mchess-client/lib/chess_bloc/tap_bloc.dart

import 'dart:developer';

import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:mchess/chess_bloc/chess_bloc.dart';
import 'package:mchess/chess_bloc/chess_events.dart';
import 'package:mchess/chess_bloc/promotion_bloc.dart';
import 'package:mchess/utils/chess_utils.dart';

class TapBloc extends Bloc<TapEvent, TapState> {
  static final TapBloc _instance = TapBloc._internal();

  static TapBloc getInstance() {
    return _instance;
  }

  factory TapBloc() {
    return _instance;
  }

  TapBloc._internal() : super(TapState.init()) {
    on<SquareTappedEvent>(handleTap);
    on<CancelTapEvent>(cancelTap);
  }

  void handleTap(SquareTappedEvent event, Emitter<TapState> emit) {
    ChessCoordinate? firstTappedSquare, secondTappedSquare;
    ChessPiece? piece;

    if (ChessBloc.myColor != ChessBloc.turnColor) return;

    if (state.firstSquareTapped == null) {
      //first tap
      if (event.pieceOnSquare == null) return;
      if (event.pieceOnSquare != null &&
          ChessBloc.myColor != event.pieceOnSquare!.color) return;
      firstTappedSquare = event.tapped;
      piece = event.pieceOnSquare;
    } else {
      //second tap
      if (event.pieceOnSquare?.color == ChessBloc.myColor) {
        emit(TapState(
            firstSquareTapped: event.tapped,
            pieceOnFirstTappedSquare: event.pieceOnSquare,
            secondSquareTapped: null));
        return;
      }
      secondTappedSquare = event.tapped;
    }

    if (state.firstSquareTapped != null &&
        state.firstSquareTapped != event.tapped) {
      if (isPromotionMove(
        state.pieceOnFirstTappedSquare!.pieceClass,
        ChessBloc.myColor,
        event.tapped,
      )) {
        PromotionBloc().add(PawnMovedToPromotionField(
            move: ChessMove(from: state.firstSquareTapped!, to: event.tapped),
            colorMoved: ChessBloc.myColor));
        emit(TapState.init());
        return;
      } else {
        ChessBloc().add(OwnPieceMoved(
            startSquare: state.firstSquareTapped!, endSquare: event.tapped));
        emit(TapState.init());
        return;
      }
    }
    log("handleTap() in TapBloc is called");
    emit(TapState(
        firstSquareTapped: firstTappedSquare,
        pieceOnFirstTappedSquare: piece,
        secondSquareTapped: secondTappedSquare));
  }

  void cancelTap(CancelTapEvent event, Emitter<TapState> emit) {
    emit(TapState.init());
  }
}

abstract class TapEvent {}

class SquareTappedEvent extends TapEvent {
  ChessCoordinate tapped;
  ChessPiece? pieceOnSquare;

  SquareTappedEvent({required this.tapped, required this.pieceOnSquare});
}

class CancelTapEvent extends TapEvent {}

class TapState {
  ChessCoordinate? firstSquareTapped;
  ChessPiece? pieceOnFirstTappedSquare;

  ChessCoordinate? secondSquareTapped;

  TapState(
      {required this.firstSquareTapped,
      required this.pieceOnFirstTappedSquare,
      required this.secondSquareTapped});

  factory TapState.init() {
    return TapState(
        firstSquareTapped: null,
        pieceOnFirstTappedSquare: null,
        secondSquareTapped: null);
  }
}