CLASS {{p}}cold_chain_check DEFINITION PUBLIC FINAL CREATE PUBLIC.
  PUBLIC SECTION.
    TYPES: BEGIN OF ty_reading,
             offset_min  TYPE i,
             temp_tenths TYPE i,
           END OF ty_reading,
           tt_readings TYPE STANDARD TABLE OF ty_reading WITH EMPTY KEY,
           BEGIN OF ty_config,
             min_tenths   TYPE i,
             max_tenths   TYPE i,
             min_duration TYPE i,
             max_gap      TYPE i,
           END OF ty_config.

    METHODS constructor
      IMPORTING is_config TYPE ty_config.

    METHODS check
      IMPORTING it_readings    TYPE tt_readings
      RETURNING VALUE(rv_mean) TYPE i
      RAISING   {{p}}cx_cold_chain.

  PRIVATE SECTION.
    DATA ms_config TYPE ty_config.

    METHODS first_violation
      IMPORTING it_readings    TYPE tt_readings
      RETURNING VALUE(rv_rule) TYPE string.
    METHODS check_structure
      IMPORTING it_readings    TYPE tt_readings
      RETURNING VALUE(rv_rule) TYPE string.
    METHODS check_duration
      IMPORTING it_readings    TYPE tt_readings
      RETURNING VALUE(rv_rule) TYPE string.
    METHODS check_gap
      IMPORTING it_readings    TYPE tt_readings
      RETURNING VALUE(rv_rule) TYPE string.
    METHODS check_temperatures
      IMPORTING it_readings    TYPE tt_readings
      RETURNING VALUE(rv_rule) TYPE string.
    METHODS mean_tenths
      IMPORTING it_readings    TYPE tt_readings
      RETURNING VALUE(rv_mean) TYPE i.
ENDCLASS.


CLASS {{p}}cold_chain_check IMPLEMENTATION.
  METHOD constructor.
    ms_config = is_config.
  ENDMETHOD.

  METHOD check.
    DATA(lv_rule) = first_violation( it_readings ).
    IF lv_rule IS NOT INITIAL.
      RAISE EXCEPTION TYPE {{p}}cx_cold_chain
        EXPORTING
          iv_rule = lv_rule.
    ENDIF.
    rv_mean = mean_tenths( it_readings ).
  ENDMETHOD.

  METHOD first_violation.
    rv_rule = check_structure( it_readings ).
    IF rv_rule IS NOT INITIAL.
      RETURN.
    ENDIF.
    rv_rule = check_duration( it_readings ).
    IF rv_rule IS NOT INITIAL.
      RETURN.
    ENDIF.
    rv_rule = check_gap( it_readings ).
    IF rv_rule IS NOT INITIAL.
      RETURN.
    ENDIF.
    rv_rule = check_temperatures( it_readings ).
  ENDMETHOD.

  METHOD check_structure.
    IF lines( it_readings ) < 2.
      rv_rule = 'TOO_FEW'.
      RETURN.
    ENDIF.
    READ TABLE it_readings INDEX 1 INTO DATA(ls_first).
    IF ls_first-offset_min <> 0.
      rv_rule = 'NO_START'.
      RETURN.
    ENDIF.
    DATA(lv_previous) = ls_first-offset_min.
    LOOP AT it_readings FROM 2 INTO DATA(ls_reading).
      IF ls_reading-offset_min <= lv_previous.
        rv_rule = 'TIME_ORDER'.
        RETURN.
      ENDIF.
      lv_previous = ls_reading-offset_min.
    ENDLOOP.
  ENDMETHOD.

  METHOD check_duration.
    DATA lv_last TYPE i.
    LOOP AT it_readings INTO DATA(ls_reading).
      lv_last = ls_reading-offset_min.
    ENDLOOP.
    IF lv_last < ms_config-min_duration.
      rv_rule = 'TOO_SHORT'.
    ENDIF.
  ENDMETHOD.

  METHOD check_gap.
    DATA lv_previous TYPE i.
    LOOP AT it_readings INTO DATA(ls_reading).
      IF sy-tabix > 1 AND ls_reading-offset_min - lv_previous > ms_config-max_gap.
        rv_rule = 'GAP'.
        RETURN.
      ENDIF.
      lv_previous = ls_reading-offset_min.
    ENDLOOP.
  ENDMETHOD.

  METHOD check_temperatures.
    LOOP AT it_readings INTO DATA(ls_reading).
      IF ls_reading-temp_tenths > ms_config-max_tenths.
        rv_rule = 'TOO_HIGH'.
        RETURN.
      ENDIF.
      IF ls_reading-temp_tenths < ms_config-min_tenths.
        rv_rule = 'TOO_LOW'.
        RETURN.
      ENDIF.
    ENDLOOP.
  ENDMETHOD.

  METHOD mean_tenths.
    DATA lv_sum TYPE i.
    LOOP AT it_readings INTO DATA(ls_reading).
      lv_sum = lv_sum + ls_reading-temp_tenths.
    ENDLOOP.
    DATA(lv_count) = lines( it_readings ).
    IF lv_count = 0.
      rv_mean = 0.
      RETURN.
    ENDIF.
    DATA(lv_abs_sum) = lv_sum.
    IF lv_abs_sum < 0.
      lv_abs_sum = -1 / lv_abs_sum.
    ENDIF.
    rv_mean = lv_abs_sum DIV lv_count.
    IF lv_sum < 0.
      rv_mean = -1 * rv_mean.
    ENDIF.
  ENDMETHOD.
ENDCLASS.