mchess-client/lib/utils/chess_utils.dart

import 'package:flutter/material.dart';
import 'package:flutter_svg/svg.dart';
import 'package:mchess/api/move.dart';
import 'package:mchess/api/websocket_message.dart';
import 'package:quiver/core.dart';

import '../chess_bloc/chess_position.dart';

enum ChessPieceClass {
  none,
  pawn,
  bishop,
  knight,
  rook,
  queen,
  king,
}

class ChessPieceAssetKey {
  final ChessPieceClass pieceClass;
  final ChessColor color;

  ChessPieceAssetKey({required this.pieceClass, required this.color});

  @override
  bool operator ==(Object other) {
    return (other is ChessPieceAssetKey &&
        (pieceClass == other.pieceClass) &&
        (color == other.color));
  }

  @override
  int get hashCode {
    return hash2(pieceClass, color);
  }
}

enum ChessColor {
  black,
  white;

  static ChessColor fromApiColor(ApiColor color) {
    if (color == ApiColor.black) {
      return black;
    } else {
      return white;
    }
  }

  ChessColor getOpposite() {
    if (name == 'black') {
      return white;
    } else {
      return black;
    }
  }
}

Map<ChessPieceAssetKey, String> chessPiecesAssets = {
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.pawn,
    color: ChessColor.white,
  ): 'assets/pieces/white/pawn.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.bishop,
    color: ChessColor.white,
  ): 'assets/pieces/white/bishop.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.knight,
    color: ChessColor.white,
  ): 'assets/pieces/white/knight.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.rook,
    color: ChessColor.white,
  ): 'assets/pieces/white/rook.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.queen,
    color: ChessColor.white,
  ): 'assets/pieces/white/queen.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.king,
    color: ChessColor.white,
  ): 'assets/pieces/white/king.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.pawn,
    color: ChessColor.black,
  ): 'assets/pieces/black/pawn.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.bishop,
    color: ChessColor.black,
  ): 'assets/pieces/black/bishop.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.knight,
    color: ChessColor.black,
  ): 'assets/pieces/black/knight.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.rook,
    color: ChessColor.black,
  ): 'assets/pieces/black/rook.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.queen,
    color: ChessColor.black,
  ): 'assets/pieces/black/queen.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.king,
    color: ChessColor.black,
  ): 'assets/pieces/black/king.svg',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.none,
    color: ChessColor.black,
  ): 'assets/empty.svg',
};

Map<ChessPieceAssetKey, String> chessPiecesShortName = {
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.pawn,
    color: ChessColor.white,
  ): 'P',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.bishop,
    color: ChessColor.white,
  ): 'B',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.knight,
    color: ChessColor.white,
  ): 'N',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.rook,
    color: ChessColor.white,
  ): 'R',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.queen,
    color: ChessColor.white,
  ): 'Q',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.king,
    color: ChessColor.white,
  ): 'K',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.pawn,
    color: ChessColor.black,
  ): 'p',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.bishop,
    color: ChessColor.black,
  ): 'b',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.knight,
    color: ChessColor.black,
  ): 'n',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.rook,
    color: ChessColor.black,
  ): 'r',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.queen,
    color: ChessColor.black,
  ): 'q',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.king,
    color: ChessColor.black,
  ): 'k',
  ChessPieceAssetKey(
    pieceClass: ChessPieceClass.none,
    color: ChessColor.black,
  ): '-',
};

class ChessCoordinate {
  final int column;
  final int row;

  ChessCoordinate(this.column, this.row);

  factory ChessCoordinate.fromString(String coordString) {
    var column = int.parse(coordString[0]);
    var row = int.parse(coordString[1]);

    return ChessCoordinate(column, row);
  }

  factory ChessCoordinate.fromApiCoordinate(ApiCoordinate apiCoordinate) {
    return ChessCoordinate(apiCoordinate.col, apiCoordinate.row);
  }

