nationalIT function

String nationalIT(String bban, BbanStructure structure)

Implementation

String nationalIT(String bban, BbanStructure structure) {
  const List<int> even = [
    0,
    1,
    2,
    3,
    4,
    5,
    6,
    7,
    8,
    9,
    10,
    11,
    12,
    13,
    14,
    15,
    16,
    17,
    18,
    19,
    20,
    21,
    22,
    23,
    24,
    25
  ];
  const List<int> odd = [
    1,
    0,
    5,
    7,
    9,
    13,
    15,
    17,
    19,
    21,
    2,
    4,
    18,
    20,
    11,
    3,
    6,
    8,
    12,
    14,
    16,
    10,
    22,
    25,
    24,
    23
  ];
  final int V0 = "0".codeUnitAt(0);
  final int V9 = "9".codeUnitAt(0);
  final int VA = "A".codeUnitAt(0);
  final List<int> listValues = [
    PartType.BANK_CODE,
    PartType.BRANCH_CODE,
    PartType.ACCOUNT_NUMBER
  ]
      .map((p) => structure.extractValueMust(bban, p))
      .join("")
      .split("")
      .map((v) => v.toUpperCase().codeUnitAt(0))
      .map((v) => v - (V0 <= v && v <= V9 ? V0 : VA))
      .toList();

  int value = 0;

  for (int i = 0; i < listValues.length; ++i) {
    value += (i % 2 == 0 ? odd[listValues[i]] : even[listValues[i]]);
  }

  value %= 26;

  return String.fromCharCode(VA + value);
}