#!/usr/bin/perl
use strict;
use Text::Tabs;
use Getopt::Long;
use Pod::Usage;

my $debug;
my $help;
my $man;

GetOptions(
	"debug" => \$debug,
	'usage|?' => \$help,
	'help' => \$man
) or pod2usage(2);

pod2usage(1) if $help;
pod2usage(-exitstatus => 0, -verbose => 2) if $man;
pod2usage(2) if (scalar @ARGV < 2 || scalar @ARGV > 3);

my ($file_in, $file_out, $file_exceptions) = @ARGV;

my $data;
my %ioctls;
my %defines;
my %typedefs;
my %enums;
my %enum_symbols;
my %structs;

require Data::Dumper if ($debug);

#
# read the file and get identifiers
#

my $is_enum = 0;
my $is_comment = 0;
open IN, $file_in or die "Can't open $file_in";
while (<IN>) {
	$data .= $_;

	my $ln = $_;
	if (!$is_comment) {
		$ln =~ s,/\*.*(\*/),,g;

		$is_comment = 1 if ($ln =~ s,/\*.*,,);
	} else {
		if ($ln =~ s,^(.*\*/),,) {
			$is_comment = 0;
		} else {
			next;
		}
	}

	if ($is_enum && $ln =~ m/^\s*([_\w][\w\d_]+)\s*[\,=]?/) {
		my $s = $1;
		my $n = $1;
		$n =~ tr/A-Z/a-z/;
		$n =~ tr/_/-/;

		$enum_symbols{$s} =  "\\ :ref:`$s <$n>`\\ ";

		$is_enum = 0 if ($is_enum && m/\}/);
		next;
	}
	$is_enum = 0 if ($is_enum && m/\}/);

	if ($ln =~ m/^\s*#\s*define\s+([_\w][\w\d_]+)\s+_IO/) {
		my $s = $1;
		my $n = $1;
		$n =~ tr/A-Z/a-z/;

		$ioctls{$s} = "\\ :ref:`$s <$n>`\\ ";
		next;
	}

	if ($ln =~ m/^\s*#\s*define\s+([_\w][\w\d_]+)\s+/) {
		my $s = $1;
		my $n = $1;
		$n =~ tr/A-Z/a-z/;
		$n =~ tr/_/-/;

		$defines{$s} = "\\ :ref:`$s <$n>`\\ ";
		next;
	}

	if ($ln =~ m/^\s*typedef\s+([_\w][\w\d_]+)\s+(.*)\s+([_\w][\w\d_]+);/) {
		my $s = $2;
		my $n = $3;

		$typedefs{$n} = "\\ :c:type:`$n <$s>`\\ ";
		next;
	}
	if ($ln =~ m/^\s*enum\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*enum\s+([_\w][\w\d_]+)$/
	    || $ln =~ m/^\s*typedef\s*enum\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*typedef\s*enum\s+([_\w][\w\d_]+)$/) {
		my $s = $1;

		$enums{$s} =  "enum :c:type:`$s`\\ ";

		$is_enum = $1;
		next;
	}
	if ($ln =~ m/^\s*struct\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*struct\s+([[_\w][\w\d_]+)$/
	    || $ln =~ m/^\s*typedef\s*struct\s+([_\w][\w\d_]+)\s+\{/
	    || $ln =~ m/^\s*typedef\s*struct\s+([[_\w][\w\d_]+)$/
	    ) {
		my $s = $1;

		$structs{$s} = "struct :c:type:`$s`\\ ";
		next;
	}
}
close IN;

#
# Handle multi-line typedefs
#

my @matches = ($data =~ m/typedef\s+struct\s+\S+?\s*\{[^\}]+\}\s*(\S+)\s*\;/g,
	       $data =~ m/typedef\s+enum\s+\S+?\s*\{[^\}]+\}\s*(\S+)\s*\;/g,);
foreach my $m (@matches) {
	my $s = $m;

	$typedefs{$s} = "\\ :c:type:`$s`\\ ";
	next;
}

#
# Handle exceptions, if any
#

my %def_reftype = (
	"ioctl"   => ":ref",
	"define"  => ":ref",
	"symbol"  => ":ref",
	"typedef" => ":c:type",
	"enum"    => ":c:type",
	"struct"  => ":c:type",
);

if ($file_exceptions) {
	open IN, $file_exceptions or die "Can't read $file_exceptions";
	while (<IN>) {
		next if (m/^\s*$/ || m/^\s*#/);

		# Parsers to ignore a symbol

		if (m/^ignore\s+ioctl\s+(\S+)/) {
			delete $ioctls{$1} if (exists($ioctls{$1}));
			next;
		}
		if (m/^ignore\s+define\s+(\S+)/) {
			delete $defines{$1} if (exists($defines{$1}));
			next;
		}
		if (m/^ignore\s+typedef\s+(\S+)/) {
			delete $typedefs{$1} if (exists($typedefs{$1}));
			next;
		}
		if (m/^ignore\s+enum\s+(\S+)/) {
			delete $enums{$1} if (exists($enums{$1}));
			next;
		}
		if (m/^ignore\s+struct\s+(\S+)/) {
			delete $structs{$1} if (exists($structs{$1}));
			next;
		}
		if (m/^ignore\s+symbol\s+(\S+)/) {
			delete $enum_symbols{$1} if (exists($enum_symbols{$1}));
			next;
		}

