require 'mkmf'

def gsl_config_arg(arg)
  yield arg_config("--with-gsl-#{arg}") {
    sh = 'sh ' if RUBY_PLATFORM =~ /mingw/
    IO.popen("#{sh}gsl-config --#{arg}") { |f| f.gets.chomp }
  }, lambda { |val| puts "checking gsl #{arg}... #{val}"; val }
rescue => err
  abort "*** ERROR: missing required library to compile this module: #{err}"
end

def gsl_def(const, value = nil)
  value = "=#{value}" if value
  $defs << "-D#{const}#{value}"
end

def gsl_have_header(library, header)
  have_library(library) if have_header(header)
end

def gsl_have_library(func)
  have_func(func) if have_library('gsl', func)
end

def gsl_dir_config(target, idir = nil, ldir = idir)
  dir_config(target, idir || $sitearchdir, ldir || $sitearchdir)
end

def gsl_gem_config(target, dir = 'ext')
  path = begin
    require 'rubygems'

    spec = Gem::Specification.find_by_path("#{target}.h")
    File.join(spec.full_gem_path, dir) if spec
  rescue LoadError
  end

  gsl_dir_config(target, path)

  $LOCAL_LIBS += " -l:#{target}.so" if arg_config("--force-link-#{target}")   ||
                                       $CFLAGS.include?('-Wl,--no-undefined') ||
                                       $LDFLAGS.include?('-Wl,--no-undefined')
end

$CFLAGS += ' -Wall -Iinclude'

gsl_config_arg(:version) { |version, check|
  gsl_def(:GSL_VERSION, check[version])

  ver = version.split('.').map { |x| x.to_i }

  later = lambda { |other|
    ary = other.split('.').map { |x| x.to_i }

    gte = ver[0] > ary[0] ? true  :
          ver[0] < ary[0] ? false :
          ver[1] > ary[1] ? true  :
          ver[1] < ary[1] ? false :
          ver.size < ary.size ? false :
          ver.size == 3 && ary.size == 3 ? ver[2] >= ary[2] : true

    ary.pop && ary[-1] += 1 if ary.last == 90

    gte && gsl_def("GSL_#{ary.join('_')}_LATER")
  }

  raise 'Ruby/GSL requires gsl-1.15 or later.' unless later['1.15']

  %w[1.15 1.16].each { |v| later[v] }
}

gsl_config_arg(:cflags) { |cflags, check|
  $CFLAGS += ' ' + check[cflags]
}

gsl_config_arg(:libs) { |libs, check|
  libs.tr!(File::PATH_SEPARATOR, ' ')

  if enable_config('atlas')
    dir_config('cblas')
    dir_config('atlas')

    if have_library('cblas') && have_library('atlas')
      libs.gsub!('-lgslcblas', '-lcblas -latlas')
    end
  end

  $LOCAL_LIBS += ' ' + check[libs]
}

have_func('round')

%w[alf qrngextra rngextra tensor].each { |library|
  gsl_have_header(library, "#{library}/#{library}.h")
}

gsl_have_header('bundle_method', 'gsl/gsl_multimin_fsdf.h')
gsl_have_header('cqp',           'gsl/gsl_cqp.h')
gsl_have_header('jacobi',        'jacobi.h')
gsl_have_header('ndlinear',      'ndlinear/gsl_multifit_ndlinear.h')
gsl_have_header('ool',           'ool/ool_version.h')

gsl_have_library('gsl_eigen_francis')
gsl_have_library('gsl_poly_solve_quartic')

gsl_def(:HAVE_GNU_GRAPH) if find_executable('graph')

gsl_gem_config('narray', 'src')

have_header('narray.h')
have_library('narray') if RUBY_PLATFORM =~ /cygwin|mingw/

unless arg_config('--disable-tamu-anova')
  gsl_dir_config('tamu_anova')
  gsl_have_header('tamuanova', 'tamu_anova/tamu_anova.h')
end

create_makefile('gsl_native')