class CustomStaticMiddleware
  def initialize(app, domain_map)
    @app = app
    @domain_map = domain_map
  end

  def call(env)
    request = Rack::Request.new(env)
    host = request.host

    if (target_path = find_mapped_path(host, request.path))
      env["PATH_INFO"] = target_path
    end

    @app.call(env)
  end

  private

  def find_mapped_path(host, path)
    @domain_map.each do |domain_pattern, subdirectory|
      matcher = "#{host}#{path}"
      return "#{subdirectory}#{path}" if matcher.match?(domain_pattern)
    end

    nil
  end
end