#!/usr/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>
# Available from ftp://ftp.gnu.org/gnu/help2man/

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 = '1.020';
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 version number, then exit

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

my $section = 1;
my ($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'	=> sub { push @opt_include, [ pop, 1 ] },
    'I|opt-include=s'	=> sub { push @opt_include, [ pop, 0 ] },
    '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 %append = ();
my @include = (); # retain order given in include file

# Provide replacement `quote-regex' operator for pre-5.005.
BEGIN { eval q(sub qr { '' =~ $_[0]; $_[0] }) if $] < 5.005 }

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

for (@opt_include)
{
    my ($inc, $required) = @$_;

    next unless -f $inc or $required;
    die "$this_program: can't open `$inc' ($!)\n"
	unless open INC, $inc;

    my $key;
    my $hash = \%include;

    while (<INC>)
    {
	# [section]
	if (/^\[([^]]+)\]/)
	{
	    $key = uc $1;
	    $key =~ s/^\s+//;
	    $key =~ s/\s+$//;
	    $hash = \%include;
	    push @include, $key unless $include{$key};
	    next;
	}

	# /pattern/
	if (m!^/(.*)/([ims]*)!)
	{
	    my $pat = $2 ? "(?$2)$1" : $1;

	    # Check pattern.
	    eval { $key = qr($pat) };
	    if ($@)
	    {
		$@ =~ s/ at .*? line \d.*//;
		die "$inc:$.:$@";
	    }

	    $hash = \%append;
	    next;
	}

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

	$hash->{$key} ||= '';
	$hash->{$key} .= $_;
    }

    close INC;

    die "$this_program: no valid information found in `$inc'\n"
	unless $key;
}

# Compress trailing blank lines.
for my $hash (\(%include, %append))
{
    for (keys %$hash) { $hash->{$_} =~ s/\n+$/\n/ }
}

# 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';

# Grab help and version info from executable.
my ($help_text, $version_text) = map {
    join '', map { s/ +$//; expand $_ } `$ARGV[0] --$_ 2>/dev/null`
	or die "$this_program: can't get `--$_' info from $ARGV[0]\n"
} qw(help version);

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.

($_, $version_text) = split /\n+/, $version_text, 2;

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\n" if $opt_name;

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

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

# Extract usage clause(s) [if any] for SYNOPSIS.
if ($help_text =~ s/^Usage:( +(\S+))(.*)((?:\n(?: {6}\1| *or: +\S).*)*)//m)
{
    my @syn = $2 . $3;

    if ($_ = $4)
    {
	s/^\n//;
	for (split /\n/) { s/^ *(or: +)?//; push @syn, $_ }
    }

    my $synopsis = '';
    for (@syn)
    {
	$synopsis .= ".br\n" if $synopsis;
	s!^\S*/!!;
	s/^(\S+) *//;
	$synopsis .= ".B $1\n";
	s/\s+$//;
	s/(([][]|\.\.+)+)/\\fR$1\\fI/g;
	s/^/\\fI/ unless s/^\\fR//;
	$_ .= '\fR';
	s/(\\fI)( *)/$2$1/g;
	s/\\fI\\fR//g;
	s/^\\fR//;
	s/\\fI$//;
	s/^\./\\&./;

	$synopsis .= "$_\n";
    }

    $include{SYNOPSIS} ||= $synopsis;
}

# Process text, initial section is DESCRIPTION.
my $sect = 'DESCRIPTION';
$_ = "$help_text\n\n$version_text";

# Normalise paragraph breaks.
s/^\n+//;
s/\n*$/\n/;
s/\n\n+/\n\n/g;

# Temporarily exchange leading dots and backslashes for tokens.
s/^\./\x80/mg;
s/\\/\x81/g;

# Start a new paragraph (if required) for these.
s/([^\n])\n(Report +bugs|Email +bug +reports +to|Written +by)/$1\n\n$2/g;

sub convert_option;

while (length)
{
    # Convert some standard paragraph names.
    if (s/^(Options|Examples): *\n//)
    {
	$sect = uc $1;
	next;
    }

    # Copyright section
    if (/^Copyright +[(\xa9]/)
    {
	$sect = 'COPYRIGHT';
	$include{$sect} ||= '';
	$include{$sect} .= ".PP\n" if $include{$sect};

	my $copy;
	($copy, $_) = split /\n\n/, $_, 2;

	for ($copy)
	{
	    # Add back newline
	    s/\n*$/\n/;

