use alienfile;
use Path::Tiny qw( path );

# Because bzip2 does not come with a pkg-config compatible .pc file
# we use the CBuilder plugin to guess the appropriate flags
# (usually just libs=-lbz2):
plugin 'Probe::CBuilder' => (
  libs    => '-lbz2',
  
  # The version regex here will attempt to parse out the
  # bzip2 version number from the output of the test program below.
  version => qr/version = '(.*?)[,']/,
  
  # Both the test program and the version regex are optional, but
  # if you do not provide them, then you should provide a 
  # sys { gather } declaration for how to obtain the version number.
  # assuming the version number matters.
  program => q{
#include <stdio.h>
#include <bzlib.h>

int main(int argc, char *argv[])
{
  printf("version = '%s'\n", BZ2_bzlibVersion());
  return 0;
}
},
);

# in addition to the library, we require that the bzip2 command
# is also available.
plugin 'Probe::CommandLine' => (
  command   => 'bzip2',
  secondary => 1,
);

share {

  # items in the share block relate to building the package
  # from source.  It is called share because it will be
  # installed into a dist level share directory in your
  # perl lib.

  # The Build::MSYS plugin just makes sure that Alien::MSYS
  # is used to provide the necessary tools on Windows.  It
  # doesn't do anything on other platforms.
  plugin 'Build::MSYS';

  # The Download negotiator picks the best method for
  # downloading the package.  It uses the version
  # regex to parse out the version number from the
  # tarball so that it can pick the most recent
  # version.
  start_url 'http://www.bzip.org/downloads.html';
  plugin 'Download' => (
    version => qr/^bzip2-([0-9\.]+)tar.gz$/,
  );

  # The Extract negotiator picks the best method for
  # extracting from the tarball.  We give it a hint
  # here that we expect the tarball to be .gz compressed
  # in case it needs to load extra modules to 
  # decompress.
  plugin Extract => 'tar.gz';

  # The build stage here is specified as a series of commands.
  # bzip2 uses make to build and install.  It is vital that we
  # include cccdlflags in the compiler flags, because this will
  # include any flags necessary for making the library relocatable
  # which we need to link into a Perl XS .so file.
  # We also use CC=$Config{cc} to make sure that we use the
  # same compiler as was used to build Perl.
  build [
    [ '%{make}', 'all', "CC=%{perl.config.cc}", "CFLAGS=%{perl.config.cccdlflags} %{perl.config.optimize}", ],
    [ '%{make}', 'install', 'PREFIX=%{.install.prefix}',                                                    ],
    
    # we can use a code ref here to determine the version number of
    # bzip2 from the directory that is extracted from the tarball.
    # Usually this is something like bzip2-1.0.6 and we just parse
    # off the bit that looks like a version number.
    sub {
      my($build) = @_;
      my($version) = path(".")->absolute->basename =~ /([0-9\.]+)$/;
      $build->runtime_prop->{version} = $version;
    },
  ];

  # The gather stage determines the appropriate cflags and libs for
  # using the library that we just built.
  gather sub {
    my($build) =@_;
    my $prefix = $build->runtime_prop->{prefix};
    $build->runtime_prop->{cflags}        = "-I$prefix/include";
    $build->runtime_prop->{cflags_static} = "-I$prefix/include";
    $build->runtime_prop->{libs}          = "-L$prefix/lib -lbz2";
    $build->runtime_prop->{libs_static}   = "-L$prefix/lib -lbz2";
  };

};
