mchess-client/lib/chess_bloc/chess_bloc.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:mchess/chessapp/chess_board.dart';

import 'package:mchess/chessapp/chess_utils.dart';
import 'package:mchess/chessapp/chess_square.dart';

class ChessBloc extends Bloc<ChessEvent, ChessBoardState> {
  static final ChessBloc _instance = ChessBloc._internal();

  ChessBloc._internal() : super(ChessBoardState.init()) {
    on<PieceMoved>(moveHandler);
    on<PreCheckMove>(preCheckHandler);
  }

  factory ChessBloc.getInstance() {
    return ChessBloc();
  }

  factory ChessBloc() {
    return _instance;
  }

  FutureOr<void> moveHandler(
    PieceMoved event,
    Emitter<ChessBoardState> emit,
  ) {
    Map<ChessCoordinate, ChessPiece> newPosition = {};

    newPosition[event.endSquare] = state.position[event.startSquare]!;
    newPosition[event.startSquare] = const ChessPiece.none();

    print('emitting new state with position $newPosition');
    emit(ChessBoardState(
      state.flipped,
      ChessColor.black,
      newPosition,
    ));
  }

  FutureOr<bool> preCheckHandler(
    PreCheckMove event,
    Emitter<ChessBoardState> emit,
  ) {
    return false;
  }
}

abstract class ChessEvent {}

class PieceMoved extends ChessEvent {
  final ChessCoordinate startSquare;
  final ChessCoordinate endSquare;

  PieceMoved({required this.startSquare, required this.endSquare});
}

class PreCheckMove extends ChessEvent {}

class BoardFlippedEvent extends ChessEvent {}

class ChessBoardState {
  final bool flipped;
  final ChessColor turnColor;
  final Map<ChessCoordinate, ChessPiece> position;

  ChessBoardState._(this.flipped, this.turnColor, this.position);

  factory ChessBoardState(
    bool flipped,
    ChessColor turnColor,
    Map<ChessCoordinate, ChessPiece> position,
  ) {
    return ChessBoardState._(flipped, turnColor, position);
  }

  factory ChessBoardState.init() {
    bool flipped = false;
    ChessColor turnColor = ChessColor.white;
    Map<ChessCoordinate, ChessPiece> position = {};

    for (int row = 1; row <= 8; row++) {
      for (int col = 1; col <= 8; col++) {
        position[ChessCoordinate(row, col)] =
            ChessPiece(ChessPieceName.none, ChessColor.white);
        if (col == 1 && row == 4) {
          position[ChessCoordinate(col, row)] =
              ChessPiece(ChessPieceName.blackKing, ChessColor.black);
        }
      }
    }

    return ChessBoardState._(flipped, turnColor, position);
  }
}