part 2, push 1

src/backend/Move.java

@@ -40,4 +40,173 @@ public class Move {
     public Piece getPieceCaptured() {
         return pieceCaptured;
     }
+
+    // Static method to calculate all valid moves for a piece
+    public static String[] calculateValidMoves(Board board, Piece piece) {
+        String[] validMoves = new String[32]; // Allocate space for up to 32 moves
+        int[] moveCount = new int[1]; // Use an array to simulate a mutable counter
+        moveCount[0] = 0;
+
+        int x = piece.getX();
+        int y = piece.getY();
+        switch (piece.getType()) {
+            case Pawn:
+                calculatePawnMoves(board, piece, x, y, validMoves, moveCount);
+                break;
+            case Rook:
+                calculateRookMoves(board, piece, x, y, validMoves, moveCount);
+                break;
+            case Knight:
+                calculateKnightMoves(board, piece, x, y, validMoves, moveCount);
+                break;
+            case Bishop:
+                calculateBishopMoves(board, piece, x, y, validMoves, moveCount);
+                break;
+            case Queen:
+                calculateQueenMoves(board, piece, x, y, validMoves, moveCount);
+                break;
+            case King:
+                calculateKingMoves(board, piece, x, y, validMoves, moveCount);
+                break;
+        }
+
+        // Trim the array to the actual number of moves
+        String[] result = new String[moveCount[0]];
+        for (int i = 0; i < moveCount[0]; i++) {
+            result[i] = validMoves[i];
+        }
+        return result;
+    }
+
+    private static void calculatePawnMoves(Board board, Piece piece, int x, int y, String[] validMoves, int[] moveCount) {
+        int direction = piece.isWhite() ? -1 : 1; // White pawns move up, black pawns move down
+        int startRow = piece.isWhite() ? 6 : 1; // Starting row for double move
+
+        // Move forward one square
+        if (isValidPosition(board, x, y + direction) && getPieceAt(board, x, y + direction) == null) {
+            addMoveIfNotDuplicate(x, y + direction, validMoves, moveCount);
+            // Move forward two squares from starting position
+            if (y == startRow && getPieceAt(board, x, y + 2 * direction) == null) {
+                addMoveIfNotDuplicate(x, y + 2 * direction, validMoves, moveCount);
+            }
+        }
+
+        // Capture diagonally
+        if (isValidPosition(board, x - 1, y + direction)) {
+            Piece target = getPieceAt(board, x - 1, y + direction);
+            if (target != null && target.isWhite() != piece.isWhite()) {
+                addMoveIfNotDuplicate(x - 1, y + direction, validMoves, moveCount);
+            }
+        }
+        if (isValidPosition(board, x + 1, y + direction)) {
+            Piece target = getPieceAt(board, x + 1, y + direction);
+            if (target != null && target.isWhite() != piece.isWhite()) {
+                addMoveIfNotDuplicate(x + 1, y + direction, validMoves, moveCount);
+            }
+        }
+    }
+
+    private static void calculateRookMoves(Board board, Piece piece, int x, int y, String[] validMoves, int[] moveCount) {
+        // Horizontal: left
+        for (int i = x - 1; i >= 0; i--) {
+            if (!addMoveIfValid(board, piece, i, y, validMoves, moveCount)) break;
+        }
+        // Horizontal: right
+        for (int i = x + 1; i < board.getWidth(); i++) {
+            if (!addMoveIfValid(board, piece, i, y, validMoves, moveCount)) break;
+        }
+        // Vertical: up
+        for (int j = y - 1; j >= 0; j--) {
+            if (!addMoveIfValid(board, piece, x, j, validMoves, moveCount)) break;
+        }
+        // Vertical: down
+        for (int j = y + 1; j < board.getHeight(); j++) {
+            if (!addMoveIfValid(board, piece, x, j, validMoves, moveCount)) break;
