# frozen_string_literal: true

require "rack/proxy"

# Public: Allows to relay asset requests to the Vite development server.
class ViteRuby::DevServerProxy < Rack::Proxy
  HOST_WITH_PORT_REGEX = %r{^(.+?)(:\d+)/}
  VITE_DEPENDENCY_PREFIX = "/@"

  def initialize(app = nil, options = {})
    @vite_ruby = options.delete(:vite_ruby) || ViteRuby.instance
    options[:streaming] = false if config.mode == "test" && !options.key?(:streaming)
    super
  end

  # Rack: Intercept asset requests and send them to the Vite server.
  def perform_request(env)
    if vite_should_handle?(env) && dev_server_running?
      forward_to_vite_dev_server(env)
      super
    else
      @app.call(env)
    end
  end

private

  extend Forwardable

  def_delegators :@vite_ruby, :config, :dev_server_running?

  def rewrite_uri_for_vite(env)
    uri = env.fetch("REQUEST_URI") { [env["PATH_INFO"], env["QUERY_STRING"]].reject { |str| str.to_s.strip.empty? }.join("?") }
    env["PATH_INFO"], env["QUERY_STRING"] = (env["REQUEST_URI"] = normalize_uri(uri)).split("?")
  end

  def normalize_uri(uri)
    uri
      .sub(HOST_WITH_PORT_REGEX, "/") # Hanami adds the host and port.
      .sub(".ts.js", ".ts") # Hanami's javascript helper always adds the extension.
      .sub(/\.(sass|scss|styl|stylus|less|pcss|postcss)\.css$/, '.\1') # Rails' stylesheet_link_tag always adds the extension.
  end

  def forward_to_vite_dev_server(env)
    rewrite_uri_for_vite(env)
    env["QUERY_STRING"] ||= ""
    env["HTTP_HOST"] = env["HTTP_X_FORWARDED_HOST"] = config.host
    env["HTTP_X_FORWARDED_SERVER"] = config.host_with_port
    env["HTTP_PORT"] = env["HTTP_X_FORWARDED_PORT"] = config.port.to_s
    env["HTTP_X_FORWARDED_PROTO"] = env["HTTP_X_FORWARDED_SCHEME"] = config.protocol
    env["HTTPS"] = env["HTTP_X_FORWARDED_SSL"] = "off" unless config.https
    env["SCRIPT_NAME"] = ""
  end

  def vite_should_handle?(env)
    path = normalize_uri(env["PATH_INFO"])
    return true if path.start_with?(vite_url_prefix) # Vite asset

    true if file_in_vite_root?(path) # Fallback if Vite can serve the file
  end

  # NOTE: When using an empty 'public_output_dir', we need to rely on a
  # filesystem check to check whether Vite should serve the request.
  def file_in_vite_root?(path)
    path.include?(".") && # Check for extension, avoid filesystem if possible.
      config.vite_root_dir.join(path.start_with?("/") ? path[1..] : path).file?
  end

  # NOTE: Vite is configured to use 'public_output_dir' as the base, which can
  # be customized by the user in development to not match any of the routes.
  #
  # If the path starts with that prefix, it will be redirected to Vite.
  def vite_url_prefix
    @vite_url_prefix ||= config.public_output_dir.empty? ? VITE_DEPENDENCY_PREFIX : "/#{config.public_output_dir}/"
  end
end