FUNCTION {{p}}bike_rebalance
  IMPORTING
    iv_dry_run TYPE abap_bool
  EXPORTING
    ev_applied TYPE i
    ev_rejected TYPE i.

  DATA lt_state TYPE STANDARD TABLE OF {{p}}station.
  DATA lt_moves TYPE STANDARD TABLE OF {{p}}move.

  SELECT station_id, station_name, capacity, bikes
    FROM {{p}}station
    INTO TABLE @lt_state.

  SELECT move_no, source_id, target_id, quantity
    FROM {{p}}move
    INTO TABLE @lt_moves.

  SORT lt_state BY station_id.
  SORT lt_moves BY move_no.

  ev_applied = 0.
  ev_rejected = 0.

  LOOP AT lt_moves INTO DATA(ls_move).
    IF ls_move-quantity <= 0
       OR ls_move-source_id = ls_move-target_id.
      ev_rejected = ev_rejected + 1.
      CONTINUE.
    ENDIF.

    READ TABLE lt_state ASSIGNING FIELD-SYMBOL(<ls_source>)
      WITH KEY station_id = ls_move-source_id BINARY SEARCH.
    IF sy-subrc <> 0.
      ev_rejected = ev_rejected + 1.
      CONTINUE.
    ENDIF.

    READ TABLE lt_state ASSIGNING FIELD-SYMBOL(<ls_target>)
      WITH KEY station_id = ls_move-target_id BINARY SEARCH.
    IF sy-subrc <> 0.
      ev_rejected = ev_rejected + 1.
      CONTINUE.
    ENDIF.

    IF <ls_source>-bikes < ls_move-quantity
       OR <ls_target>-capacity - <ls_target>-bikes < ls_move-quantity.
      ev_rejected = ev_rejected + 1.
      CONTINUE.
    ENDIF.

    <ls_source>-bikes = <ls_source>-bikes - ls_move-quantity.
    <ls_target>-bikes = <ls_target>-bikes + ls_move-quantity.
    ev_applied = ev_applied + 1.
  ENDLOOP.

  IF iv_dry_run = abap_false.
    LOOP AT lt_state INTO DATA(ls_state).
      UPDATE {{p}}station
        SET bikes = @ls_state-bikes
        WHERE station_id = @ls_state-station_id.
    ENDLOOP.
  ENDIF.

ENDFUNCTION.