class Course < ApplicationRecord
  has_many :lectures, dependent: :destroy
  has_many :work_items, dependent: :destroy

  # A course has a standalone connection to its recordings. To be displayed they must be associated with a lecture but
  # we them independently to avoid re-importing lectures.
  has_many :recordings, dependent: :destroy

  def lectures_and_work_items
    (lectures + work_items).sort_by(&:start_time)
  end

  def import_from_calendar!
    ics_file = HTTParty.get("https://mytimetable.bath.ac.uk/ical?6519757b&group=false&timetable=!MjAyMyFzdHVkZW50c2V0ITRDRjQ5MjlGRTg1M0Q4N0MyMDZENTVDNUQ3QTJFNzk0&eu=amMzMDkxQGJhdGguYWMudWs=&h=MiuDbRiudE_Yf7B25v2SfEuFCtmYGkFb5sAUI3yGmtY=")
    calendars = Icalendar::Calendar.parse(ics_file)
    calendar = calendars.first

    events = calendar.events.map do |event|
      summary = event.summary
      match = summary.split('-')

      # Handle odd events we don't care about
      next if match.length != 2

      unit_code = match[0]
      short_lecture_title = match[1]
      start_time = event.dtstart.to_time
      event_uuid = event.uid.to_s

      next if unit_code.nil? ||
        short_lecture_title.nil? ||
        event_uuid.nil? ||
        start_time.nil? ||
        unit_code != self.unit_code

      {
        unit_code:,
        short_lecture_title:,
        start_time:,
        event_uuid:,
      }
    end

    lecture_counter = 0

    events.compact.each do |event|
      # Naive check to see if we've already created this lecture
      if lectures.find_by(event_uuid: event[:event_uuid]).present? || lectures.find_by(
        start_time: (event[:start_time].beginning_of_hour + 5.minutes)..(event[:start_time].beginning_of_hour + 1.hour + 5.minutes)
      ).present?
        next
      end

      if event[:short_lecture_title].starts_with? "Lec"
        lecture_counter += 1
        title = "Lecture #{lecture_counter}"
      else
        title = event[:short_lecture_title]
      end

      lectures.create!(
        title: title,
        start_time: event[:start_time],
        event_uuid: event[:event_uuid],
      )
    end
  end

  # What should this do for existing attendances?
  def renumber_lectures!
    lectures.group_by(&:kind).each do |kind, lectures|
      lectures.sort_by(&:start_time).each_with_index do |lecture, index|
        lecture.update!(title: "#{kind.to_s.humanize} #{index + 1}")
      end
    end
  end
end