FUNCTION {{p}}guard_fee
  IMPORTING
    iv_shift_type TYPE string
    iv_hours TYPE decfloat34
  EXPORTING
    ev_surcharge TYPE abap_bool
  CHANGING
    cv_fee TYPE decfloat34
  EXCEPTIONS
    invalid_hours.

  CONSTANTS c_base_rate TYPE decfloat34 VALUE '25.50'.
  CONSTANTS c_night_factor TYPE decfloat34 VALUE '1.25'.
  CONSTANTS c_holiday_factor TYPE decfloat34 VALUE '2.00'.
  CONSTANTS c_min_fee TYPE decfloat34 VALUE '50.00'.

  DATA lv_known TYPE abap_bool.

  ev_surcharge = abap_false.

  IF iv_hours <= 0.
    RAISE invalid_hours.
  ENDIF.

  CASE iv_shift_type.
    WHEN 'DAY'.
      lv_known = abap_true.
      cv_fee = round( val = iv_hours * c_base_rate dec = 2 ).
    WHEN 'NIGHT'.
      lv_known = abap_true.
      ev_surcharge = abap_true.
      cv_fee = round( val = iv_hours * c_base_rate * c_night_factor dec = 3 ).
    WHEN 'HOLIDAY'.
      lv_known = abap_true.
      ev_surcharge = abap_true.
      cv_fee = round( val = iv_hours * c_base_rate * c_holiday_factor dec = 2 ).
    WHEN OTHERS.
      cv_fee = 0.
  ENDCASE.

  IF lv_known = abap_true AND cv_fee < c_min_fee.
    cv_fee = c_min_fee.
  ENDIF.

ENDFUNCTION.