static List base64StringToBytes()

in lib/src/crypto.dart [118:170]

• 45 lines of code
• 15 McCabe index (conditional complexity)

  static List<int> base64StringToBytes(String input,
      [bool ignoreInvalidCharacters = true]) {
    int len = input.length;
    if (len == 0) {
      return const <int>[];
    }

    // Count '\r', '\n' and illegal characters, For illegal characters,
    // if [ignoreInvalidCharacters] is false, throw an exception.
    int extrasLen = 0;
    for (int i = 0; i < len; i++) {
      int c = _decodeTable[input.codeUnitAt(i)];
      if (c < 0) {
        extrasLen++;
        if (c == -2 && !ignoreInvalidCharacters) {
          throw FormatException('Invalid character: ${input[i]}');
        }
      }
    }

    if ((len - extrasLen) % 4 != 0) {
      throw FormatException('''Size of Base 64 characters in Input
          must be a multiple of 4. Input: $input''');
    }

    // Count pad characters, ignore illegal characters at the end.
    int padLength = 0;
    for (int i = len - 1; i >= 0; i--) {
      int currentCodeUnit = input.codeUnitAt(i);
      if (_decodeTable[currentCodeUnit] > 0) break;
      if (currentCodeUnit == PAD) padLength++;
    }
    int outputLen = (((len - extrasLen) * 6) >> 3) - padLength;
    List<int> out = List<int>.filled(outputLen, null);

    for (int i = 0, o = 0; o < outputLen;) {
      // Accumulate 4 valid 6 bit Base 64 characters into an int.
      int x = 0;
      for (int j = 4; j > 0;) {
        int c = _decodeTable[input.codeUnitAt(i++)];
        if (c >= 0) {
          x = ((x << 6) & 0xFFFFFF) | c;
          j--;
        }
      }
      out[o++] = x >> 16;
      if (o < outputLen) {
        out[o++] = (x >> 8) & 0xFF;
        if (o < outputLen) out[o++] = x & 0xFF;
      }
    }
    return out;
  }