#!/usr/bin/perl
## ----------------------------------------------------------------------
## Debian GNU/Linux update-catalog version 0.2
## ----------------------------------------------------------------------
## Copyright (c) 2001-2004 Ardo van Rangelrooij
## Copyright (c) 2012 Helmut Grohne
## Copyright (c) 2012 Jakub Wilk
##
## This is free software; see the GNU General Public Licence version 2
## or later for copying conditions.  There is NO warranty.
## ----------------------------------------------------------------------

## ----------------------------------------------------------------------
use strict;

## ----------------------------------------------------------------------
$0 =~ m|[^/]+$|;

## ----------------------------------------------------------------------
use vars qw( $name );
$name = $&;

## ----------------------------------------------------------------------
use vars qw( $add );
use vars qw( $backup );
use vars qw( $catalog );
use vars qw( @data );
use vars qw( $debug );
use vars qw( $entry );
use vars qw( $quiet );
use vars qw( $remove );
use vars qw( $super );
use vars qw( $updatesuper );
use vars qw( $template );
use vars qw( $type );

## ----------------------------------------------------------------------
while ( $ARGV[0] =~ m/^--/ )
{
    $_ = shift( @ARGV );
    last if $_ eq '--';
    if ( $_ eq '--add' )
    {
        $add = 1;
    }
    elsif ( $_ eq '--remove' )
    {
        $remove = 1;
    }
    elsif ( $_ eq '--quiet' )
    {
        $quiet = 1;
    }
    elsif ( $_ eq '--super' )
    {
        $super = 1;
    }
    elsif ( $_ eq '--test' )
    {
        $debug = 1;
    }
    elsif ( $_ eq '--update-super' )
    {
        $updatesuper = 1;
    }
    elsif ( $_ eq '--help' )
    {
        &help;
	exit -1;
    }
    elsif ( $_ eq '--version' )
    {
        &help;
	exit -1;
    }
    else
    {
        print STDERR "$name: unknown option \`$_'\n";
	&help;
	exit 1;
    }
}

## ----------------------------------------------------------------------
if ( $add + $remove + $updatesuper != 1)
{
    print "Huh? You have to use precisely one out of --add --remove or --update-super.\n";
    exit 1;
}

## ----------------------------------------------------------------------
if ( $add || $remove )
{
    if ( ! @ARGV )
    {
        print STDERR "\n";
        &help;
        exit 1;
    }

    if ( $super )
    {
	$catalog = '/etc/sgml/catalog';
    }
    else
    {
	$catalog = shift( @ARGV );
    }

    if ( ! @ARGV )
    {
        print STDERR "\n";
        &help;
        exit 1;
    }

    $entry = shift( @ARGV );
}

## ----------------------------------------------------------------------
if ( @ARGV )
{
    print STDERR "$name: too many arguments\n";
    &help;
    exit 1;
}

## ----------------------------------------------------------------------
print STDERR "$name: test mode - catalog file will not be updated\n"
    if $debug && ! $quiet;

## ----------------------------------------------------------------------
if ( $super )
{
    print "update-catalog: Suppressing action on super catalog. Invoking trigger instead.\n";
    system("dpkg-trigger /etc/sgml");
    if ( $? != 0 )
    {
        print "Invocation of dpkg-trigger failed with status $?.\n";
        print "Forcing update of the super catalog...\n";
        &update_super;
    }
}
elsif ( $add )
{
    print "Adding entry $entry to catalog $catalog...\n"
        unless $quiet;
    
    &read_catalog_without_entry;
    &add_entry;
    &write_catalog;
}
elsif ( $remove )
{
    print "Removing entry $entry from catalog $catalog...\n"
        unless $quiet;
    
    &read_catalog_without_entry;
    &write_catalog;
}
elsif ( $updatesuper )
{
    print "Updating the super catalog...\n"
        unless $quiet;
    &update_super;
}

## ----------------------------------------------------------------------
exit 0;

## ----------------------------------------------------------------------
 sub read_catalog_without_entry
{
    if ( -f $catalog )
    {
	print "Reading catalog $catalog and removing entry $entry...\n"
	    if $debug;
	open( CATALOG, "<$catalog" )
	    or die "cannot open catalog $catalog for reading: $!";
	while ( <CATALOG> )
	{
	    chop;
	    push( @data, $_ ) unless m/$entry/;
	}
	close( CATALOG );
    }
    else
    {
	$type = $super ? 'super' : 'centralized';
	$template = "/usr/share/sgml-base/catalog.$type";
	print "Reading template $template...\n"
	    if $debug;
	open( TEMPLATE, "<$template" )
	    or die "cannot open template $template for reading: $!";
	while ( <TEMPLATE> )
	{
	    chop;
	    s|CATALOG|$catalog| if m/CATALOG/;
	    push( @data, $_ );
	}
	close( TEMPLATE );
    }
}

