require 'icalendar/tzinfo'
class EventMailer < ApplicationMailer
 def send_invitation(_user, _event)

  # initialize a new icalendar class
  ical = Icalendar::Calendar.new

  # Define default time
  time_zone = 'UTC'
  cal_tz = TZInfo::Timezone.get time_zone

  # add timezone to icalendar 
  ical.add_timezone cal_tz

  # new icalendar event 
  event = Icalendar::Event.new

  # event start date
  event.dtstart = Icalendar::Values::DateTime.new _event.start_time, 'tzid' => cal_tz

  # event end date
  event.dtend = Icalendar::Values::DateTime.new _event.end_time, 'tzid' => cal_tz


  # event organizer
  event.organizer = Icalendar::Values::CalAddress.new("mailto:" + _user.email)

  # event created date
  event.created = DateTime.now

  # event location
  event.location =  _event.venue

  # if there's an external link e.g, google meet
  event.uid = event.url = _event.meeting_link


  # event title
  event.summary = _event.title


  # event description
  event.description = _event.description


  # attach the configured event to icalendar class
  ical.add_event(event)


  # protocol
  ical.append_custom_property("METHOD", "REQUEST")

  # this add's an attachment name `event.ics`, 
  # when clicked, the event gets added to the calendar. 

  mail.attachments['event.ics'] = { mime_type: 'application/ics', content: ical.to_ical }


  # send mail
  mail(to: _user.email, subject:  "#{_event.title} - #{_event.summary} ")
 end
end