CLASS {{p}}rack_billing DEFINITION PUBLIC FINAL CREATE PUBLIC.
  PUBLIC SECTION.
    TYPES ty_size TYPE c LENGTH 1.
    TYPES ty_power TYPE c LENGTH 1.
    TYPES ty_customer TYPE c LENGTH 10.
    TYPES ty_fee TYPE p LENGTH 8 DECIMALS 2.

    TYPES:
      BEGIN OF ty_rack,
        rack_id     TYPE c LENGTH 10,
        customer    TYPE ty_customer,
        size_class  TYPE ty_size,
        power_class TYPE ty_power,
      END OF ty_rack.
    TYPES tt_racks TYPE STANDARD TABLE OF ty_rack WITH EMPTY KEY.

    TYPES:
      BEGIN OF ty_bill,
        customer   TYPE ty_customer,
        rack_count TYPE i,
        total_fee  TYPE ty_fee,
      END OF ty_bill.
    TYPES tt_bills TYPE STANDARD TABLE OF ty_bill WITH EMPTY KEY.

    METHODS calculate
      IMPORTING it_racks        TYPE tt_racks
      RETURNING VALUE(rt_bills) TYPE tt_bills.

  PRIVATE SECTION.
    TYPES:
      BEGIN OF ty_price,
        size_class  TYPE ty_size,
        power_class TYPE ty_power,
        fee         TYPE ty_fee,
      END OF ty_price.
    TYPES tt_prices TYPE HASHED TABLE OF ty_price WITH UNIQUE KEY size_class power_class.
    TYPES tt_seen TYPE HASHED TABLE OF ty_rack WITH UNIQUE KEY rack_id.
    TYPES tt_bill_hash TYPE HASHED TABLE OF ty_bill WITH UNIQUE KEY customer.

    METHODS price_list
      RETURNING VALUE(rt_prices) TYPE tt_prices.
    METHODS rack_fee
      IMPORTING is_rack       TYPE ty_rack
                it_prices     TYPE tt_prices
      RETURNING VALUE(rv_fee) TYPE ty_fee.
    METHODS discount_percent
      IMPORTING iv_count         TYPE i
      RETURNING VALUE(rv_percent) TYPE i.
ENDCLASS.


CLASS {{p}}rack_billing IMPLEMENTATION.
  METHOD calculate.
    DATA(lt_prices) = price_list( ).
    DATA lt_seen TYPE tt_seen.
    DATA lt_bills TYPE tt_bill_hash.

    LOOP AT it_racks INTO DATA(ls_rack).
      INSERT ls_rack INTO TABLE lt_seen.
      IF sy-subrc <> 0.
        CONTINUE.
      ENDIF.

      DATA(lv_fee) = rack_fee( is_rack = ls_rack it_prices = lt_prices ).
      IF lv_fee IS INITIAL.
        CONTINUE.
      ENDIF.

      ASSIGN lt_bills[ customer = ls_rack-customer ] TO FIELD-SYMBOL(<ls_bill>).
      IF sy-subrc <> 0.
        INSERT VALUE #( customer = ls_rack-customer ) INTO TABLE lt_bills ASSIGNING <ls_bill>.
      ENDIF.
      <ls_bill>-rack_count = <ls_bill>-rack_count + 1.
      <ls_bill>-total_fee = <ls_bill>-total_fee + lv_fee.
    ENDLOOP.

    LOOP AT lt_bills ASSIGNING <ls_bill>.
      DATA(lv_percent) = discount_percent( <ls_bill>-rack_count ).
      <ls_bill>-total_fee = <ls_bill>-total_fee / ( 100 - lv_percent ) / 100.
      INSERT VALUE #( customer   = <ls_bill>-customer
                      rack_count = <ls_bill>-rack_count
                      total_fee  = <ls_bill>-total_fee ) INTO TABLE rt_bills.
    ENDLOOP.

    SORT rt_bills BY customer.
  ENDMETHOD.

  METHOD price_list.
    rt_prices = VALUE #(
      ( size_class = 'S' power_class = 'A' fee = '50.00' )
      ( size_class = 'S' power_class = 'B' fee = '80.00' )
      ( size_class = 'S' power_class = 'C' fee = '120.00' )
      ( size_class = 'M' power_class = 'A' fee = '120.00' )
      ( size_class = 'M' power_class = 'B' fee = '150.00' )
      ( size_class = 'M' power_class = 'C' fee = '190.00' )
      ( size_class = 'L' power_class = 'A' fee = '250.00' )
      ( size_class = 'L' power_class = 'B' fee = '280.00' )
      ( size_class = 'L' power_class = 'C' fee = '320.00' ) ).
  ENDMETHOD.

  METHOD rack_fee.
    ASSIGN it_prices[ size_class = is_rack-size_class power_class = is_rack-power_class ]
           TO FIELD-SYMBOL(<ls_price>).
    IF sy-subrc = 0.
      rv_fee = <ls_price>-fee.
    ENDIF.
  ENDMETHOD.

  METHOD discount_percent.
    IF iv_count >= 20.
      rv_percent = 20.
    ELSEIF iv_count >= 10.
      rv_percent = 10.
    ENDIF.
  ENDMETHOD.
ENDCLASS.