## ----------------------------------------------------------------------
sub add_entry
{
    print "Appending entry $entry...\n" if $debug;
    push( @data, "CATALOG $entry" );
}

## ----------------------------------------------------------------------
sub write_catalog
{
    $backup = $catalog . '.old';
    if ( not $debug )
    {
	if ( -f $catalog )
	{
	    # remove old backup file
	    if ( -f $backup )
	    {
		unlink( $backup )
		    or die "cannot remove backup copy $backup: $!";
	    }
	    rename( $catalog, $backup )
		or die "cannot rename $catalog to $backup: $!";
	}
	open( CATALOG, ">$catalog" )
	    or die "cannot open catalog $catalog for writing: $!";
	for ( @data ) { print CATALOG "$_\n"; };
	close( CATALOG );
    }
    else
    {
	print "Writing new entry to $catalog...\n";
	for ( @data ) { print "$_\n"; };
    }
}

## ----------------------------------------------------------------------
# Reference: https://www.oasis-open.org/specs/a401.htm
sub check_catalog($)
{
    my($catalog)=shift;
    my $base = $catalog;
    $base =~ s,/[^/]+$,,;
    my $catalog_tokens = qr{
        ( (?: \s+ | -- .*? --)+ # whitespace and comments
        | ' .*? ' | " .*? " # literal
        | \S+ # other tokens
        )
        }sx;
    unless(open(PKGCAT, "<", $catalog)) {
        print "Warning: Ignoring unreadable catalog file `$catalog'.\n"
            unless $quiet;
        return 0;
    };
    local $/;
    my $contents = <PKGCAT>;
    close PKGCAT;
    my $prevtoken = 0;
    while ($contents =~ m/$catalog_tokens/g) {
        my $token = $1;
        if ($prevtoken) {
            next if $token =~ m/^\s|^--/;
            $token =~ s/^(['"])(.*)\1$/$2/;
            if($prevtoken eq 'base') {
                $base = $token;
            } elsif($prevtoken eq 'catalog') {
                my $path;
                if($token =~ m,^/,) {
                    $path = $token;
                } else {
                    $path = "$base/$token";
                }
                if(not -f $path) {
                    print "Warning ignoring catalog `$catalog' which references non-existent catalogs. See man update-catalog for details.\n"
                        unless $quiet;
                    return 0;
                }
            }
            $prevtoken = 0;
        } elsif ("\L$token" eq 'catalog') {
            $prevtoken = 'catalog';
        } elsif ("\L$token" eq 'base') {
            $prevtoken = 'base';
        }
    }
    return 1;
}
## ----------------------------------------------------------------------
sub update_super
{
    my(@cats);
    my($catdir)="/etc/sgml";
    my($supercat)="/var/lib/sgml-base/supercatalog";
    my $catfile;
    opendir(CATDIR, $catdir)
        or die "cannot open catalog directory $catdir: $!";
    while( readdir CATDIR )
    {
        m/^[^.].*\.cat$/ or next;
        $catfile = $catdir . "/" . $_;
        check_catalog($catfile) or next;
        push(@cats, $catfile);
    }
    closedir(CATDIR)
        or die "cannot close catalog directory $catdir: $!";
    if ( not $debug )
    {
        open( CATALOG, ">$supercat.new")
            or die "cannot open $supercat.new for writing: $!";
        print CATALOG "--\n";
        print CATALOG "## This file is created by update-catalog with update-super.\n";
        print CATALOG "## Please see update-catalog(8) for how to modify this file.\n";
        print CATALOG "--\n";
        for ( @cats ) { print CATALOG "CATALOG $_\n"; }
        close( CATALOG );
        if( -e $supercat)
        {
            rename( $supercat, "$supercat.old" )
                or die "cannot rename $supercat to $supercat.old: $!";
        }
        rename( "$supercat.new", $supercat )
            or die "cannot rename $supercat.new to $supercat: $!";
   }
   else
   {
        print "The new super catalog would contain the following entries.\n";
        for ( @cats ) { print "CATALOG $_\n"; }
   }
}

## ----------------------------------------------------------------------
sub help
{
    print STDERR <<END;
Usage:
    $name <options> --add --super <centralized_catalog>
    $name <options> --add <centralized_catalog> <ordinary_catalog>
or
    $name <options> --remove --super <centralized_catalog>
    $name <options> --remove <centralized_catalog> <ordinary_catalog>

Options:
    --quiet         be quiet
    --test          do not modify any files, enables debugging mode
    --version       display version number
    --help          display this text
END
}

## ----------------------------------------------------------------------
sub version
{
    print "Debian $name version 0.2\n";
}

## ----------------------------------------------------------------------