class PackageConfig

def compute_default_path
  default_paths = nil
  if native_pkg_config
    pc_path = run_command(native_pkg_config.to_s,
                          "--variable=pc_path",
                          "pkg-config")
    if pc_path
      default_paths = pc_path.strip.split(SEPARATOR)
      default_paths = nil if default_paths.empty?
    end
  end
  if default_paths.nil?
    arch_depended_path = Dir.glob("/usr/lib/*/pkgconfig")
    default_paths = []
    pkg_config_prefix = native_pkg_config_prefix
    if pkg_config_prefix
      pkg_config_arch_depended_paths =
        Dir.glob((pkg_config_prefix + "lib/*/pkgconfig").to_s)
      default_paths.concat(pkg_config_arch_depended_paths)
      default_paths << (pkg_config_prefix + "lib64/pkgconfig").to_s
      default_paths << (pkg_config_prefix + "libx32/pkgconfig").to_s
      default_paths << (pkg_config_prefix + "lib/pkgconfig").to_s
      default_paths << (pkg_config_prefix + "libdata/pkgconfig").to_s
      default_paths << (pkg_config_prefix + "share/pkgconfig").to_s
    end
    conda_prefix = ENV["CONDA_PREFIX"]
    if conda_prefix
      default_paths << File.join(conda_prefix, "lib", "pkgconfig")
    end
    default_paths << "/usr/local/lib64/pkgconfig"
    default_paths << "/usr/local/libx32/pkgconfig"
    default_paths << "/usr/local/lib/pkgconfig"
    default_paths << "/usr/local/libdata/pkgconfig"
    default_paths << "/usr/local/share/pkgconfig"
    default_paths << "/opt/local/lib/pkgconfig"
    default_paths.concat(arch_depended_path)
    default_paths << "/usr/lib64/pkgconfig"
    default_paths << "/usr/libx32/pkgconfig"
    default_paths << "/usr/lib/pkgconfig"
    default_paths << "/usr/libdata/pkgconfig"
    default_paths << "/usr/X11R6/lib/pkgconfig"
    default_paths << "/usr/X11R6/share/pkgconfig"
    default_paths << "/usr/X11/lib/pkgconfig"
    default_paths << "/opt/X11/lib/pkgconfig"
    default_paths << "/usr/share/pkgconfig"
  end
  if Object.const_defined?(:RubyInstaller)
    mingw_bin_path = RubyInstaller::Runtime.msys2_installation.mingw_bin_path
    mingw_pkgconfig_path = Pathname.new(mingw_bin_path) + "../lib/pkgconfig"
    default_paths.unshift(mingw_pkgconfig_path.cleanpath.to_s)
  end
  libdir = ENV["PKG_CONFIG_LIBDIR"]
  default_paths.unshift(libdir) if libdir
  paths = []
  if /-darwin\d[\d\.]*\z/ =~ RUBY_PLATFORM and
    /\A(\d+\.\d+)/ =~ run_command("sw_vers", "-productVersion")
    mac_os_version = $1
    homebrew_repository_candidates = []
    if pkg_config_prefix
      brew_path = pkg_config_prefix + "bin" + "brew"
      if brew_path.exist?
        homebrew_repository = run_command(brew_path.to_s, "--repository")
        if homebrew_repository
          homebrew_repository_candidates <<
            Pathname.new(homebrew_repository.strip)
        end
      else
        homebrew_repository_candidates << pkg_config_prefix + "Homebrew"
        homebrew_repository_candidates << pkg_config_prefix
      end
    end
    brew = search_executable_from_path("brew")
    if brew
      homebrew_repository = run_command("brew", "--repository")
      if homebrew_repository
      homebrew_repository_candidates <<
        Pathname(homebrew_repository.to_s)
      end
    end
    homebrew_repository_candidates.uniq.each do |candidate|
      pkgconfig_base_path = candidate + "Library/Homebrew/os/mac/pkgconfig"
      path = pkgconfig_base_path + mac_os_version
      unless path.exist?
        path = pkgconfig_base_path + mac_os_version.gsub(/\.\d+\z/, "")
      end
      paths << path.to_s if path.exist?
    end
  end
  paths.concat(default_paths)
  paths.join(SEPARATOR)
end