#!/usr/local/bin/perl -w

# Generate a short man page from --help and --version output.
# Copyright © 1997, 98, 99 Free Software Foundation, Inc.

# 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, 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

# Written by Brendan O'Dea <bod@compusol.com.au>

use 5.004;
use strict;
use Getopt::Long;
use Text::Tabs qw(expand);
use POSIX qw(strftime setlocale LC_TIME);

my $this_program = 'help2man';
my $this_version = '1.013';
my $version_info = <<EOT;
$this_program $this_version

Copyright (C) 1997, 98, 99 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Written by Brendan O'Dea <bod\@compusol.com.au>
EOT

my $help_info = <<EOT;
`$this_program' generates a man page out of `--help' and `--version' output.

Usage: $this_program [OPTION]... EXECUTABLE

 -n, --name=STRING       use `STRING' as the description for the NAME paragraph
 -s, --section=SECTION   use `SECTION' as the section for the man page
 -i, --include=FILE      include material from `FILE'
 -I, --opt-include=FILE  include material from `FILE' if it exists
 -o, --output=FILE       send output to `FILE'
 -N, --no-info           suppress pointer to Texinfo manual
     --help              print this help, then exit
     --version           print $this_program program version number, then exit

EXECUTABLE should accept `--help' and `--version' options.
EOT

my $section = 1;
my ($include, $opt_name, $opt_include, $opt_output, $opt_no_info);

# Parse options.
Getopt::Long::config('bundling');
GetOptions (
    'n|name=s'		=> \$opt_name,
    's|section=s'	=> \$section,
    'i|include=s'	=> \$include,
    'I|opt-include=s'	=> \$opt_include,
    'o|output=s'	=> \$opt_output,
    'N|no-info'		=> \$opt_no_info,
    help		=> sub { print $help_info; exit },
    version		=> sub { print $version_info; exit },
) or die $help_info;

die $help_info unless @ARGV == 1;

my %include = ();
my @include = (); # to retain order

# Process include file (if given).  Format is:
#
# [section name]
# verbatim text

if ($include or $opt_include)
{
    if (open INC, $include || $opt_include)
    {
	my $sect;

	while (<INC>)
	{
	    if (/^\[([^]]+)\]/)
	    {
		$sect = uc $1;
		$sect =~ s/^\s+//;
		$sect =~ s/\s+$//;
		next;
	    }

	    # Silently ignore anything before the first
	    # section--allows for comments and revision info.
	    next unless $sect;

	    push @include, $sect unless $include{$sect};
	    $include{$sect} ||= '';
	    $include{$sect} .= $_;
	}

	close INC;

	die "$this_program: no valid information found in `$include'\n"
	    unless %include;

	# Compress trailing blank lines.
	for (keys %include)
	{
	    $include{$_} =~ s/\n+$//;
	    $include{$_} .= "\n" unless /^NAME$/;
	}
    }
    else
    {
	die "$this_program: can't open `$include' ($!)\n" if $include;
    }
}

# Turn off localisation of executable's ouput.
@ENV{qw(LANGUAGE LANG LC_ALL)} = ('C') x 3;

# Turn off localisation of date (for strftime)
setlocale LC_TIME, 'C';

# Expand tabs, strip trailing spaces and break into paragraphs
sub paragraphs { split /\n\n+/, join '', expand @_ }

# Grab help and version paragraphs from executable
my @help = paragraphs `$ARGV[0] --help 2>/dev/null`
    or die "$this_program: can't get `--help' info from $ARGV[0]\n";

my @version = paragraphs `$ARGV[0] --version 2>/dev/null`
    or die "$this_program: can't get `--version' info from $ARGV[0]\n";

my $date = strftime "%B %Y", localtime;
(my $program = $ARGV[0]) =~ s!.*/!!;
my $package = $program;
my $version;

if ($opt_output)
{
    unlink $opt_output
	or die "$this_program: can't unlink $opt_output ($!)\n"
	if -e $opt_output;

    open STDOUT, ">$opt_output"
	or die "$this_program: can't create $opt_output ($!)\n";
}

# The first line of the --version information is assumed to be in one
# of the following formats:
#
#   <version>
#   <program> <version>
#   {GNU,Free} <program> <version>
#   <program> ({GNU,Free} <package>) <version>
#   <program> - {GNU,Free} <package> <version>
#
# and seperated from any copyright/author details by a blank line.

$_ = shift @version;

if (/^(\S+) +\(((?:GNU|Free) +[^)]+)\) +(.*)/ or
    /^(\S+) +- *((?:GNU|Free) +\S+) +(.*)/)
{
    $program = $1;
    $package = $2;
    $version = $3;
}
elsif (/^((?:GNU|Free) +)?(\S+) +(.*)/)
{
    $program = $2;
    $package = $1 ? "$1$2" : $2;
    $version = $3;
}
else
{
    $version = $_;
}

$program =~ s!.*/!!;

# no info for `info' itself
$opt_no_info = 1 if $program eq 'info';

# --name overrides --include contents
$include{NAME} = "$program \\- $opt_name" if $opt_name;

# Default (useless) NAME paragraph
$include{NAME} ||= "$program \\- manual page for $program $version";

# Man pages traditionally have the page title in caps.
my $PROGRAM = uc $program;

# Header.
print <<EOT;
.\\" DO NOT MODIFY THIS FILE!  It was generated by $this_program $this_version.
.TH $PROGRAM "$section" "$date" "$package $version" FSF
.SH NAME
$include{NAME}
EOT

my $break;
my $accumulate = 1;
my @description = ();

sub convert_option;

