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omnichess/lib/functions/_partials/legal_moves_black.dart

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part of "../legal_moves.dart";
class _LegalMovesBlack {
_LegalMovesBlack._();
static Stream<(String, Position)> _getLegalMoves(Position position) => _getValidOrCheckedMoves(position).where(((String, Position) move) => !_isBlackChecked(move.$2));
static Stream<(String, Position)> _getValidOrCheckedMoves(Position position) async* {
for (int i = 0; i < 64; i++) {
switch (position.board[i]) {
case Piece.emptySquare:
case Piece.whitePawn:
case Piece.whiteKnight:
case Piece.whiteBishop:
case Piece.whiteRook:
case Piece.whiteQueen:
case Piece.whiteKing:
break;
case Piece.blackPawn:
yield* _getBlackPawnMoves(position, i);
break;
case Piece.blackKnight:
yield* _getBlackKnightMoves(position, i);
break;
case Piece.blackBishop:
yield* _getBlackBishopMoves(position, i);
break;
case Piece.blackRook:
yield* _getBlackRookMoves(position, i);
break;
case Piece.blackQueen:
yield* _getBlackBishopMoves(position, i);
yield* _getBlackRookMoves(position, i);
break;
case Piece.blackKing:
yield* _getBlackKingMoves(position, i);
break;
}
}
}
static Stream<(String, Position)> _getBlackPawnMoves(Position position, int i) async* {
int j = i+8;
if (Piece.emptySquare == position.board[j]) { // pawn forward
if (i > 47) {
final String squareFrom = Position.squareIndexToString(i);
final String squareTo = Position.squareIndexToString(j);
yield ("$squareFrom${squareTo}q", Position.from(position)..playMoveIndices(i, j, "q"));
yield ("$squareFrom${squareTo}r", Position.from(position)..playMoveIndices(i, j, "r"));
yield ("$squareFrom${squareTo}b", Position.from(position)..playMoveIndices(i, j, "b"));
yield ("$squareFrom${squareTo}k", Position.from(position)..playMoveIndices(i, j, "k"));
} else {
final String squareFrom = Position.squareIndexToString(i);
yield ("$squareFrom${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
j = i+16;
if (i < 16 && Piece.emptySquare == position.board[j]) { // pawn more forward
yield ("$squareFrom${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
}
j = i+7;
if (i % 8 > 0 && (j == position.enPassantTargetSquare || Piece.isWhite(position.board[j]))) { // pawn takes left
if (i > 47) {
final String squareFrom = Position.squareIndexToString(i);
final String squareTo = Position.squareIndexToString(j);
yield ("$squareFrom${squareTo}q", Position.from(position)..playMoveIndices(i, j, "q"));
yield ("$squareFrom${squareTo}r", Position.from(position)..playMoveIndices(i, j, "r"));
yield ("$squareFrom${squareTo}b", Position.from(position)..playMoveIndices(i, j, "b"));
yield ("$squareFrom${squareTo}k", Position.from(position)..playMoveIndices(i, j, "k"));
} else {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
j = i+9;
if (i % 8 < 7 && (j == position.enPassantTargetSquare || Piece.isWhite(position.board[j]))) { // pawn takes right
if (i > 47) {
final String squareFrom = Position.squareIndexToString(i);
final String squareTo = Position.squareIndexToString(j);
yield ("$squareFrom${squareTo}q", Position.from(position)..playMoveIndices(i, j, "q"));
yield ("$squareFrom${squareTo}r", Position.from(position)..playMoveIndices(i, j, "r"));
yield ("$squareFrom${squareTo}b", Position.from(position)..playMoveIndices(i, j, "b"));
yield ("$squareFrom${squareTo}k", Position.from(position)..playMoveIndices(i, j, "k"));
} else {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
}
static Stream<(String, Position)> _getBlackKnightMoves(Position position, int i) async* {
final bool canGoUp2 = i > 15;
final bool canGoUp1 = i > 7;
final bool canGoDown1 = i < 56;
final bool canGoDown2 = i < 48;
final int column = i % 8;
final bool canGoLeft2 = column > 1;
final bool canGoLeft1 = column > 0;
final bool canGoRight1 = column < 7;
final bool canGoRight2 = column < 6;
if (canGoUp1) {
if (canGoLeft2 && !Piece.isBlack(position.board[i-10])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i-10)}", Position.from(position)..playMoveIndices(i, i-10));
}
if (canGoRight2 && !Piece.isBlack(position.board[i-6])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i-6)}", Position.from(position)..playMoveIndices(i, i-6));
}
if (canGoUp2) {
if (canGoLeft1 && !Piece.isBlack(position.board[i-17])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i-17)}", Position.from(position)..playMoveIndices(i, i-17));
}
