class Browser::Middleware

def assets?(request)
  request.path.match(ASSETS_REGEX)
end

def call(env)
  request = Rack::Request.new(env)
  # Only apply verification on HTML requests.
  # This ensures that images, CSS and JavaScript
  # will be rendered.
  return run_app(env) unless process?(request)
  path = catch(:redirected) do
    Context.new(request).instance_eval(&@block)
  end
  # No path, no match.
  return run_app(env) unless path
  resolve_redirection(env, request.path, path)
end

def html?(request)
  request.env["HTTP_ACCEPT"].to_s.match(ACCEPT_REGEX)
end

def initialize(app, &block)
  raise ArgumentError, "Browser::Middleware requires a block" unless block
  @app = app
  @block = block
end

def process?(request)
  html?(request) && !assets?(request)
end

def redirect(path)
  [302, {"Content-Type" => "text/html", "Location" => path}, []]
end

def resolve_redirection(env, current_path, path)
  uri = URI.parse(path)
  if uri.path == current_path
    run_app(env)
  else
    redirect(path)
  end
end

def run_app(env)
  @app.call(env)
end