# Output converted --help information.
for (@help)
{
    chomp;

    if (s/^Usage: +\S+ +(.*)\n?//)
    {
	# Turn the usage clause into a synopsis.
	my $synopsis = '';

	do {
	    my $syn = $1;
	    $syn =~ s/(([][]|\.\.+)+)/\\fR$1\\fI/g;
	    $syn =~ s/^/\\fI/ unless $syn =~ s/^\\fR//;
	    $syn .= '\fR';
	    $syn =~ s/\\fI( *)\\fR/$1/g;

	    $synopsis .= ".br\n" unless $accumulate;
	    $synopsis .= ".B $program\n";
	    $synopsis .= "$syn\n";
	    $accumulate = 0;
	} while s/^(?:Usage| *or): +\S+ +(.*)\n?//;

	# Include file overrides SYNOPSIS.
	print ".SH SYNOPSIS\n", $include{SYNOPSIS} || $synopsis;

	# Dump any accumulated description text.
	print ".SH DESCRIPTION\n";
	print @description;

	# Add additional description text from include file.
	if ($include{DESCRIPTION})
	{
	    print ".PP\n" unless $include{DESCRIPTION} =~ /^\..P/;
	    print $include{DESCRIPTION};
	}

	$break = 1;
	next unless $_;
    }

    # Accumulate text if the synopsis has not been produced yet.
    if ($accumulate)
    {
	push @description, ".PP\n" if @description;
	push @description, "$_\n";
	next;
    }

    # Convert some standard paragraph names
    if (s/^(Options|Examples): *\n//)
    {
	print qq(.SH \U$1\n);
	$break = '';
	next unless length;
    }

    # Catch bug report text.
    if (/^Report bugs |^Email bug reports to /)
    {
	print qq(.SH "REPORTING BUGS"\n$_\n);
	$break = '';
	next;
    }

    # Option subsections have second line indented.
    if (s/^(\S.*)\n / /)
    {
	print qq(.SS "$1"\n);
	$break = '';
    }

    my $output = '';
    while (length)
    {
	my $indent = 0;

	# Tagged paragraph
	if (s/^( +(\S.*?)  +)(\S.*)\n?//)
	{
	    $indent = length $1;
	    $output .= ".TP\n$2\n$3\n";
	    $break = 1;
	}

	# Indented paragraph
	elsif (s/^( +)(\S.*)\n?//)
	{
	    $indent = length $1;
	    $output .= ".IP\n$2\n";
	    $break = 1;
	}

	# Left justified paragraph
	else
	{
	    s/(.*)\n?//;
	    $output .= ".PP\n" if $break;
	    $output .= "$1\n";
	    $break = 1;
	}

	# Continuations
	$output .= "$1\n" while s/^ {$indent}(\S.*)\n?//;
    }

    $_ = $output;

    # Escape backslashes.
    s/\\/\\e/g;

    # Convert options.
    s/(^| )(-[][\w=-]+)/$1 . convert_option $2/mge;
    print;
}

# Print any include items other than the ones we have already dealt
# with.
for (@include)
{
    print qq(.SH "$_"\n$include{$_})
	unless /^(NAME|SYNOPSIS|DESCRIPTION|SEE ALSO)$/;
}

# Refer to the real documentation.
if ($include{'SEE ALSO'} or !$opt_no_info)
{
    print qq(.SH "SEE ALSO"\n);
    print $include{'SEE ALSO'}, ".PP\n" if $include{'SEE ALSO'};

    print <<EOT unless $opt_no_info;
The full documentation for
.B $program
is maintained as a Texinfo manual.  If the
.B info
and
.B $program
programs are properly installed at your site, the command
.IP
.B info $program
.PP
should give you access to the complete manual.
EOT
}

# Output converted --version information.
for (@version)
{
    chomp;

    # Join hyphenated lines.
    s/([A-Za-z])-\n */$1/g;

    # Convert copyright symbol or (c) to nroff character.
    s/Copyright +(?:\xa9|\([Cc]\))/Copyright \\(co/g;

    # Insert appropriate headings for copyright and author.
    if    (/^Copyright \\/) { print ".SH COPYRIGHT\n" }
    elsif (/^Written +by/)  { print ".SH AUTHOR\n" }
    else		    { print ".PP\n"; }

    # Insert line breaks before additional copyright messages and the
    # disclaimer.
    s/(.)\n(Copyright |This is free software)/$1\n.br\n$2/g;

    print "$_\n";
}

exit;

# Convert option dashes to \- to stop nroff from hyphenating 'em, and
# embolden.  Option arguments get italicised.
sub convert_option
{
    my $option = '\fB' . shift;

    $option =~ s/-/\\-/g;
    unless ($option =~ s/\[=(.*)\]$/\\fR[=\\fI$1\\fR]/)
    {
	$option =~ s/=(.)/\\fR=\\fI$1/;
	$option =~ s/ (.)/ \\fI$1/;
	$option .= '\fR';
    }

    $option;
}