+        }
+    }
+
+    private static void calculateKnightMoves(Board board, Piece piece, int x, int y, String[] validMoves, int[] moveCount) {
+        int[][] knightMoves = {
+            {-2, -1}, {-2, 1}, {-1, -2}, {-1, 2},
+            {1, -2}, {1, 2}, {2, -1}, {2, 1}
+        };
+        for (int i = 0; i < knightMoves.length; i++) {
+            int newX = x + knightMoves[i][0];
+            int newY = y + knightMoves[i][1];
+            addMoveIfValid(board, piece, newX, newY, validMoves, moveCount);
+        }
+    }
+
+    private static void calculateBishopMoves(Board board, Piece piece, int x, int y, String[] validMoves, int[] moveCount) {
+        // Diagonal: up-left
+        for (int i = 1; x - i >= 0 && y - i >= 0; i++) {
+            if (!addMoveIfValid(board, piece, x - i, y - i, validMoves, moveCount)) break;
+        }
+        // Diagonal: up-right
+        for (int i = 1; x + i < board.getWidth() && y - i >= 0; i++) {
+            if (!addMoveIfValid(board, piece, x + i, y - i, validMoves, moveCount)) break;
+        }
+        // Diagonal: down-left
+        for (int i = 1; x - i >= 0 && y + i < board.getHeight(); i++) {
+            if (!addMoveIfValid(board, piece, x - i, y + i, validMoves, moveCount)) break;
+        }
+        // Diagonal: down-right
+        for (int i = 1; x + i < board.getWidth() && y + i < board.getHeight(); i++) {
+            if (!addMoveIfValid(board, piece, x + i, y + i, validMoves, moveCount)) break;
+        }
+    }
+
+    private static void calculateQueenMoves(Board board, Piece piece, int x, int y, String[] validMoves, int[] moveCount) {
+        // Queen moves like a rook + bishop
+        calculateRookMoves(board, piece, x, y, validMoves, moveCount);
+        calculateBishopMoves(board, piece, x, y, validMoves, moveCount);
+    }
+
+    private static void calculateKingMoves(Board board, Piece piece, int x, int y, String[] validMoves, int[] moveCount) {
+        for (int dx = -1; dx <= 1; dx++) {
+            for (int dy = -1; dy <= 1; dy++) {
+                if (dx == 0 && dy == 0) continue;
+                int newX = x + dx;
+                int newY = y + dy;
+                addMoveIfValid(board, piece, newX, newY, validMoves, moveCount);
+            }
+        }
+    }
+
+    private static boolean addMoveIfValid(Board board, Piece piece, int x, int y, String[] validMoves, int[] moveCount) {
+        if (!isValidPosition(board, x, y)) return false;
+        Piece target = getPieceAt(board, x, y);
+        if (target == null || target.isWhite() != piece.isWhite()) {
+            addMoveIfNotDuplicate(x, y, validMoves, moveCount);
+            return target == null; // Continue if the square is empty, stop if we hit a piece
+        }
+        return false; // Stop if we hit a piece of the same color
+    }
+
+    private static void addMoveIfNotDuplicate(int x, int y, String[] validMoves, int[] moveCount) {
+        if (moveCount[0] >= validMoves.length) return; // Prevent array overflow
+        String position = x + "," + y;
+        // Check for duplicates
+        for (int i = 0; i < moveCount[0]; i++) {
+            if (validMoves[i] != null && validMoves[i].equals(position)) {
+                return; // Position already exists
+            }
+        }
+        validMoves[moveCount[0]] = position;
+        moveCount[0]++;
+    }
+
+    private static boolean isValidPosition(Board board, int x, int y) {
+        return x >= 0 && x < board.getWidth() && y >= 0 && y < board.getHeight();
+    }
+
+    private static Piece getPieceAt(Board board, int x, int y) {
+        Piece[] pieces = board.getPieces().toArray(new Piece[0]);
+        for (int i = 0; i < pieces.length; i++) {
+            if (pieces[i].getX() == x && pieces[i].getY() == y) {
+                return pieces[i];
+            }
+        }
+        return null;
+    }
 }