mchess-client/lib/chess_bloc/chess_position.dart

import 'dart:developer';

import 'package:mchess/utils/chess_utils.dart';

typedef ChessMoveHistory = List<ChessMove>;
typedef ChessPositionType = Map<ChessCoordinate, ChessPiece>;

class ChessPosition {
  static ChessPosition _instance = ChessPosition._internal();
  static ChessMoveHistory history = ChessMoveHistory.empty(growable: true);
  final ChessPositionType position;

  ChessPosition({required this.position});

  factory ChessPosition._internal() {
    return ChessPosition(position: _getStartingPosition());
  }

  ChessPositionType get copyOfCurrentPosition => Map.from(position);

  ChessPositionType get currentPosition => position;
  ChessMove? get lastMove {
    if (history.isEmpty) return null;
    return history.last;
  }

  ChessPositionType fromPGNString(String pgn) {
    ChessPositionType pos = {};
    List<String> rowStrings;

    rowStrings = pgn.split('/');

    for (int row = 1; row <= 8; row++) {
      for (int col = 1; col <= 8; col++) {
        var piece = rowStrings.elementAt(row - 1)[col - 1];
        if (piece == '-') {
          continue;
        }
        pos[ChessCoordinate(col, row)] = pieceFromShortname[piece]!;
      }
    }

    return pos;
  }

  ChessPiece? getPieceAt(ChessCoordinate coordinate) {
    return position[ChessCoordinate(coordinate.column, coordinate.row)];
  }

  void logHistory(ChessMoveHistory hist) {
    for (var element in hist) {
      log('${element.from.toAlphabetical()} -> ${element.to.toAlphabetical()}');
    }
  }

  void logPosition(ChessPositionType p) {
    String logString = '';

    for (int row = 8; row > 0; row--) {
      for (int col = 1; col <= 8; col++) {
        var coord = ChessCoordinate(col, row);
        if (p.containsKey(coord)) {
          logString = '$logString ${p[coord]?.shortName}';
        } else {
          logString = '$logString .';
        }
      }
      logString = '$logString\n';
    }

    log(logString);
  }

  void recordMove(ChessCoordinate from, ChessCoordinate to) {
    position[to] = position[from] ?? const ChessPiece.none();
    position[from] = const ChessPiece.none();

    history.add(ChessMove(from: from, to: to));

    logPosition(position);

    logHistory(history);
  }

  void resetToStartingPosition() {
    history = ChessMoveHistory.empty(growable: true);
    _instance = ChessPosition(position: _getStartingPosition());
  }

  static ChessPosition getInstance() {
    return _instance;
  }

  static ChessPositionType _getStartingPosition() {
    ChessPositionType pos = {};

    for (int i = 1; i <= 8; i++) {
      pos[ChessCoordinate(i, 7)] =
          ChessPiece(ChessPieceClass.pawn, ChessColor.black);
      pos[ChessCoordinate(i, 2)] =
          ChessPiece(ChessPieceClass.pawn, ChessColor.white);
    }

    pos[ChessCoordinate(1, 8)] =
        ChessPiece(ChessPieceClass.rook, ChessColor.black);
    pos[ChessCoordinate(2, 8)] =
        ChessPiece(ChessPieceClass.knight, ChessColor.black);
    pos[ChessCoordinate(3, 8)] =
        ChessPiece(ChessPieceClass.bishop, ChessColor.black);
    pos[ChessCoordinate(4, 8)] =
        ChessPiece(ChessPieceClass.queen, ChessColor.black);
    pos[ChessCoordinate(5, 8)] =
        ChessPiece(ChessPieceClass.king, ChessColor.black);
    pos[ChessCoordinate(6, 8)] =
        ChessPiece(ChessPieceClass.bishop, ChessColor.black);
    pos[ChessCoordinate(7, 8)] =
        ChessPiece(ChessPieceClass.knight, ChessColor.black);
    pos[ChessCoordinate(8, 8)] =
        ChessPiece(ChessPieceClass.rook, ChessColor.black);

    pos[ChessCoordinate(1, 1)] =
        ChessPiece(ChessPieceClass.rook, ChessColor.white);
    pos[ChessCoordinate(2, 1)] =
        ChessPiece(ChessPieceClass.knight, ChessColor.white);
    pos[ChessCoordinate(3, 1)] =
        ChessPiece(ChessPieceClass.bishop, ChessColor.white);
    pos[ChessCoordinate(4, 1)] =
        ChessPiece(ChessPieceClass.queen, ChessColor.white);
    pos[ChessCoordinate(5, 1)] =
        ChessPiece(ChessPieceClass.king, ChessColor.white);
    pos[ChessCoordinate(6, 1)] =
        ChessPiece(ChessPieceClass.bishop, ChessColor.white);
    pos[ChessCoordinate(7, 1)] =
        ChessPiece(ChessPieceClass.knight, ChessColor.white);
    pos[ChessCoordinate(8, 1)] =
        ChessPiece(ChessPieceClass.rook, ChessColor.white);

    return pos;
  }
}