module ThinkFeelDoEngine
  module Reports
    # Scenario: a Participant starts viewing a Lesson.
    class LessonViewing
      include LessonModule

      DEFAULT_LESSON_MODULE_POSTFIX = /\/providers\/.*/

      def self.columns
        %w( participant_id lesson_id page_headers lesson_selected_at
            last_page_number_opened last_page_opened_at )
      end

      def self.participant_ids(ids)
        ids.empty? ? Participant.ids : ids
      end

      def self.all(*ids)
        lessons = lesson_entries_map
        lessons_default = lessons_with_default_urls

        Participant.select(:id, :study_id)
          .where(id: participant_ids(ids)).map do |participant|
          lesson_select_events =
            EventCapture::Event
            .where(participant_id: participant.id, kind: "render")
            .select(:participant_id, :emitted_at, :payload)
            .to_a.select do |e|
              lessons.keys.include?(e.current_url.gsub(URL_ROOT_RE, "")) ||
              lessons_default
              .keys.include?(e.current_url.gsub(URL_ROOT_RE, ""))
            end

          lesson_select_events.map do |e|
            lesson_id = lessons[e.current_url.gsub(URL_ROOT_RE, "")] ||
                        lessons_default[e.current_url
                                        .gsub(URL_ROOT_RE, "")]
            last_page_opened = last_page_opened(e, lesson_id)
            event_hash(participant, lesson_id, e, last_page_opened)
          end
        end.flatten
      end

      # last event (click) with matching module id
      def self.last_page_opened(first_session_event, lesson_id)
        lesson_events =
          EventCapture::Event
          .where(participant_id: first_session_event.participant_id,
                 kind: "render")
          .where("emitted_at > ?", first_session_event.emitted_at)
          .order(:emitted_at)
          .select(:kind, :emitted_at, :payload)
          .to_a.take_while { |e| e.current_url.include?(lesson_id.to_s) }
        last_event = (lesson_events.last || first_session_event)

        {
          number: event_lesson_page_number(last_event),
          opened_at: last_event.emitted_at
        }
      end

      def self.event_lesson_page_number(event)
        if event.current_url.include? "providers"
          event.current_url[/\d+$/]
        else
          1
        end
      end

      def self.lessons_with_default_urls
        lessons_with_default_path = lesson_entries_map.each.map do |lesson|
          default_lesson_url =
            lesson[0].gsub(URL_ROOT_RE, "")
            .gsub(DEFAULT_LESSON_MODULE_POSTFIX, "")
          [default_lesson_url, lesson[1]]
        end
        Hash[lessons_with_default_path]
      end

      def self.event_hash(participant, lesson_id, event, last_page_opened)
        {
          participant_id: participant.study_id,
          lesson_id: lesson_id,
          page_headers: event.headers,
          lesson_selected_at: event.emitted_at.iso8601,
          last_page_number_opened: last_page_opened[:number].to_i,
          last_page_opened_at: last_page_opened[:opened_at].iso8601
        }
      end
    end
  end
end