# frozen_string_literal: true

require 'uri'
require 'webrick'
require 'webrick/httpstatus'

module Intranet
  class Core
    # @!visibility protected
    # WEBrick servlet for the Intranet.
    class Servlet < WEBrick::HTTPServlet::AbstractServlet
      # Initializes a new Servlet instance.
      # @param server [WEBrick::HTTPServer] The web server.
      # @param builder [Intranet::Core::Builder] The web pages builder.
      def initialize(server, builder)
        super(server)
        @builder = builder
      end

      # Processes a GET request issued to the web server.
      # @param request [WEBrick::HTTPRequest] The GET request.
      # @param response [WEBrick::HTTPResponse] Fields +status+, +content_type+ and +body+ are
      #                                         filled with the server response.
      def do_GET(request, response) # rubocop:disable Naming/MethodName
        # See https://github.com/nahi/webrick/blob/master/lib/webrick/httprequest.rb
        # We could use request.request_uri (which is a URI object) but its path is not normalized
        # (it may contain '../' or event start with '..'). Hence we use request.path which has been
        # normalized with HTTPUtils::normalize_path, and request.query for the URL parameters.
        path = request.path.force_encoding('UTF-8')
        path += 'index.html' if path.end_with?('/')

        handle_redirections(request, path, response, '/index.html' => @builder.home_url)

        status, content_type, body = @builder.do_get(path, encode_query(request.query))

        raise WEBrick::HTTPStatus[status] if WEBrick::HTTPStatus.error?(status)

        response.status = status
        response.content_type = content_type
        response.body = body
      end

      private

      # Issues an HTTP redirection (307) in +response+ if the +path+ associated to the +request+
      # has an entry if the redirection table +redirects+.
      def handle_redirections(request, path, response, redirects)
        target = redirects.fetch(path)
        location = URI.join(request.request_uri, target).to_s
        response.set_redirect(WEBrick::HTTPStatus[307], location) if path != target
      rescue KeyError
        # nothing to do
      end

      # Reencodes the +query+ in UTF-8 strings for compatibility.
      def encode_query(query)
        query.map do |k, v|
          { k.dup.force_encoding('UTF-8') => v.force_encoding('UTF-8') }
        end.reduce({}, :merge)
      end
    end
  end
end