#! /usr/bin/perl
#
# Copyright (c) 2004  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-include -- tiny file inclusion processoor for HTML.
#
# Usage:
#     html-include [-o output-file] [input-file]
#
# `html-include' extracts file inclusion directives in HTML, and output
# the result.  The following is file inclusion directive line that
# `html-include' recognizes:
# 
#      <!-- #include "file-name" -->
#
# Note that "<!--" must located at the beginning of the line.
#
# `html-include' outputs contents of "file-name" instead of the directive
# line itself.  If `file-name' also contains the file inclusion directive,
# `html-include' processes the line as well.
#
# If `input-file' is specified, `html-include' reads it.  Otherwise,
# it reads HTML from standard input.  `html-include' outputs the result
# to standard out by default, but you can specify output file by using
# `-o' option.
#
# Options:
#     -o output-file        output the result to the file.
#     -c                    add inclusion log lines to the result.
#     -I path               add file search path.
#

require 5.005;
use FileHandle;

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

#
# Variables
#
my @in_files = ();
my $out_file;
my @search_paths = ();

my $max_nest_level = 5;
my $comment_mode = 0;

$in_files[0] = {'handle' => new FileHandle,
		'name' => '-',
		'lineno' => 0};
$out_file =    {'handle' => new FileHandle,
		'name' => '-',
		'lineno' => 0};

#
# Parse command line arguments.
#
while (@ARGV > 0 && $ARGV[0] =~ /^-(.)(.*)/) {
    my ($first, $rest) = ($1, $2);
    if ($ARGV[0] eq '--') {
	shift;
	last;
    }

    if ($first eq 'o') {
	if ($rest ne '') {
	    $out_file->{name} = $rest;
	    shift;
	} elsif (@ARGV > 1) {
	    $out_file->{name} = $ARGV[1];
	    shift;
	    shift;
	} else {
	    die "$0: option requires an argument -- $first\n";
	}
    } elsif ($first eq 'c') {
	$comment_mode = 1;
	if ($rest ne '') {
	    $ARGV[0] = "-$rest";
	} else {
	    shift;
	}
    } elsif ($first eq 'I') {
	if ($rest ne '') {
	    push(@search_paths, $rest);
	    shift;
	} elsif (@ARGV > 1) {
	    push(@search_paths, $rest);
	    shift;
	    shift;
	} else {
	    die "$0: option requires an argument -- $first\n";
	}
    } else {
	die "$0: invalid option -- $first\n";
    }
}

die $usage if (@ARGV > 1);

#
# Open input and output files.
#
if (@ARGV == 0 || $ARGV[0] eq '-') {
    $in_files[0]->{name} = 'stdin';
    $in_files[0]->{handle}->open("<& STDIN");
} else {
    $in_files[0]->{name} = $ARGV[0];
    if (!$in_files[0]->{handle}->open('<' . $in_files[0]->{name})) {
	die "$0: failed to open the file, $!: " . $in_files[0]->{name} . "\n";
    }
}

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

#
# Read input files and write the result.
#
my $i = 0;

for (;;) {
    for (;;) {
	$_ = $in_files[$i]->{handle}->getline();
	last if (!defined($_));
	$in_files[$i]->{lineno}++;
	chomp;

	if (m|^<!--[ \t]+\#include[ \t]+\"([^\"]+)\"[ \t]+-->[ \t]*$|) {
	    #
	    # This is file inclusion directive line.
	    #
	    if (++$i >= $max_nest_level) {
		die "$0: too deep inclusion\n";
	    }

	    $in_files[$i] = {'handle' => new FileHandle,
			     'name' => search_file($1),
			     'lineno' => 0};
	    if (!$in_files[$i]->{handle}->open('<' . $in_files[$i]->{name})) {
		die "$0: failed to open the file, $!: " .
		    $in_files[$i]->{name} . "\n";
	    }

	    if ($comment_mode) {
		print $out_file->{handle}->printf("<!-- \"%s\" line %d -->\n",
						  $in_files[$i]->{name},
						  $in_files[$i]->{lineno} + 1);
	    }
	} else {
	    $out_file->{handle}->print($_, "\n");
	}

	$out_file->{lineno}++;
    }
    
    $in_files[$i]->{handle}->close();
    last if (--$i < 0);

    if ($comment_mode) {
	$out_file->{handle}->printf("<!-- \"%s\" line %d -->\n",
				    $in_files[$i]->{name},
				    $in_files[$i]->{lineno} + 1);
    }
}


sub search_file ($) {
    my ($file) = @_;

    foreach my $dir (@search_paths) {
	return "$dir/$file" if (-r "$dir/$file");
    }

    return $file;
}
