cake_wallet/cw_mweb/lib/cw_mweb.dart

import 'dart:async';
import 'dart:convert';
import 'dart:developer';
import 'dart:io';
import 'dart:typed_data';

import 'package:grpc/grpc.dart';
import 'package:path_provider/path_provider.dart';
import 'cw_mweb_platform_interface.dart';
import 'mwebd.pbgrpc.dart';

class CwMweb {
  static RpcClient? _rpcClient;
  static ClientChannel? _clientChannel;
  static int? _port;
  static const TIMEOUT_DURATION = Duration(seconds: 5);
  static Timer? logTimer;

  static void readFileWithTimer(String filePath) {
    final file = File(filePath);
    int lastLength = 0;

    logTimer?.cancel();
    logTimer = Timer.periodic(const Duration(seconds: 1), (timer) async {
      try {
        final currentLength = await file.length();

        if (currentLength != lastLength) {
          final fileStream = file.openRead(lastLength, currentLength);
          final newLines = await fileStream.transform(utf8.decoder).join();
          lastLength = currentLength;
          log(newLines);
        }
      } on GrpcError catch (e) {
        log('Caught grpc error: ${e.message}');
      } catch (e) {
        log('The mwebd debug log probably is not initialized yet.');
      }
    });
  }

  static Future<void> _initializeClient() async {
    print("_initializeClient() called!");
    final appDir = await getApplicationSupportDirectory();
    const ltcNodeUri = "ltc-electrum.cakewallet.com:9333";

    String debugLogPath = "${appDir.path}/logs/debug.log";
    readFileWithTimer(debugLogPath);

    _port = await CwMwebPlatform.instance.start(appDir.path, ltcNodeUri);
    if (_port == null || _port == 0) {
      throw Exception("Failed to start server");
    }
    log("Attempting to connect to server on port: $_port");

    // wait for the server to finish starting up before we try to connect to it:
    await Future.delayed(const Duration(seconds: 8));

    _clientChannel = ClientChannel('127.0.0.1', port: _port!, channelShutdownHandler: () {
      _rpcClient = null;
      log("Channel is shutting down!");
    },
        options: const ChannelOptions(
          credentials: ChannelCredentials.insecure(),
          keepAlive: ClientKeepAliveOptions(permitWithoutCalls: true),
        ));
    _rpcClient = RpcClient(_clientChannel!);
  }

  static Future<RpcClient> stub({int maxRetries = 3}) async {
    for (int i = 0; i < maxRetries; i++) {
      try {
        if (_rpcClient == null) {
          await _initializeClient();
        }
        final status = await _rpcClient!
            .status(StatusRequest(), options: CallOptions(timeout: TIMEOUT_DURATION));
        if (status.blockTime == 0) {
          throw Exception("blockTime shouldn't be 0! (this connection is likely broken)");
        }
        return _rpcClient!;
      } on GrpcError catch (e) {
        log("Attempt $i failed: $e");
        log('Caught grpc error: ${e.message}');
        _rpcClient = null;
        // necessary if the database isn't open:
        await stop();
        await Future.delayed(const Duration(seconds: 3));
      } catch (e) {
        log("Attempt $i failed: $e");
        _rpcClient = null;
        await stop();
        await Future.delayed(const Duration(seconds: 3));
      }
    }
    throw Exception("Failed to connect after $maxRetries attempts");
  }

  static Future<void> stop() async {
    try {
      await CwMwebPlatform.instance.stop();
      await cleanup();
    } on GrpcError catch (e) {
      log('Caught grpc error: ${e.message}');
    } catch (e) {
      log("Error stopping server: $e");
    }
  }

  static Future<String?> address(Uint8List scanSecret, Uint8List spendPub, int index) async {
    try {
      return (await CwMwebPlatform.instance.addresses(scanSecret, spendPub, index, index + 1))
          ?.split(',')
          .first;
    } on GrpcError catch (e) {
      log('Caught grpc error: ${e.message}');
    } catch (e) {
      log("Error getting address: $e");
    }
    return null;
  }

  static Future<List<String>?> addresses(
      Uint8List scanSecret, Uint8List spendPub, int fromIndex, int toIndex) async {
    try {
      return (await CwMwebPlatform.instance.addresses(scanSecret, spendPub, fromIndex, toIndex))
          ?.split(',');
    } on GrpcError catch (e) {
      log('Caught grpc error: ${e.message}');
    } catch (e) {
      log("Error getting addresses: $e");
    }
    return null;
  }

  static Future<void> cleanup() async {
    try {
      await _clientChannel?.terminate();
    } catch (_) {}
    _rpcClient = null;
    _clientChannel = null;
    _port = null;
  }

  // wrappers that handle the connection issues:
  static Future<SpentResponse> spent(SpentRequest request) async {
    log("mweb.spent() called");
    try {
      _rpcClient = await stub();
      return await _rpcClient!.spent(request, options: CallOptions(timeout: TIMEOUT_DURATION));
    } on GrpcError catch (e) {
      log('Caught grpc error: ${e.message}');
    } catch (e) {
      log("Error getting spent: $e");
    }
    return SpentResponse();
  }

  static Future<StatusResponse> status(StatusRequest request) async {
    log("mweb.status() called");
    try {
      _rpcClient = await stub();
      return await _rpcClient!.status(request, options: CallOptions(timeout: TIMEOUT_DURATION));
    } on GrpcError catch (e) {
      log('Caught grpc error: ${e.message}');
    } catch (e) {
      log("Error getting status: $e");
    }
    return StatusResponse();
  }

  static Future<CreateResponse> create(CreateRequest request) async {
    log("mweb.create() called");
    try {
      _rpcClient = await stub();
      return await _rpcClient!.create(request, options: CallOptions(timeout: TIMEOUT_DURATION));
    } on GrpcError catch (e) {
      log('Caught grpc error: ${e.message}');
    } catch (e) {
      log("Error getting create: $e");
    }
    return CreateResponse();
  }

  static Future<ResponseStream<Utxo>?> utxos(UtxosRequest request) async {
    log("mweb.utxos() called");
    try {
      _rpcClient = await stub();
      final resp = _rpcClient!
          .utxos(request, options: CallOptions(timeout: const Duration(days: 1000 * 365)));
      log("got utxo stream");
      return resp;
    } on GrpcError catch (e) {
      log('Caught grpc error: ${e.message}');
    } catch (e) {
      log("Error getting utxos: $e");
    }
    return null;
  }
}