#! /usr/bin/perl
#
# Copyright (c) 2005-2006  Motoyuki Kasahara
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. Neither the name of the project nor the names of its contributors
#    may be used to endorse or promote products derived from this software
#    without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#

#
# html-toc -- make `table of contents' of HTML files.
#
# Usage:
#     html-index [option...] input-file...
#
# `html-toc' reads HTML files, and generates `table of contents' (TOC)
# of the HTML files. The TOC is created from <h1>...<h6> tags and
# <a name="..."> tag in the HTML files.  Since `html-toc' doesn't parse
# HTML precisely, the tags must be the following form:
# 
#      <h?><a name="...">heading</a></h?>
#
# where `?' is 1..6.  Note that <h?> and </h?> above must be in the same
# line.
#
# `html-toc' outputs TOC to standard out by default.
#
# Options:
#     -o file               specify output file.
#     -h                    do not output file name in <a href="....">.
#     -m level              minimum target heading level
#                           (default: h1)
#     -M level              maximum target heading level
#                           (default: h6)

require 5.005;
use Getopt::Std;

#
# Usage
#
my $usage = "Usage: $0 [option...] input-file...\n";

#
# Variables
#
my $out_file = '-';
my @preamble = ();
my $fragment_only = 0;
my $min_level = 1;
my $max_level = 6;

#
# Parse command line arguments.
#
my %options;
getopts('o:hm:M:', \%options) or die $usage;
die $usage if (@ARGV == 0);

$fragment_only = 1 if (defined($options{h}) || @ARGV == 1);
$out_file = $options{o} if (defined($options{o}));
if (defined($options{m})) {
    $options{m} =~ s/^h//;
    $min_level = $options{m};
}
if (defined($options{M})) {
    $options{M} =~ s/^h//;
    $max_level = $options{M};
}

#
# Read an HTML file.
#
$current_level = $min_level;

if ($out_file eq '-') {
    $out_file = 'stdout'; 
    open(OUT_FILE, ">& STDOUT");
} else {
    if (!open(OUT_FILE, "> $out_file")) {
	die "$0: failed to open the file, $!: $out_file\n";
    }
}

print OUT_FILE "<ul>\n";

foreach my $in_file (@ARGV) {
    if (!open(IN_FILE, "< $in_file")) {
	die "$0: failed to open the file, $!: $in_file\n";
    }

    while (<IN_FILE>) {
	chomp;
	next unless (m|^<h([1-6])><a name="([^\"]+)">(.*)</a>|);
	my ($level, $tag, $heading) = ($1, $2, $3);

	if ($level >= $min_level && $level <= $max_level) {
	    while ($current_level > $level) {
		$current_level--;
		print OUT_FILE ' ' x ($current_level - $min_level + 1);
		print OUT_FILE "</ul>\n";
	    }
	    while ($current_level < $level) {
		print OUT_FILE ' ' x ($current_level - $min_level + 1);
		print OUT_FILE "<ul>\n";
		$current_level++;
	    }

	    print OUT_FILE ' ' x ($current_level - $min_level + 1);
	    if ($fragment_only) {
		print OUT_FILE sprintf("<li><a href=\"\#%s\">%s</a>\n",
				       $tag, $heading);
	    } else {
		print OUT_FILE sprintf("<li><a href=\"%s\#%s\">%s</a>\n",
				       $in_file, $tag, $heading);
	    }
	}
    }

    close(IN_FILE);
}

while ($current_level > $min_level) {
    $current_level--;
    print OUT_FILE ' ' x ($current_level - $min_level + 1);
    print OUT_FILE "</ul>\n";
}

print OUT_FILE "</ul>\n";

close(OUT_FILE);