  ApiCoordinate toApiCoordinate() {
    return ApiCoordinate(col: column, row: row);
  }

  ChessCoordinate.copyFrom(ChessCoordinate original)
      : column = original.column,
        row = original.row;

  static String columnIntToColumnString(int col) {
    String colStr;

    colStr = String.fromCharCode(col + 96);

    return colStr;
  }

  static int columnStringToColumnInt(String col) {
    int colInt;
    colInt = col.codeUnitAt(0) - 96;
    return colInt;
  }

  @override
  String toString() {
    String rowStr = row.toString();
    String colStr = column.toString();

    return '$colStr$rowStr';
  }

  String toAlphabetical() {
    Map<int, String> columnMap = {
      1: "a",
      2: "b",
      3: "c",
      4: "d",
      5: "e",
      6: "f",
      7: "g",
      8: "h"
    };
    String rowStr = row.toString();
    String colStr = columnMap[column]!;

    return '$colStr$rowStr';
  }

  @override
  operator ==(other) {
    return other is ChessCoordinate &&
        other.column == column &&
        other.row == row;
  }

  @override
  int get hashCode {
    return hash2(column, row);
  }
}

class ChessPiece extends StatelessWidget {
  final ChessColor color;
  final ChessPieceClass pieceClass;
  final String shortName;
  final Widget? pieceImage;

  const ChessPiece._(
      this.pieceClass, this.color, this.pieceImage, this.shortName);

  factory ChessPiece(ChessPieceClass pieceClass, ChessColor color) {
    Widget? pieceImage;
    String pieceAssetUrl = chessPiecesAssets[
        ChessPieceAssetKey(pieceClass: pieceClass, color: color)]!;
    String shortName = chessPiecesShortName[
        ChessPieceAssetKey(pieceClass: pieceClass, color: color)]!;

    pieceImage = SvgPicture.asset(pieceAssetUrl);
    return ChessPiece._(pieceClass, color, pieceImage, shortName);
  }

  const ChessPiece.none({super.key})
      : pieceClass = ChessPieceClass.none,
        color = ChessColor.white,
        pieceImage = null,
        shortName = "-";

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      child: pieceImage,
    );
  }
}

class ChessMove {
  ChessCoordinate from;
  ChessCoordinate to;

  ChessMove({required this.from, required this.to});

  factory ChessMove.fromApiMove(ApiMove apiMove) {
    final start = ChessCoordinate.fromApiCoordinate(apiMove.startSquare);
    final end = ChessCoordinate.fromApiCoordinate(apiMove.endSquare);

    return ChessMove(from: start, to: end);
  }

  ApiMove toApiMove() {
    var toSquare = to.toApiCoordinate();
    var fromSquare = from.toApiCoordinate();
    return ApiMove(
        startSquare: fromSquare, endSquare: toSquare, promotionToPiece: null);
  }

  @override
  operator ==(other) {
    return other is ChessMove && other.from == from && other.to == to;
  }

  @override
  int get hashCode {
    return hash2(from, to);
  }

  bool wasEnPassant() {
    var pieceMoved = ChessPosition.getInstance().getPieceAt(from);
    var pieceAtEndSquare = ChessPosition.getInstance().getPieceAt(to);
    if (pieceMoved != null &&
        pieceMoved.pieceClass == ChessPieceClass.pawn &&
        pieceAtEndSquare == null &&
        from.column != to.column) {
      return true;
    }
    return false;
  }

  bool wasCastling() {
    var pieceMoved = ChessPosition.getInstance().getPieceAt(from);
    if (pieceMoved != null && pieceMoved.pieceClass == ChessPieceClass.king) {
      var colDiff = (from.column - to.column).abs();
      if (colDiff == 2) {
        return true;
      }
    }
    return false;
  }
}

class PieceDragged {
  ChessCoordinate fromSquare;
  ChessCoordinate toSquare;
  ChessPiece? movedPiece;

  PieceDragged(this.fromSquare, this.toSquare, this.movedPiece);
}