CLASS {{p}}iban_validator DEFINITION PUBLIC FINAL CREATE PUBLIC.
  PUBLIC SECTION.
    INTERFACES {{p}}if_iban_check.

  PRIVATE SECTION.
    TYPES:
      BEGIN OF ty_country,
        code   TYPE c LENGTH 2,
        length TYPE i,
      END OF ty_country,
      tt_country TYPE HASHED TABLE OF ty_country WITH UNIQUE KEY code.

    METHODS normalize
      IMPORTING iv_iban        TYPE string
      RETURNING VALUE(rv_iban) TYPE string.
    METHODS has_valid_format
      IMPORTING iv_iban         TYPE string
      RETURNING VALUE(rv_valid) TYPE abap_bool.
    METHODS country_lengths
      RETURNING VALUE(rt_country) TYPE tt_country.
    METHODS remainder_97
      IMPORTING iv_iban       TYPE string
      RETURNING VALUE(rv_mod) TYPE i.
ENDCLASS.


CLASS {{p}}iban_validator IMPLEMENTATION.
  METHOD {{p}}if_iban_check~check.
    DATA(lv_iban) = normalize( iv_iban ).
    IF lv_iban IS INITIAL.
      rv_reason = {{p}}if_iban_check=>c_reason-empty.
      RETURN.
    ENDIF.
    IF has_valid_format( lv_iban ) = abap_false.
      rv_reason = {{p}}if_iban_check=>c_reason-chars.
      RETURN.
    ENDIF.
    DATA(lt_country) = country_lengths( ).
    ASSIGN lt_country[ code = substring( val = lv_iban len = 2 ) ] TO FIELD-SYMBOL(<ls_country>).
    IF sy-subrc <> 0.
      rv_reason = {{p}}if_iban_check=>c_reason-country.
      RETURN.
    ENDIF.
    IF strlen( lv_iban ) <> <ls_country>-length.
      rv_reason = {{p}}if_iban_check=>c_reason-length.
      RETURN.
    ENDIF.
    IF remainder_97( lv_iban ) <> 1.
      rv_reason = {{p}}if_iban_check=>c_reason-checksum.
      RETURN.
    ENDIF.
    rv_reason = {{p}}if_iban_check=>c_reason-ok.
  ENDMETHOD.

  METHOD normalize.
    rv_iban = to_upper( replace( val = iv_iban sub = ` ` with = `` occ = 0 ) ).
  ENDMETHOD.

  METHOD has_valid_format.
    rv_valid = xsdbool( matches( val = iv_iban pcre = `^[A-Z]{2}[0-9]{2}[A-Z0-9]*$` ) ).
  ENDMETHOD.

  METHOD country_lengths.
    rt_country = VALUE #( ( code = 'DE' length = 22 )
                          ( code = 'GB' length = 22 )
                          ( code = 'TR' length = 26 )
                          ( code = 'FR' length = 27 )
                          ( code = 'NL' length = 18 )
                          ( code = 'AT' length = 20 )
                          ( code = 'CH' length = 21 ) ).
  ENDMETHOD.

  METHOD remainder_97.
    DATA(lv_moved) = substring( val = iv_iban off = 4 ) && substring( val = iv_iban len = 4 ).
    DO strlen( lv_moved ) TIMES.
      DATA(lv_char) = substring( val = lv_moved off = sy-index - 1 len = 1 ).
      IF lv_char CO '0123456789'.
        rv_mod = ( rv_mod * 10 + CONV i( lv_char ) ) MOD 97.
      ELSE.
        rv_mod = ( rv_mod * 100 + find( val = sy-abcde sub = lv_char ) + 10 ) MOD 97.
      ENDIF.
    ENDDO.
  ENDMETHOD.
ENDCLASS.