CLASS {{p}}water_bill DEFINITION PUBLIC FINAL CREATE PUBLIC.
  PUBLIC SECTION.
    TYPES ty_amount TYPE p LENGTH 8 DECIMALS 2.

    METHODS constructor.

    METHODS calculate
      IMPORTING iv_consumption   TYPE i
                iv_days          TYPE i
      RETURNING VALUE(rv_amount) TYPE ty_amount.

  PRIVATE SECTION.
    DATA mo_tariff TYPE REF TO {{p}}water_tariff.

    METHODS consumption_charge
      IMPORTING iv_consumption   TYPE i
      RETURNING VALUE(rv_charge) TYPE ty_amount.

    METHODS sewage_charge
      IMPORTING iv_consumption_charge TYPE ty_amount
      RETURNING VALUE(rv_charge)      TYPE ty_amount.

    METHODS standing_charge
      IMPORTING iv_days          TYPE i
      RETURNING VALUE(rv_charge) TYPE ty_amount.

    METHODS tier_charge
      IMPORTING iv_from          TYPE i
                iv_to            TYPE i
                iv_price         TYPE {{p}}water_tariff=>ty_price
      RETURNING VALUE(rv_charge) TYPE ty_amount.
ENDCLASS.


CLASS {{p}}water_bill IMPLEMENTATION.
  METHOD constructor.
    mo_tariff = NEW {{p}}water_tariff( ).
  ENDMETHOD.

  METHOD calculate.
    DATA(lv_consumption_charge) = consumption_charge( iv_consumption ).
    DATA lv_net TYPE ty_amount.
    lv_net = lv_consumption_charge
           + sewage_charge( lv_consumption_charge )
           + standing_charge( iv_days ).
    DATA(lv_minimum) = mo_tariff->get_minimum_charge( ).
    IF lv_net < lv_minimum.
      rv_amount = lv_minimum.
    ELSE.
      rv_amount = lv_net.
    ENDIF.
  ENDMETHOD.

  METHOD consumption_charge.
    DATA(lt_tiers) = mo_tariff->get_tiers( ).
    DATA lv_from TYPE i.
    LOOP AT lt_tiers INTO DATA(ls_tier).
      DATA(lv_to) = COND i( WHEN ls_tier-limit_cbm = 0 OR ls_tier-limit_cbm > iv_consumption
                            THEN iv_consumption
                            ELSE ls_tier-limit_cbm ).
      rv_charge = rv_charge + tier_charge( iv_from  = lv_from
                                           iv_to    = lv_to
                                           iv_price = ls_tier-price_cbm ).
      lv_from = lv_to.
      IF lv_from >= iv_consumption.
        EXIT.
      ENDIF.
    ENDLOOP.
  ENDMETHOD.

  METHOD sewage_charge.
    DATA lv_product TYPE p LENGTH 16 DECIMALS 4.
    lv_product = iv_consumption_charge * mo_tariff->get_sewage_percent( ).
    rv_charge = lv_product / 100.
  ENDMETHOD.

  METHOD standing_charge.
    rv_charge = iv_days * mo_tariff->get_standing_charge( ).
  ENDMETHOD.

  METHOD tier_charge.
    DATA(lv_units) = iv_to - iv_from.
    IF lv_units > 0.
      rv_charge = lv_units * iv_price.
    ENDIF.
  ENDMETHOD.
ENDCLASS.