#!/usr/bin/perl

# Copyright (C) 2009  Neil Williams <codehelp@debian.org>

# This package is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

use Config::Auto;
use File::Basename;
use Emdebian::Tools;
use strict;
use warnings;
use vars qw/ $progname $our_version $vendor $package $key $cfile
 $config $value /;
$progname = basename($0);
$our_version = &tools_version();

sub usageversion {
	print(STDERR <<END)
$progname version $our_version

Usage:
$progname -V|--vendor VENDOR -p|--package PACKAGE -k|--key KEY
$progname -?|-h|--help|--version

Commands:
 -v|--vendor VENDOR:    the vendor name from dpkg-vendor
 -p|--package PACKAGE:  the package name (usually source)
 -k|--key KEY:          arbitrary string for the key of the data

All commands need to be specified.

On success, the string is printed and $progname exits with zero.

In the case of error, $progname dies with an empty string on STDERR
and exits with a non-zero return value.

END
		or die "$0: failed to write usage: $!\n";
}

while( @ARGV ) {
	$_= shift( @ARGV );
	last if m/^--$/;
	if (!/^-/) {
		unshift(@ARGV,$_);
		last;
	}
	elsif (/^(-\?|-h|--help|--version)$/) {
		&usageversion();
		exit (1);
	}
	elsif (/^(-V|--vendor)$/) {
		$vendor = shift;
	}
	elsif (/^(-p|--package)$/) {
		$package = shift;
	}
	elsif (/^(-k|--key)$/) {
		$key = shift;
	}
	else
	{
		&usageversion();
		die "unrecognised option:  $_.\n";
	}
}

# get the dpkg-vendor value.
$vendor = $ENV{"DEB_VENDOR"} if (defined $ENV{"DEB_VENDOR"});
chomp ($vendor) if (defined $vendor);

die ("\n") if ((not defined $vendor) or (not defined $package) or 
	(not defined $key));

# this is the real code.

$cfile = "/etc/emvendor.d/$vendor.conf";
die ("\n") if (not -f "$cfile");
$config = Config::Auto::parse("$cfile", format => "ini");
$value = $config->{"$package"}->{"$key"};
die ("\n") if (not defined $value);
print "$value\n";
exit (0);

# and we're done.

=pod

=head1 Name

emvendor - retrieve vendor-specific package configuration strings

=head1 Synopsis

 emvendor -V|--vendor VENDOR -p|--package PACKAGE -k|--key KEY
 emvendor -?|-h|--help|--version

=head1 Commands

 -v|--vendor VENDOR:    the vendor name from dpkg-vendor
 -p|--package PACKAGE:  the package name (usually source)
 -k|--key KEY:          arbitrary string for the key of the data

All commands must be specified every time.

On success, the string is printed and $progname exits with zero.

In the case of error, $progname dies with an empty string on STDERR
and exits with a non-zero return value.

=head1 Description

emvendor provides a way for debian/rules to call in a string for a
particular package that fits into the rules for that package B<and>
conforms to the requirements of the vendor.

http://wiki.debian.org/EmdebianAuditDetail#Vendor

It is fairly obvious that specifying each vendor in the F<debian/rules>
file of each package is not going to be particularly flexible.

 DEB_VENDOR=$(shell dpkg-vendor --query vendor)
 ifeq (Debian,$(DEB_VENDOR))
  # Debian build
  EXCONFARGS=--disable-mono --disable-monodoc
 else
  # any-vendor build
  EXCONFARGS=$(shell emvendor --vendor $(DEB_VENDOR) --package avahi --key EXCONFARGS)
 endif

or use the short options:

 EXCONFARGS=$(shell foo-bar -V $(DEB_VENDOR) -p avahi -k EXCONFARGS)

The values themselves are in a vendor-specific conf file in
F</etc/emvendor.d/>

 $ cat /etc/foo-bar.d/emdebian-crush
 [avahi]
 EXCONFARGS=--disable-mono --disable-monodoc --disable-python
 --disable-doxygen-doc --disable-pygtk --disable-python-dbus
 --disable-core-docs --disable-qt3 --disable-qt4 --disable-gobject
 --with-distro debian 

 [busybox]
 foo=

(Note that the value has to be all on one line which is a little
awkward - also note that values are not able to include the equals
sign which could be more of an issue.)

Packages that need two strings can do so - the key string is entirely
arbitrary as long as it fits in the style of a typical ini file.

Therefore, the key can be matched to the needs of the relevant package.

C<emdebian-buildsupport> provides F</etc/emvendor.d/emdebian-crush> with
all the content for all packages that need such details.

=head1 emvendor and dpkg-vendor

F<dpkg-vendor> supports vendor functionality but F<emvendor> adds an
extra hierarchy, organised by Debian source package name. It would be
possible to include the relevant strings in F</etc/dpkg/origins/vendor>
but each identifier string would need to be unique across all packages
for each vendor, which is an unrealistic limitation.

=cut