cake_wallet/cw_bitcoin/lib/litecoin_wallet_addresses.dart

import 'dart:async';
import 'dart:typed_data';

import 'package:bech32/bech32.dart';
import 'package:bitcoin_base/bitcoin_base.dart';
import 'package:blockchain_utils/blockchain_utils.dart';
import 'package:cw_bitcoin/bitcoin_address_record.dart';
import 'package:cw_bitcoin/electrum_wallet.dart';
import 'package:cw_bitcoin/utils.dart';
import 'package:cw_bitcoin/electrum_wallet_addresses.dart';
import 'package:cw_core/wallet_info.dart';
import 'package:cw_mweb/cw_mweb.dart';
import 'package:flutter/foundation.dart';
import 'package:mobx/mobx.dart';

part 'litecoin_wallet_addresses.g.dart';

String encodeMwebAddress(List<int> scriptPubKey) {
  return bech32.encode(Bech32("ltcmweb1", scriptPubKey), 250);
}

class LitecoinWalletAddresses = LitecoinWalletAddressesBase with _$LitecoinWalletAddresses;

abstract class LitecoinWalletAddressesBase extends ElectrumWalletAddresses with Store {
  LitecoinWalletAddressesBase(
    WalletInfo walletInfo, {
    required super.mainHd,
    required super.sideHd,
    required super.network,
    required this.mwebHd,
    required this.mwebEnabled,
    super.initialAddresses,
    super.initialRegularAddressIndex,
    super.initialChangeAddressIndex,
  }) : super(walletInfo) {
    // start generating mweb addresses in the background:
    // initMwebAddresses();
  }

  final Bip32Slip10Secp256k1 mwebHd;
  bool mwebEnabled;
  int mwebTopUpIndex = 1000;
  List<String> mwebAddrs = [];
  static Timer? mwebTopUpTimer;

  List<int> get scanSecret => mwebHd.childKey(Bip32KeyIndex(0x80000000)).privateKey.privKey.raw;
  List<int> get spendPubkey =>
      mwebHd.childKey(Bip32KeyIndex(0x80000001)).publicKey.pubKey.compressed;

  @override
  Future<void> init() async {
    await super.init();
    initMwebAddresses();
  }

  Future<void> ensureMwebAddressUpToIndexExists(int index) async {
    Uint8List scan = Uint8List.fromList(scanSecret);
    Uint8List spend = Uint8List.fromList(spendPubkey);
    while (mwebAddrs.length <= (index + 1)) {
      final address = await CwMweb.address(scan, spend, mwebAddrs.length);
      mwebAddrs.add(address!);
    }
  }

  Future<void> generateNumAddresses(int num) async {
    Uint8List scan = Uint8List.fromList(scanSecret);
    Uint8List spend = Uint8List.fromList(spendPubkey);
    for (int i = 0; i < num; i++) {
      final address = await CwMweb.address(scan, spend, mwebAddrs.length);
      mwebAddrs.add(address!);
      await Future.delayed(Duration.zero);
    }
  }

  Future<void> initMwebAddresses() async {
    print("Initializing MWEB address timer!");
    Timer.periodic(const Duration(seconds: 2), (timer) async {
      if (super.allAddresses.length > 1000) {
        timer.cancel();
        return;
      }
      print("Generating MWEB addresses...");
      await generateNumAddresses(250);
      await Future.delayed(const Duration(milliseconds: 1500));

      if (mwebAddrs.length > 1000) {
        // convert mwebAddrs to BitcoinAddressRecords:
        List<BitcoinAddressRecord> mwebAddresses = mwebAddrs
            .asMap()
            .entries
            .map((e) => BitcoinAddressRecord(
                  e.value,
                  index: e.key,
                  type: SegwitAddresType.mweb,
                  network: network,
                ))
            .toList();
        // add them to the list of all addresses:
        addAddresses(mwebAddresses);
        print("MWEB addresses initialized ${mwebAddrs.length}");
        timer.cancel();
        return;
      }
    });
  }

  @override
  String getAddress({
    required int index,
    required Bip32Slip10Secp256k1 hd,
    BitcoinAddressType? addressType,
  }) {
    if (addressType == SegwitAddresType.mweb) {
      return hd == sideHd ? mwebAddrs[0] : mwebAddrs[index + 1];
    }
    return generateP2WPKHAddress(hd: hd, index: index, network: network);
  }

  @override
  Future<String> getAddressAsync({
    required int index,
    required Bip32Slip10Secp256k1 hd,
    BitcoinAddressType? addressType,
  }) async {
    if (addressType == SegwitAddresType.mweb) {
      await ensureMwebAddressUpToIndexExists(index);
    }
    return getAddress(index: index, hd: hd, addressType: addressType);
  }

  @action
  @override
  Future<String> getChangeAddress({List<BitcoinOutput>? outputs, UtxoDetails? utxoDetails}) async {
    // use regular change address on peg in, otherwise use mweb for change address:

    if (outputs != null && utxoDetails != null) {
      // check if this is a PEGIN:
      bool outputsToMweb = false;
      bool comesFromMweb = false;

      for (var i = 0; i < outputs.length; i++) {
        // TODO: probably not the best way to tell if this is an mweb address
        // (but it doesn't contain the "mweb" text at this stage)
        if (outputs[i].address.toAddress(network).length > 110) {
          outputsToMweb = true;
        }
      }
      utxoDetails.availableInputs.forEach((element) {
        if (element.address.contains("mweb")) {
          comesFromMweb = true;
        }
      });

      bool isPegIn = !comesFromMweb && outputsToMweb;
      if (isPegIn && mwebEnabled) {
        return super.getChangeAddress();
      }
    }

    if (mwebEnabled) {
      await ensureMwebAddressUpToIndexExists(1);
      return mwebAddrs[0];
    }

    return super.getChangeAddress();
  }
}