# frozen_string_literal: true

require 'webrick'
require_relative 'logger'
require_relative 'core/locales'
require_relative 'core/haml_wrapper'
require_relative 'core/builder'
require_relative 'core/servlet'
require_relative 'core/version'
require_relative '../core_extensions'

# The main Intranet namespace.
module Intranet
  # The core of the Intranet.
  class Core
    # The port currently used by the Intranet.
    # @return [Integer]
    attr_reader :port

    # Initializes a new Intranet core instance. The first available port will be used, starting at
    # +preferred_port+. If +preferred_port+ port is 80 and the user has not enough priviledges to
    # use that port, port 8080 (or one of the following ports) will be used.
    # @param logger [Object] The logger.
    # @param preferred_port [Integer] The preferred port for the web server.
    def initialize(logger, preferred_port = 80)
      @logger = logger

      # Initialize translation module
      Intranet::Core::Locales.initialize

      # Initialize HAML wrapper
      Intranet::Core::HamlWrapper.initialize

      # Instanciate Intranet Builder and register page builders
      @builder = Intranet::Core::Builder.new(@logger)

      # Instanciate WebRick HTTP server
      @server = load_http_server(preferred_port)
      www_dir = File.join(__dir__, 'resources', 'www')
      mount_default_servlets(www_dir)
    end

    # Registers a new module to the core. The server must not be running. The module will then be
    # accessible through the given +path+ under the web server root.
    # @param responder [Intranet::AbstractResponder] The module responder instance.
    # @param path [Array] The path, relative to the web server root, representing the module root
    #                     directory. The path cannot be empty and have more than 2 elements. Each
    #                     element must only contain the following characters: +-_a-z0-9+.
    # @param resources_dir [String] The path to the directory that contains additional resources
    #                               required by the module. This directory should contain three
    #                               subdirectories: +haml/+, +locales/+ and +www/+. The +www/+ is
    #                               mounted under +<path>/design+ on the web server.
    # @raise [ArgumentError] If the +path+ is not valid.
    # @raise [Errno::EALREADY] If the server is already running.
    def register_module(responder, path, resources_dir = responder.resources_dir)
      raise Errno::EALREADY if @server.status != :Stop

      @builder.register(responder, path)
      module_add_servlet(path.empty? ? ['home'] : path, resources_dir)
      module_add_locales(resources_dir)
      module_add_haml_templates(resources_dir)
    end

    # Defines the URL of the home page.
    # @param url [String] The absolute URL of the home page.
    # @raise [ArgumentError] If the URL is not an absolute path.
    def home_url=(url)
      @builder.home_url = url
    end

    # Starts the web server.
    def start
      @logger.info('Intranet::Core: using locale \'' + I18n.default_locale.to_s + '\'')
      @logger.info('Intranet::Core: running Intranet version ' + VERSION)
      # Start serving HTTP requests
      @server.start
    end

    # Stops the web server and finalizes all registered module responders.
    def stop
      @logger.info('Intranet::Runner: requesting system shutdown...')
      @server.shutdown
      @builder.finalize
      @logger.close
    end

    private

    # See https://github.com/nahi/webrick/blob/master/lib/webrick/accesslog.rb#L69
    ACCESSLOG_FMT = "%h '%r' -> %s (%b bytes in %Ts)"

    def load_http_server(preferred_port)
      @port = preferred_port
      begin
        WEBrick::HTTPServer.new(Port: @port, Logger: @logger, AccessLog: [[@logger, ACCESSLOG_FMT]])
      rescue Errno::EACCES # not enough permission to use port 80
        @port = 8080
        retry
      rescue Errno::EADDRINUSE
        @port += 1
        retry
      end
    end

    def mount_default_servlets(www_dir)
      # Configure handlers for HTTP server
      # Start serving www/ as HTTP server root "/" using the class WEBrick::HTTPServlet::FileHandler
      # You can write your own servlet (it must inherit from WEBrick::HTTPServlet::AbstractServlet)
      # http://ruby-doc.org/stdlib-1.9.3/libdoc/webrick/rdoc/WEBrick/HTTPServlet/AbstractServlet.html
      # https://www.igvita.com/2007/02/13/building-dynamic-webrick-servers-in-ruby/
      @server.mount('/design', WEBrick::HTTPServlet::FileHandler, www_dir)
      @server.mount('/', Intranet::Core::Servlet, @builder)
    end

    def module_add_servlet(path, resources_dir)
      @server.mount('/' + path.join('/') + '/design',
                    WEBrick::HTTPServlet::FileHandler,
                    File.join(resources_dir, 'www'))
    end

    def module_add_locales(resources_dir)
      Intranet::Core::Locales.add_path(File.join(resources_dir, 'locales'))
    end

    def module_add_haml_templates(resources_dir)
      Intranet::Core::HamlWrapper.add_path(File.join(resources_dir, 'haml'))
    end
  end
end