#!/usr/bin/perl -- # -*- Perl -*-

$dtd = shift @ARGV || die;

select(STDERR); $| = 1;
select(STDOUT); $| = 1;

%entity = ();
%used = ();

$pass = 1;
@dirstack = ('.');
&read_dtd($dtd);

$changed = 1;
while ($changed) {
    $changed = 0;
    foreach $ent (keys %entity) {
	&check_used("ENTITY $ent", $entity{$ent}) if $used{$ent};
    }
}

# Force local.* entities to be used for all entities that are used.
foreach $ent (keys %entity) {
    next if $ent !~ /^local\.(.*)$/;
    next if !$used{$1};
    $used{$ent} = 1;
}

print "<!-- *********************************************************************
     *** THIS IS THE FLATTENED DTD. DO NOT EDIT THIS DTD BY HAND, EDIT ***
     *** THE CUSTOMIZATION LAYER AND REGENERATE THE FLATTENED DTD! ********
     ********************************************************************* -->\n\n";

open (F, $dtd);
while (<F>) {
    last if /^<!A/ || /^<!N/ || /^<!E/;
    print $_;
}
close (F);
print "\n";

$pass = 2;
%entity = ();
@dirstack = ('.');
&read_dtd($dtd);

sub read_dtd {
    my($dtd) = shift;
    my($totsize);
    local(*F, $_);

    # HACK HACK HACK
    if ($dtd =~ /http:\/\/www.oasis-open.org\/docbook\/xml\/simple\/.*\/([^\/]+)$/
	|| $dtd =~ /http:\/\/docbook.org\/xml\/simple\/.*\/([^\/]+)$/) {
	print STDERR "$dtd ==>\n";
	$dtd = "/sourceforge/docbook/docbook/simple/$1";
	print STDERR "\t$dtd\n";
    }

    # HACK HACK HACK
    if ($dtd =~ /http:\/\/www.oasis-open.org\/docbook\/xml\/(.*)$/
	|| $dtd =~ /http:\/\/docbook.org\/xml\/(.*)$/) {
	print STDERR "$dtd ==>\n";
	$dtd = "/share/websites/docbook/xml/$1";
	print STDERR "\t$dtd\n";
    }

    # HACK HACK HACK
    if ($dtd =~ /http:\/\/www.w3.org\/2003\/entities\/(.*)$/) {
	print STDERR "$dtd ==>\n";
	$dtd = "/projects/w3c/WWW/2003/entities/$1";
	print STDERR "\t$dtd\n";
    }

    if (! -f $dtd) {
	$dtd = $dirstack[$#dirstack] . "/" . $dtd;
    }

    if ($dtd =~ /^(.*)[\/\\]([^\/\\]+)$/) {
	push (@dirstack, $1);
    } else {
	push (@dirstack, ".");
    }

    open (F, $dtd) || die "Cannot open $dtd\n";
    read (F, $_, -s $dtd);
    close (F);

    print STDERR "\nParsing $dtd...\n";
    $totsize = -s $dtd;

    while (/^.*?<!(.*?)>/s) {
	my($decl) = $1;
	my($rest) = $';

	# comments are a special case...
	if ($decl =~ /^--/) {
	    /^.*?<!(--.*?--)>/s;
	    $decl = $1;
	    $rest = $';
	}

	# marked sections are a special case...
	if ($decl =~ /^\[\s*%(.*?);?\s*\[/s) {
	    my($mspe) = $1;
	    my($depth) = 1;
	    my($content) = "";
	    $_ = $' . ">" . $rest;
#	    print STDERR "$mspe:\n";
#	    print STDERR "!!>", substr($_, 0, 200), "<!!\n";
	    while (($depth > 0) && /^(.*?)((<!\[)|(\]\]>))/s) {
		$content .= $1;
		if ($4) {
		    $depth--;
		    if ($depth > 0) {
			$content .= $4;
		    }
		} else { 
		    $depth++;
		    $content .= $3;
		}
		$_ = $';
	    }
#	    print STDERR "**>$content<**\n";

	    $rest = $_;

	    if ($entity{$mspe} eq 'INCLUDE') {
#		print STDERR "\nIncluding $mspe...\n";
		$_ = $content . $rest;
		next;
	    } elsif ($entity{$mspe} eq 'IGNORE') {
#		print STDERR "\nSkipping $mspe...\n";
		$_ = $rest;
		next;
	    } else {
		die "Invalid MSPE: $mspe ", $entity{$mspe}, "\n";
	    }
	}

	$_ = $rest;