	    # Convert iso9959-1 copyright symbol or (c) to nroff
	    # character.
	    s/^Copyright +(?:\xa9|\([Cc]\))/Copyright \\(co/mg;

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

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

	$include{$sect} .= $copy;
	$_ ||= '';
	next;
    }

    # Catch bug report text.
    if (/^(Report +bugs|Email +bug +reports +to) /)
    {
	$sect = 'REPORTING BUGS';
    }

    # Author section.
    elsif (/^Written +by/)
    {
	$sect = 'AUTHOR';
    }

    # Examples, indicated by an indented leading $, % or > are
    # rendered in a constant width font.
    if (/^( +)([\$\%>] )\S/)
    {
	my $indent = $1;
	my $prefix = $2;
	my $break = '.IP';
	$include{$sect} ||= '';
	while (s/^$indent\Q$prefix\E(\S.*)\n*//)
	{
	    $include{$sect} .= "$break\n\\f(CW$prefix$1\\fR\n";
	    $break = '.br';
	}

	next;
    }

    my $matched = '';
    $include{$sect} ||= '';

    # Sub-sections have a trailing colon and the second line indented.
    if (s/^(\S.*:) *\n / /)
    {
	$matched .= $& if %append;
	$include{$sect} .= qq(.SS "$1"\n);
    }

    my $indent = 0;
    my $content = '';

    # Option with description.
    if (s/^( {1,10}([+-]\S.*?))(?:(  +)|\n( {20,}))(\S.*)\n//)
    {
	$matched .= $& if %append;
	$indent = length ($4 || "$1$3");
	$content = ".TP\n\x82$2\n\x82$5\n";
	unless ($4)
	{
	    # Indent may be different on second line.
	    $indent = length $& if /^ {20,}/;
	}
    }

    # Option without description.
    elsif (s/^ {1,10}([+-]\S.*)\n//)
    {
	$matched .= $& if %append;
	$content = ".HP\n\x82$1\n";
	$indent = 80; # not continued
    }

    # Indented paragraph with tag.
    elsif (s/^( +(\S.*?)  +)(\S.*)\n//)
    {
	$matched .= $& if %append;
	$indent = length $1;
	$content = ".TP\n\x82$2\n\x82$3\n";
    }

    # Indented paragraph.
    elsif (s/^( +)(\S.*)\n//)
    {
	$matched .= $& if %append;
	$indent = length $1;
	$content = ".IP\n\x82$2\n";
    }

    # Left justified paragraph.
    else
    {
	s/(.*)\n//;
	$matched .= $& if %append;
	$content = ".PP\n" if $include{$sect};
	$content .= "$1\n";
    }

    # Append continuations.
    while (s/^ {$indent}(\S.*)\n//)
    {
	$matched .= $& if %append;
	$content .= "\x82$1\n"
    }

    # Move to next paragraph.
    s/^\n+//;

    for ($content)
    {
	# Leading dot protection.
	s/\x82\./\x80/g;
	s/\x82//g;

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

    # Check if matched paragraph contains /pat/.
    if (%append)
    {
	for my $pat (keys %append)
	{
	    if ($matched =~ $pat)
	    {
		$content .= ".PP\n" unless $append{$pat} =~ /^\./;
		$content .= $append{$pat};
	    }
	}
    }

    $include{$sect} .= $content;
}

# Refer to the real documentation.
unless ($opt_no_info)
{
    $sect = 'SEE ALSO';
    $include{$sect} ||= '';
    $include{$sect} .= ".PP\n" if $include{$sect};
    $include{$sect} .= <<EOT;
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 header.
print <<EOT;
.\\" DO NOT MODIFY THIS FILE!  It was generated by $this_program $this_version.
.TH $PROGRAM "$section" "$date" "$package $version" FSF
EOT

# Section ordering.
my @pre = qw(NAME SYNOPSIS DESCRIPTION OPTIONS EXAMPLES);
my @post = ('AUTHOR', 'REPORTING BUGS', 'COPYRIGHT', 'SEE ALSO');
my $filter = join '|', @pre, @post;

# Output content.
for (@pre, (grep ! /^($filter)$/o, @include), @post)
{
    if ($include{$_})
    {
	my $quote = /\W/ ? '"' : '';
	print ".SH $quote$_$quote\n";
	
	for ($include{$_})
	{
	    # Replace leading dot an backslash tokens.
	    s/\x80/\\&./g;
	    s/\x81/\\e/g;
	    print;
	}
    }
}

exit;

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

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

    $_;
}
