module Language
  module Node
    def self.npm_cache_config
      "cache=#{HOMEBREW_CACHE}/npm_cache\n"
    end

    def self.pack_for_installation
      # Homebrew assumes the buildpath/testpath will always be disposable
      # and from npm 5.0.0 the logic changed so that when a directory is
      # fed to `npm install` only symlinks are created linking back to that
      # directory, consequently breaking that assumption. We require a tarball
      # because npm install creates a "real" installation when fed a tarball.
      output = Utils.popen_read("npm pack").chomp
      raise "npm failed to pack #{Dir.pwd}" unless $CHILD_STATUS.exitstatus.zero?
      output
    end

    def self.setup_npm_environment
      npmrc = Pathname.new("#{ENV["HOME"]}/.npmrc")
      # only run setup_npm_environment once per formula
      return if npmrc.exist?
      # explicitly set npm's cache path to HOMEBREW_CACHE/npm_cache to fix
      # issues caused by overriding $HOME (long build times, high disk usage)
      # https://github.com/Homebrew/brew/pull/37#issuecomment-208840366
      npmrc.write npm_cache_config
      # explicitly use our npm and node-gyp executables instead of the user
      # managed ones in HOMEBREW_PREFIX/lib/node_modules which might be broken
      begin
        ENV.prepend_path "PATH", Formula["node"].opt_libexec/"bin"
      rescue FormulaUnavailableError
        nil
      end
    end

    def self.std_npm_install_args(libexec)
      setup_npm_environment
      # tell npm to not install .brew_home by adding it to the .npmignore file
      # (or creating a new one if no .npmignore file already exists)
      open(".npmignore", "a") { |f| f.write("\n.brew_home\n") }

      pack = pack_for_installation

      # npm install args for global style module format installed into libexec
      %W[
        --verbose
        --global
        --prefix=#{libexec}
        #{Dir.pwd}/#{pack}
      ]
    end

    def self.local_npm_install_args
      setup_npm_environment
      # npm install args for local style module format
      ["--verbose"]
    end
  end
end