if (canGoRight1 && !Piece.isBlack(position.board[i-15])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i-15)}", Position.from(position)..playMoveIndices(i, i-15));
}
}
}
if (canGoDown1) {
if (canGoLeft2 && !Piece.isBlack(position.board[i+6])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i+6)}", Position.from(position)..playMoveIndices(i, i+6));
}
if (canGoRight2 && !Piece.isBlack(position.board[i+10])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i+10)}", Position.from(position)..playMoveIndices(i, i+10));
}
if (canGoDown2) {
if (canGoLeft1 && !Piece.isBlack(position.board[i+15])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i+15)}", Position.from(position)..playMoveIndices(i, i+15));
}
if (canGoRight1 && !Piece.isBlack(position.board[i+17])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(i+17)}", Position.from(position)..playMoveIndices(i, i+17));
}
}
}
}
static Stream<(String, Position)> _getBlackBishopMoves(Position position, int i) async* {
final int column = i % 8;
// up left
bool hasEncounteredPiece = false;
int k = column-1;
int j = i-9;
while (!hasEncounteredPiece && k >= 0 && j >= 0) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
k--;
j-=9;
}
// up right
hasEncounteredPiece = false;
k = column+1;
j = i-7;
while (!hasEncounteredPiece && k < 8 && j >= 0) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
k++;
j-=7;
}
// down left
hasEncounteredPiece = false;
k = column-1;
j = i+7;
while (!hasEncounteredPiece && k >= 0 && j < 64) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
k--;
j+=7;
}
// down right
hasEncounteredPiece = false;
k = column+1;
j = i+9;
while (!hasEncounteredPiece && k < 8 && j < 64) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
k++;
j+=9;
}
}
static Stream<(String, Position)> _getBlackRookMoves(Position position, int i) async* {
final int column = i % 8;
// up
bool hasEncounteredPiece = false;
int j = i-8;
while (!hasEncounteredPiece && j > 0) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
j-=8;
}
// down
hasEncounteredPiece = false;
j = i+8;
while (!hasEncounteredPiece && j < 64) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
j+=8;
}
// left
hasEncounteredPiece = false;
int k = column-1;
j = i-1;
while (!hasEncounteredPiece && k >= 0) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
j-=1;
k-=1;
}
// right
hasEncounteredPiece = false;
k = column+1;
j = i+1;
while (!hasEncounteredPiece && k < 8) {
if (Piece.emptySquare == position.board[j]) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
} else {
hasEncounteredPiece = true;
if (Piece.isWhite(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
j+=1;
k+=1;
}
}
static Stream<(String, Position)> _getBlackKingMoves(Position position, int i) async* {
int j = i-8;
if (j >= 0 && !Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
j = i+8;
if (j < 64 && !Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
if (i % 8 > 0) {
j = i-1;
if (!Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
j = i-9;
if (j >= 0 && !Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
j = i+7;
if (j < 64 && !Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
if (i % 8 < 7) {
j = i+1;
if (!Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
j = i-7;
if (j >= 0 && !Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
j = i+9;
if (j < 64 && !Piece.isBlack(position.board[j])) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
if(!_isWhiteAttacking(position, i)) {
j = i-2;
if (
position.canBlackCastleQueenside &&
Piece.emptySquare == position.board[i-1] &&
Piece.emptySquare == position.board[i-2] &&
!_isWhiteAttacking(position, i-1)
) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
j = i+2;
if (
position.canBlackCastleKingside &&
Piece.emptySquare == position.board[i+1] &&
Piece.emptySquare == position.board[i+2] &&
!_isWhiteAttacking(position, i+1)
) {
yield ("${Position.squareIndexToString(i)}${Position.squareIndexToString(j)}", Position.from(position)..playMoveIndices(i, j));
}
}
}
static int _getBlackKingSquare(Position position) {
for (int i = 0; i < 64; i++) {
if (position.board[i] == Piece.blackKing) {
return i;
}
}
throw KingNotFoundException();
}
static bool _isBlackChecked(Position position) => _isWhiteAttacking(position, _getBlackKingSquare(position));
static bool _isWhiteAttacking(Position position, int square) {
if (_isWhitePawnAttacking(position, square)) {
return true;
}
if (_isWhiteKnightAttacking(position, square)) {
return true;
}
if (_isWhiteBishopOrQueenAttacking(position, square)) {
return true;
}
if (_isWhiteRookOrQueenAttacking(position, square)) {
