# frozen_string_literal: true

module MalawiHivProgramReports
  module Pepfar
    # This class is used to generate the TPT Status report for an ART patient
    class TptStatus
      attr_reader :start_date, :end_date, :patient_id

      include Utils

      def initialize(start_date:, end_date:, **kwargs)
        @start_date = start_date
        @end_date = end_date
        @patient_id = kwargs[:patient_id]
        @tpt_status = {}
      end

      def find_report
        patient_tpt_status
      rescue StandardError => e
        Rails.logger.error("Error generating TPT Status report for patient #{patient_id}: #{e.message}")
        Rails.logger.error(e.backtrace.join("\n"))
        raise e
      end

      private

      def patient_tpt_status
        return tb_treatment_status if patient_on_tb_treatment?(patient_id)
        return completed_tpt_status if patient_history_on_completed_tpt

        patient = TbPrev3.new(start_date:, end_date:).fetch_individual_report(patient_id)
        return default_status if patient.blank?

        tpt_status_based_on_patient(patient)
      end

      def tb_treatment_status
        {
          tpt: nil,
          completed: false,
          tb_treatment: true,
          tpt_init_date: nil,
          tpt_complete_date: nil,
          eligible: {
            '3HP': false,
            '6H': false
          }
        }
      end

      def completed_tpt_status
        tpt = patient_history_on_completed_tpt.include?('IPT') ? '6H' : '3HP'
        { tpt:, completed: true, tb_treatment: false, tpt_init_date: nil, tpt_complete_date: nil, tpt_end_date: nil,
          eligible: {
            '3HP': false,
            '6H': false
          } }
      end

      def default_status
        patient = ::Patient.find(patient_id)
        art_start_date = patient.art_start_date
        { tpt: nil, completed: false, tb_treatment: false, tpt_init_date: nil, tpt_complete_date: nil, tpt_end_date: nil,
          eligible: {
            '3HP': art_start_date ? difference_in_months(end_date.to_date, art_start_date.to_date) < 3 : true,
            '6H': art_start_date ? difference_in_months(end_date.to_date, art_start_date.to_date) < 3 : true
          } }
      end

      def tpt_status_based_on_patient(patient)
        tpt = determine_tpt(patient)
        completed = patient_has_totally_completed_tpt?(patient, tpt)
        tpt_init_date = patient['tpt_initiation_date']
        tpt_current_expiry_date = patient['auto_expire_date']&.to_date
        diff_in_months = difference_in_months(end_date.to_date, tpt_current_expiry_date)
        art_start_date = ::Patient.find(patient_id).art_start_date
        tpt_complete_date = completed ? patient['auto_expire_date']&.to_date : nil
        tpt_end_date = calculate_tpt_end_date(tpt, tpt_init_date)
        tpt_name = determine_tpt_name(tpt, patient)
        arv_drug_runout_date = patient_arv_drug_runout_date

        @tpt_status.merge!({ tpt: tpt_name, completed:, tb_treatment: false,
                             tpt_init_date:, tpt_complete_date:,
                             tpt_end_date:, art_start_date:,
                             art_drug_auto_expire_date: arv_drug_runout_date })
        determine_eligibility(tpt, diff_in_months, art_start_date, arv_drug_runout_date)
      end

      def determine_tpt(patient)
        patient_on_3hp?(patient) ? '3HP' : '6H'
      end

      def determine_tpt_name(tpt, patient)
        if tpt == '6H'
          'IPT'
        else
          (patient['drug_concepts'].split(',').length > 1 ? '3HP (RFP + INH)' : 'INH 300 / RFP 300 (3HP)')
        end
      end

      def calculate_tpt_end_date(tpt, tpt_init_date)
        tpt == '6H' ? tpt_init_date + 6.months : tpt_init_date + 3.months
      end

      def determine_eligibility(tpt, diff_in_months, art_start_date, arv_drug_runout_date)
        three_hp_eligible = false
        six_h_eligible = false
        tpt_init_date = @tpt_status[:tpt_init_date]
        tpt_end_date = @tpt_status[:tpt_end_date]
        case tpt
        when '3HP'
          # 3HP is taken 1 dose per week
          # if client misses dose for less than a month, they are eligible
          # if client misses more than a month:
          # check if they have been on ART for less than 3 months, they are eligible
          # if they have been on ART continuosly for more than 3 months, they are not eligible
          three_hp_eligible = true if diff_in_months <= 1
          if diff_in_months > 1 && (arv_drug_runout_date && difference_in_months(arv_drug_runout_date.to_date,
                                                                                 art_start_date.to_date) < 3)
            #  Patient defaulted for ART and TPT and was on ART for less than 3 months: patient TPT status is reset
            three_hp_eligible = true
            six_h_eligible = true
            tpt_end_date = nil
            tpt_init_date = nil
            @tpt_status[:tpt] = nil
          end
        when '6H'
          # 6H is taken 1 dose per day
          # if client misses dose for less than 2 months, they are eligible
          # if client misses more than a month:
          # check if they have been on ART for less than 3 months, they are eligible
          # if they have been on ART continuosly for more than 3 months, they are not eligible
          six_h_eligible = true if diff_in_months <= 2
          if diff_in_months > 2 && (arv_drug_runout_date && difference_in_months(arv_drug_runout_date.to_date,
                                                                                 art_start_date.to_date) < 3)
            #  Patient defaulted for ART and TPT and was on ART for less than 3 months: patient TPT status is reset
            three_hp_eligible = true
            six_h_eligible = true
            tpt_end_date = nil
            tpt_init_date = nil
            @tpt_status[:tpt] = nil
          end
        end
        @tpt_status.merge!({
                             tpt_init_date:,
                             tpt_end_date:,
                             eligible: {
                               '3HP': three_hp_eligible,
                               '6H': six_h_eligible
                             }
                           })
      end

      def patient_has_totally_completed_tpt?(patient, tpt)
        if tpt == '3HP'
          init_date = patient['tpt_initiation_date'].to_date
          end_date = patient['auto_expire_date'].to_date
          days_on_medication = (end_date - init_date).to_i
          days_on_medication >= 80
        else
          patient['total_days_on_medication'].to_i >= 176
        end
      end

      def patient_arv_drug_runout_date
        ::Patient.find(patient_id).last_arv_drug_expire_date
      end

      def patient_history_on_completed_tpt
        @patient_history_on_completed_tpt ||= ::Observation.where(person_id: patient_id,
                                                                  concept_id: ::ConceptName.find_by_name('Previous TB treatment history').concept_id)
                                                           .where("value_text LIKE '%complete%' AND obs_datetime < DATE('#{end_date}') + INTERVAL 1 DAY")&.first&.value_text
      end

      def difference_in_months(date1, date2)
        ((date1.year * 12) + date1.month) - ((date2.year * 12) + date2.month)
      end
    end
  end
end