decode static method

(int, List<int>) decode(String? hrp, String addr)

Decodes a Bech32-encoded SegWit address.

This method decodes a Bech32-encoded SegWit address, verifying its format, Human-Readable Part (HRP), witness version, and witness program.

• hrp: The expected Human-Readable Part (HRP) for the address.
• addr: The Bech32-encoded SegWit address to decode.

Returns a tuple containing the SegWit version (witness version) and the decoded witness program as a List.

Implementation

static (int, List<int>) decode(String? hrp, String addr) {
  final decoded = Bech32DecoderBase.decodeBech32(
    addr,
    SegwitBech32Const.separator,
    SegwitBech32Const.checksumStrLen,
    _verifyChecksum,
  );
  final hrpGot = decoded.$1;
  final data = decoded.$2;

  // Check HRP
  if (hrp != null && hrp != hrpGot) {
    throw Bech32Error(
      "Incorrect bech32 hrp.",
      details: {"expected": hrp, "hrp": hrpGot},
    );
  }

  // Convert back from base32 (remove witness version)
  final convData = Bech32BaseUtils.convertFromBase32(data.sublist(1));

  // Check data length
  if (convData.length < SegwitBech32Const.witnessProgMinByteLen ||
      convData.length > SegwitBech32Const.witnessProgMaxByteLen) {
    throw ArgumentException.invalidOperationArguments(
      "decode",
      reason: 'Invalid bech32 format.',
    );
  }

  // Check witness version
  final witVer = data[0];
  if (witVer > SegwitBech32Const.witnessVerMaxVal) {
    throw ArgumentException.invalidOperationArguments(
      "decode",
      reason: 'Invalid bech32 format.',
    );
  }

  if (witVer == 0 &&
      !SegwitBech32Const.witnessVerZeroDataByteLen.contains(
        convData.length,
      )) {
    throw ArgumentException.invalidOperationArguments(
      "decode",
      reason: 'Invalid bech32 format.',
    );
  }

  return (witVer, convData);
}