return true;
}
if (_isWhiteKingAttacking(position, square)) {
return true;
}
return false;
}
static bool _isWhitePawnAttacking(Position position, int square) {
if (square < 8) {
return false;
}
final int column = square % 8;
if (column > 0 && Piece.whitePawn == position.board[square + 7]) {
return true;
}
if (column < 7 && Piece.whitePawn == position.board[square + 9]) {
return true;
}
return false;
}
static bool _isWhiteKnightAttacking(Position position, int square) {
final bool canGoUp2 = square > 15;
final bool canGoUp1 = square > 7;
final bool canGoDown1 = square < 56;
final bool canGoDown2 = square < 48;
final int column = square % 8;
final bool canGoLeft2 = column > 1;
final bool canGoLeft1 = column > 0;
final bool canGoRight1 = column < 7;
final bool canGoRight2 = column < 6;
if (canGoUp1) {
if (canGoLeft2 && Piece.whiteKnight == position.board[square-10]) {
return true;
}
if (canGoRight2 && Piece.whiteKnight == position.board[square-6]) {
return true;
}
if (canGoUp2) {
if (canGoLeft1 && Piece.whiteKnight == position.board[square-17]) {
return true;
}
if (canGoRight1 && Piece.whiteKnight == position.board[square-15]) {
return true;
}
}
}
if (canGoDown1) {
if (canGoLeft2 && Piece.whiteKnight == position.board[square+6]) {
return true;
}
if (canGoRight2 && Piece.whiteKnight == position.board[square+10]) {
return true;
}
if (canGoDown2) {
if (canGoLeft1 && Piece.whiteKnight == position.board[square+15]) {
return true;
}
if (canGoRight1 && Piece.whiteKnight == position.board[square+17]) {
return true;
}
}
}
return false;
}
static bool _isWhiteBishopOrQueenAttacking(Position position, int square) {
final int column = square % 8;
// up left
bool hasEncounteredPiece = false;
int k = column-1;
int j = square-9;
while (!hasEncounteredPiece && k >= 0 && j >= 0) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteBishop || Piece.whiteQueen) {
return true;
}
}
k--;
j-=9;
}
// up right
hasEncounteredPiece = false;
k = column+1;
j = square-7;
while (!hasEncounteredPiece && k < 8 && j >= 0) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteBishop || Piece.whiteQueen) {
return true;
}
}
k++;
j-=7;
}
// down left
hasEncounteredPiece = false;
k = column-1;
j = square+7;
while (!hasEncounteredPiece && k >= 0 && j < 64) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteBishop || Piece.whiteQueen) {
return true;
}
}
k--;
j+=7;
}
// down right
hasEncounteredPiece = false;
k = column+1;
j = square+9;
while (!hasEncounteredPiece && k < 8 && j < 64) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteBishop || Piece.whiteQueen) {
return true;
}
}
k++;
j+=9;
}
return false;
}
static bool _isWhiteRookOrQueenAttacking(Position position, int square) {
final int column = square % 8;
// up
bool hasEncounteredPiece = false;
int j = square-8;
while (!hasEncounteredPiece && j > 0) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteRook || Piece.whiteQueen) {
return true;
}
}
j-=8;
}
// down
hasEncounteredPiece = false;
j = square + 8;
while (!hasEncounteredPiece && j < 64) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteRook || Piece.whiteQueen) {
return true;
}
}
j+=8;
}
// left
hasEncounteredPiece = false;
j = square - 1;
int k = column - 1;
while (!hasEncounteredPiece && k > 0) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteRook || Piece.whiteQueen) {
return true;
}
}
j--;
k--;
}
// right
hasEncounteredPiece = false;
j = square + 1;
k = column + 1;
while (!hasEncounteredPiece && k < 8) {
final int piece = position.board[j];
if (Piece.emptySquare != piece) {
hasEncounteredPiece = true;
if (piece case Piece.whiteRook || Piece.whiteQueen) {
return true;
}
}
j++;
k++;
}
return false;
}
static bool _isWhiteKingAttacking(Position position, int square) {
if (square > 7 && Piece.whiteKing == position.board[square - 8]) {
return true;
}
if (square < 56 && Piece.whiteKing == position.board[square + 8]) {
return true;
}
if (square % 8 > 0) {
if (Piece.whiteKing == position.board[square - 1]) {
return true;
}
if (square > 7 && Piece.whiteKing == position.board[square - 9]) {
return true;
}
if (square < 56 && Piece.whiteKing == position.board[square + 7]) {
return true;
}
}
if (square % 8 < 7) {
if (Piece.whiteKing == position.board[square + 1]) {
return true;
}
if (square > 7 && Piece.whiteKing == position.board[square - 7]) {
return true;
}
if (square < 56 && Piece.whiteKing == position.board[square + 9]) {
return true;
}
}
return false;
}
}
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