#	print STDERR "\n$decl\n";

	$percent = (($totsize - length($rest)) / $totsize) * 100;
	printf STDERR "%05.1f\r", $percent;

	if ($pass > 1) {
	    &output($decl);
	} else {
	    &handle($decl);
	}
    }

    pop (@dirstack);
}

sub handle {
    my($decl) = shift;

    if ($decl =~ /^ENTITY % (\S+)\s+(PUBLIC\s+\".*?\"|SYSTEM)\s+\"(.*?)\"/s) {
	my($ent) = $1;
	my($pub) = $2;
	my($sys) = $3;
	if (0 && $pub =~ /^PUBLIC\s+\"ISO/s) {
	    # charent
	} else {
	    if (!exists($entity{$ent})) {
#		print STDERR "Reading $sys\n";
		&read_dtd($sys);
	    }

	    $entity{$ent} = "%%%";
	}
    } elsif ($decl =~ /^ENTITY % (\S+)\s+([\'\"])(.*?)\2/s) {
	my($ent, $val) = ($1, $3);

	if (!exists($entity{$ent})) {
	    $entity{$ent} = $val;

#	    if ($ent =~ /^local\./) {
#		print STDERR "\nForcing $ent to be used.\n";
#		$used{$ent} = 1;
#	    }
	}
    } elsif ($decl =~ /^ENTITY\s+(\S+)\s+([\'\"])(.*?)\2/s) {
	my($ent, $val) = ($1, $3);
	if (!exists($entity{$ent})) {
	    $entity{$ent} = $val;
	    $used{$ent} = 1;
	}
    } elsif ($decl =~ /^--.*?--/s) {
	# comment;
    } elsif ($decl =~ /^NOTATION\s+(\S+)/s) {
	# notation;
	&check_used("NOTATION $1", $decl);
    } elsif ($decl =~ /^ELEMENT\s+(\S+)/s) {
	# element
	&check_used("ELEMENT $1", $decl);
    } elsif ($decl =~ /^ATTLIST\s+(\S+)/s) {
	# element
	&check_used("ATTLIST $1", $decl);
    } else {
	print STDERR "?? ", $decl, "\n";
	exit;
    }
}

sub check_used {
    my($thing, $decl) = @_;

#    print "\ncu: $thing == $decl\n";

    while ($decl =~ /%([^;]+)/) {
	$decl = $` . $';
	$changed = 1 if !$used{$1};
#	print "$thing uses $1\n";
	$used{$1} = 1;
    }
}

sub output {
    my($decl) = shift;

#    print "Output? $decl\n";

    if ($decl =~ /^ENTITY % (\S+)\s+(PUBLIC\s+\".*?\"|SYSTEM)\s+\"(.*?)\"/s) {
	my($ent) = $1;
	my($pub) = $2;
	my($sys) = $3;
	if (!exists($entity{$ent})) {
	    if (0 && $pub =~ /^PUBLIC\s+\"ISO/s) {
		print "\n<!", $decl, ">\n";
		print "\%$ent;\n";
	    } else {
		&read_dtd($3);
	    }
	}
    } elsif ($decl =~ /^ENTITY % (\S+)\s+([\'\"])(.*?)\2/s) {
	my($ent, $val) = ($1, $3);
#	print "ot: $ent = ", $used{$ent}, "\n";

	$decl = &trim_null($decl);

	if (!exists($entity{$ent})) {
	    if ($val ne '' || $ent =~ /^local\./) {
		print "<!", $decl, ">\n" if $used{$ent};
	    }
	    $entity{$ent} = $val;
	}
    } elsif ($decl =~ /^ENTITY\s+(\S+)\s+([\'\"])(.*?)\2/s) {
	my($ent, $val) = ($1, $3);

	if (!exists($entity{$ent})) {
	    if ($val ne '' || $ent =~ /^local\./) {
		print "<!", $decl, ">\n" if $used{$ent};
	    }
	    $entity{$ent} = $val;
	}
    } elsif ($decl =~ /^--.*?--/s) {
	# comment;
    } elsif ($decl =~ /^NOTATION\s+/) {
	# notation
	$decl = &trim_null($decl);
	print "<!", $decl, ">\n";
    } elsif ($decl =~ /^ELEMENT\s+/) {
	# element
	$decl = &trim_null($decl);
	print "<!", $decl, ">\n";
    } elsif ($decl =~ /^ATTLIST\s+/) {
	# element
	$decl = &trim_null($decl);
	print "<!", $decl, ">\n";
    } else {
	print STDERR "?? ", $decl, "\n";
	exit;
    }	
}

sub trim_null {
    my($decl) = shift;
    my($new) = "";
    my($ent);

    while ($decl =~ /^(.*?)%(\S[^;]+);?/s) {
	$new .= $1;
	$ent = $2;
	$decl = $';

#	print STDERR "entity{$ent} = $entity{$ent}\n";

	if ($entity{$ent} ne '' || $ent =~ /^local\./) {
	    $new .= "%$ent;";
	}
    }

    return $new . $decl;
}