD file, see messages above\n"
    }
    #print "$progname: wrote $html\n";
}

# Output text.
if ($text) {
    my $parser = Pod::Simple::Text->new;
    my $output;
    $parser->no_errata_section (1);
    $parser->complain_stderr (1);
    $parser->output_string (\$output);
    $parser->parse_string_document ($content);
    open OUT, ">$text" or die "$progname: $text: $!";
    binmode OUT, ":utf8";
    print OUT $output or die "$progname: $text: $!";
    close OUT or die "$progname: $text: $!";
    if ($parser->any_errata_seen) {
        unlink $text;
        die "$input: errors or warnings in this POD file, see messages above\n"
    }
    #print "$progname: wrote $text\n";
}

sub find_file
{
    my $input = shift;
    my $use_path = shift;
    local $_;

    my @search_path = (".");
    push (@search_path, @paths) if $use_path;
    foreach (@search_path) {
        return "$_/$input" if -f "$_/$input";
    }
    die "$progname: $input: cannot find input file on path"
}

sub read_whole_file
{
    my $input = shift;
    my %options = @_;
    local $/ = undef;

    $input = find_file ($input, $options{use_path});
    open FILE, $input or die "$progname: $input: $!";
    $_ = <FILE>;
    close FILE;
    $_;
}

sub read_verbatim_file
{
    my $input = shift;
    my %options = @_;
    my $r = "";

    $input = find_file ($input, $options{use_path});
    open FILE, $input or die "$progname: $input: $!";
    while (<FILE>) {
        $r .= " $_";
    }
    close FILE;
    $r;
}

=head1 SEE ALSO

L<perlpod(1)>,
L<Pod::Simple(3pm)>,
libguestfs.git/README.

=head1 AUTHOR

Richard W.M. Jones.

=head1 COPYRIGHT

Copyright (C) 2012-2020 Red Hat Inc.