		# Parsers to replace a symbol
		my ($type, $old, $new, $reftype);

		if (m/^replace\s+(\S+)\s+(\S+)\s+(\S+)/) {
			$type = $1;
			$old = $2;
			$new = $3;
		} else {
			die "Can't parse $file_exceptions: $_";
		}

		if ($new =~ m/^\:c\:(data|func|macro|type)\:\`(.+)\`/) {
			$reftype = ":c:$1";
			$new = $2;
		} elsif ($new =~ m/\:ref\:\`(.+)\`/) {
			$reftype = ":ref";
			$new = $1;
		} else {
			$reftype = $def_reftype{$type};
		}
		$new = "$reftype:`$old <$new>`";

		if ($type eq "ioctl") {
			$ioctls{$old} = $new if (exists($ioctls{$old}));
			next;
		}
		if ($type eq "define") {
			$defines{$old} = $new if (exists($defines{$old}));
			next;
		}
		if ($type eq "symbol") {
			$enum_symbols{$old} = $new if (exists($enum_symbols{$old}));
			next;
		}
		if ($type eq "typedef") {
			$typedefs{$old} = $new if (exists($typedefs{$old}));
			next;
		}
		if ($type eq "enum") {
			$enums{$old} = $new if (exists($enums{$old}));
			next;
		}
		if ($type eq "struct") {
			$structs{$old} = $new if (exists($structs{$old}));
			next;
		}

		die "Can't parse $file_exceptions: $_";
	}
}

if ($debug) {
	print Data::Dumper->Dump([\%ioctls], [qw(*ioctls)]) if (%ioctls);
	print Data::Dumper->Dump([\%typedefs], [qw(*typedefs)]) if (%typedefs);
	print Data::Dumper->Dump([\%enums], [qw(*enums)]) if (%enums);
	print Data::Dumper->Dump([\%structs], [qw(*structs)]) if (%structs);
	print Data::Dumper->Dump([\%defines], [qw(*defines)]) if (%defines);
	print Data::Dumper->Dump([\%enum_symbols], [qw(*enum_symbols)]) if (%enum_symbols);
}

#
# Align block
#
$data = expand($data);
$data = "    " . $data;
$data =~ s/\n/\n    /g;
$data =~ s/\n\s+$/\n/g;
$data =~ s/\n\s+\n/\n\n/g;

#
# Add escape codes for special characters
#
$data =~ s,([\_\`\*\<\>\&\\\\:\/\|\%\$\#\{\}\~\^]),\\$1,g;

$data =~ s,DEPRECATED,**DEPRECATED**,g;

#
# Add references
#

my $start_delim = "[ \n\t\(\=\*\@]";
my $end_delim = "(\\s|,|\\\\=|\\\\:|\\;|\\\)|\\}|\\{)";

foreach my $r (keys %ioctls) {
	my $s = $ioctls{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

foreach my $r (keys %defines) {
	my $s = $defines{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

foreach my $r (keys %enum_symbols) {
	my $s = $enum_symbols{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

foreach my $r (keys %enums) {
	my $s = $enums{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/enum\s+($r)$end_delim/$s$2/g;
}

foreach my $r (keys %structs) {
	my $s = $structs{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);

	$data =~ s/struct\s+($r)$end_delim/$s$2/g;
}

foreach my $r (keys %typedefs) {
	my $s = $typedefs{$r};

	$r =~ s,([\_\`\*\<\>\&\\\\:\/]),\\\\$1,g;

	print "$r -> $s\n" if ($debug);
	$data =~ s/($start_delim)($r)$end_delim/$1$s$3/g;
}

$data =~ s/\\ ([\n\s])/\1/g;

#
# Generate output file
#

my $title = $file_in;
$title =~ s,.*/,,;

open OUT, "> $file_out" or die "Can't open $file_out";
print OUT ".. -*- coding: utf-8; mode: rst -*-\n\n";
print OUT "$title\n";
print OUT "=" x length($title);
print OUT "\n\n.. parsed-literal::\n\n";
print OUT $data;
close OUT;

__END__

=head1 NAME

parse_headers.pl - parse a C file, in order to identify functions, structs,
enums and defines and create cross-references to a Sphinx book.

=head1 SYNOPSIS

B<parse_headers.pl> [<options>] <C_FILE> <OUT_FILE> [<EXCEPTIONS_FILE>]

Where <options> can be: --debug, --help or --man.

=head1 OPTIONS

=over 8

=item B<--debug>

Put the script in verbose mode, useful for debugging.

=item B<--usage>

Prints a brief help message and exits.

=item B<--help>

Prints a more detailed help message and exits.

=back

=head1 DESCRIPTION

Convert a C header or source file (C_FILE), into a ReStructured Text
included via ..parsed-literal block with cross-references for the
documentation files that describe the API. It accepts an optional
EXCEPTIONS_FILE with describes what elements will be either ignored or
be pointed to a non-default reference.

The output is written at the (OUT_FILE).

It is capable of identifying defines, functions, structs, typedefs,
enums and enum symbols and create cross-references for all of them.
It is also capable of distinguish #define used for specifying a Linux
ioctl.

The EXCEPTIONS_FILE contain two rules to allow ignoring a symbol or
to replace the default references by a custom one.

Please read Documentation/doc-guide/parse-headers.rst at the Kernel's
tree for more details.

=head1 BUGS

Report bugs to Mauro Carvalho Chehab <mchehab@s-opensource.com>

=head1 COPYRIGHT

Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab@s-opensource.com>.

License GPLv2: GNU GPL version 2 <http://gnu.org/licenses/gpl.html>.

This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

=cut