#!/usr/bin/env ruby
# frozen_string_literal: true

require 'date'
require 'etc'
require 'logger'
require 'ipaddr'
require 'yaml'
require 'rack'
require 'rackup'
require 'erb'
require 'metriks'
require 'better_errors' if ENV.fetch('RACK_ENV', nil) == 'development'

require 'openvpn-status-web/status'
require 'openvpn-status-web/parser/v1'
require 'openvpn-status-web/parser/v2'
require 'openvpn-status-web/parser/v3'
require 'openvpn-status-web/int_patch'
require 'openvpn-status-web/version'

module OpenVPNStatusWeb
  # @return [Logger]
  def self.logger
    @logger
  end

  # @param logger [Logger]
  # @return [Logger]
  def self.logger=(logger)
    @logger = logger
  end

  class LogFormatter
    # @param lvl [Object]
    # @param _time [DateTime]
    # @param _progname [String]
    # @param msg [Object]
    # @return [String]
    def call(lvl, _time, _progname, msg)
      format("[%s] %-5s %s\n", Time.now.strftime('%Y-%m-%d %H:%M:%S'), lvl, msg.to_s)
    end
  end

  class Daemon
    def initialize(vpns)
      @vpns = vpns

      @main_tmpl = read_template(File.join(File.dirname(__FILE__), 'openvpn-status-web/main.html.erb'))
    end

    def call(env)
      return [405, {'Content-Type' => 'text/plain'}, ['Method Not Allowed']] if env['REQUEST_METHOD'] != 'GET'
      return [404, {'Content-Type' => 'text/plain'}, ['Not Found']] if env['PATH_INFO'] != '/'

      # variables for template
      vpns = @vpns
      stati = {}
      @vpns.each do |name, config|
        stati[name] = parse_status_log(config)
      end
      # eval
      html = @main_tmpl.result(binding)

      [200, {'Content-Type' => 'text/html'}, [html]]
    end

    def read_template(file)
      text = File.read(file, mode: 'rb')

      ERB.new(text)
    end

    def parse_status_log(vpn)
      text = File.read(vpn['status_file'], mode: 'rb')

      case vpn['version']
      when 1
        OpenVPNStatusWeb::Parser::V1.new.parse_status_log(text)
      when 2
        OpenVPNStatusWeb::Parser::V2.new.parse_status_log(text)
      when 3
        OpenVPNStatusWeb::Parser::V3.new.parse_status_log(text)
      else
        raise "No suitable parser for status-version #{vpn['version']}"
      end
    end

    # @return [void]
    def self.run!
      if ARGV.length != 1
        puts 'Usage: openvpn-status-web config_file'
        exit 1
      end

      config_file = ARGV[0]

      if !File.file?(config_file)
        puts 'Config file not found!'
        exit 1
      end

      puts "openvpn-status-web version #{OpenVPNStatusWeb::VERSION}"
      puts "Using config file #{config_file}"

      config = YAML.safe_load(File.read(config_file, mode: 'r'))

      if config['logfile']
        OpenVPNStatusWeb.logger = Logger.new(config['logfile'])
      else
        OpenVPNStatusWeb.logger = Logger.new($stdout)
      end

      OpenVPNStatusWeb.logger.progname = 'openvpn-status-web'
      OpenVPNStatusWeb.logger.formatter = LogFormatter.new

      OpenVPNStatusWeb.logger.info 'Starting...'

      # drop priviliges as soon as possible
      # NOTE: first change group than user
      if config['group']
        group = Etc.getgrnam(config['group'])
        Process::Sys.setgid(group.gid) if group
      end
      if config['user']
        user = Etc.getpwnam(config['user'])
        Process::Sys.setuid(user.uid) if user
      end

      # configure rack
      app = Daemon.new(config['vpns'])
      if ENV.fetch('RACK_ENV', nil) == 'development'
        app = BetterErrors::Middleware.new(app)
        BetterErrors.application_root = File.expand_path(__dir__)
      end

      Signal.trap('INT') do
        OpenVPNStatusWeb.logger.info 'Quitting...'
        Rackup::Handler::WEBrick.shutdown
      end
      Signal.trap('TERM') do
        OpenVPNStatusWeb.logger.info 'Quitting...'
        Rackup::Handler::WEBrick.shutdown
      end

      Rackup::Handler::WEBrick.run app, Host: config['host'], Port: config['port']
    end
  end
end