FUNCTION {{p}}meal_bill
  IMPORTING
    iv_week TYPE string
  EXPORTING
    ev_meals TYPE decfloat34
    ev_pupils TYPE decfloat34
    ev_amount TYPE decfloat34
    ev_discount TYPE decfloat34
  EXCEPTIONS
    invalid_price.

  TYPES:
    BEGIN OF ty_pupil_sum,
      pupil  TYPE string,
      meals  TYPE i,
      gross  TYPE decfloat34,
      amount TYPE decfloat34,
    END OF ty_pupil_sum.

  DATA lt_pupil TYPE SORTED TABLE OF ty_pupil_sum WITH UNIQUE KEY pupil.

  SELECT pupil, price, cancelled
    FROM {{P}}MEALBK
    WHERE week_key = @iv_week
    INTO TABLE @DATA(lt_book).

  LOOP AT lt_book INTO DATA(ls_book).
    IF ls_book-price < 0.
      RAISE invalid_price.
    ENDIF.
    IF ls_book-cancelled = 'X' OR ls_book-price = 0.
      CONTINUE.
    ENDIF.
    READ TABLE lt_pupil ASSIGNING FIELD-SYMBOL(<ls_pupil>) WITH TABLE KEY pupil = ls_book-pupil.
    IF sy-subrc <> 0.
      INSERT VALUE #( pupil = ls_book-pupil ) INTO TABLE lt_pupil ASSIGNING <ls_pupil>.
    ENDIF.
    <ls_pupil>-meals = <ls_pupil>-meals + 1.
    <ls_pupil>-gross = <ls_pupil>-gross + ls_book-price.
  ENDLOOP.

  LOOP AT lt_pupil ASSIGNING <ls_pupil>.
    <ls_pupil>-amount = <ls_pupil>-gross.
    IF <ls_pupil>-meals >= 5.
      <ls_pupil>-amount = round( val = <ls_pupil>-gross * 9 / 10
                                 dec = 2
                                 mode = cl_abap_math=>round_half_up ).
    ENDIF.
    ev_meals = ev_meals + <ls_pupil>-meals.
    ev_amount = ev_amount + <ls_pupil>-amount.
    ev_discount = ev_discount + <ls_pupil>-gross - <ls_pupil>-amount.
  ENDLOOP.

  ev_pupils = lines( lt_pupil ).

ENDFUNCTION.