works well for pawns (need to add others pieces)

src/backend/Board.java

@@ -9,6 +9,13 @@ public class Board {
     private ArrayList<Piece> pieces;
     private int turnNumber;
     private boolean turnWhite;
+    private Integer selectedX = null;
+    private Integer selectedY = null;
+    private ArrayList<int[]> highlightedSquares = new ArrayList<>();
+    private ArrayList<Move> moveHistory = new ArrayList<>();
+
+
+
 
 	/*public Board(int colNum, int lineNum) {
 		 this.width = colNum;
@@ -119,37 +126,210 @@ public class Board {
 	}
 
 	public void userTouch(int x, int y) {
-		//TODO
+	    Piece clickedPiece = getPieceAt(x, y);
 
+	    // No selection yet
+	    if (selectedX == null || selectedY == null) {
+	        if (clickedPiece != null && clickedPiece.isWhite() == turnWhite) {
+	            selectedX = x;
+	            selectedY = y;
+	            highlightedSquares = computeLegalMoves(clickedPiece);
+	        }
+	        return;
+	    }
+
+	    // Clicked the same square again → unselect
+	    if (selectedX == x && selectedY == y) {
+	        selectedX = null;
+	        selectedY = null;
+	        highlightedSquares.clear();
+	        return;
+	    }
+
+	    // Otherwise, try to move
+	    Piece selectedPiece = getPieceAt(selectedX, selectedY);
+	    if (selectedPiece == null) {
+	        // Somehow no piece at selected position (safety check)
+	        selectedX = null;
+	        selectedY = null;
+	        highlightedSquares.clear();
+	        return;
+	    }
+
+	    // Check if clicked destination is valid
+	    boolean validMove = false;
+	    for (int[] pos : highlightedSquares) {
+	        if (pos[0] == x && pos[1] == y) {
+	            validMove = true;
+	            break;
+	        }
+	    }
+
+	    if (!validMove) {
+	        // Invalid destination → reset
+	        selectedX = null;
+	        selectedY = null;
+	        highlightedSquares.clear();
+	        return;
+	    }
+
+	    // Move is valid → capture if needed
+	    Piece target = getPieceAt(x, y);
+
+	    // Log the move for undo
+	    Move move = new Move(
+	        selectedPiece.getType(),
+	        selectedPiece.isWhite(),
+	        selectedX, selectedY,
+	        x, y,
+	        target // may be null
+	    );
+	    moveHistory.add(move);
+
+	    // Remove captured piece if any
+	    if (target != null) {
+	        pieces.remove(target);
+	    }
+
+	    // Remove the original piece
+	    pieces.remove(selectedPiece);
+
+	    // Add new piece at destination
+	    setPiece(selectedPiece.isWhite(), selectedPiece.getType(), x, y);
+
+	    // Update turn
+	    turnNumber++;
+	    turnWhite = !turnWhite;
+
+	    // Clear selection and highlights
+	    selectedX = null;
+	    selectedY = null;
+	    highlightedSquares.clear();
 	}
 
 	public boolean isSelected(int x, int y) {
-		//TODO
+	    return selectedX != null && selectedY != null && selectedX == x && selectedY == y;
-		return false;
 	}
 
+	
 	/* saving-loading feature :*/
 
 	public String[] toFileRep() {
-		//TODO
+	    String[] fileRep = new String[height + 1]; // 8 rows + 1 for turn
-		return null;
+	    String[][] grid = new String[height][width];
+
+	    // Fill with empty squares
+	    for (int y = 0; y < height; y++) {
+	        for (int x = 0; x < width; x++) {
+	            grid[y][x] = "--";
+	        }
+	    }
+
+	    // Fill with pieces
+	    for (Piece piece : pieces) {
+	        String color = piece.isWhite() ? "W" : "B";
+	        String type = piece.getType().toString().substring(0, 1); // P, R, N, B, Q, K
+	        grid[piece.getY()][piece.getX()] = color + type;
+	    }
+
+	    // Convert grid to CSV-like strings
+	    for (int y = 0; y < height; y++) {
+	        StringBuilder row = new StringBuilder();
+	        for (int x = 0; x < width; x++) {
+	            row.append(grid[y][x]);
+	            if (x < width - 1) {
+	                row.append(",");
+	            }
+	        }
+	        fileRep[y] = row.toString();
+	    }
+
+	    // Last line = turn
+	    fileRep[height] = turnWhite ? "W" : "B";
+
+	    return fileRep;
 	}
 
+
 	public Board(String[] array) {
-		//TODO
+	    this.width = 8;
+	    this.height = 8;
+	    this.pieces = new ArrayList<>();
+	    this.turnNumber = 0;
+	    this.turnWhite = array[8].equals("W");
 
+	    for (int y = 0; y < height; y++) {
+	        String[] row = array[y].split(",");
+	        for (int x = 0; x < width; x++) {
+	            String code = row[x];
+	            if (!code.equals("--")) {
+	                boolean isWhite = code.charAt(0) == 'W';
+	                char typeChar = code.charAt(1);
+	                PieceType type = null;
+
+	                switch (typeChar) {
+	                    case 'P':
+	                        type = PieceType.Pawn;
+	                        break;
+	                    case 'R':
+	                        type = PieceType.Rook;
+	                        break;
+	                    case 'N':
+	                        type = PieceType.Knight;
+	                        break;
+	                    case 'B':
+	                        type = PieceType.Bishop;
+	                        break;
+	                    case 'Q':
+	                        type = PieceType.Queen;
+	                        break;
+	                    case 'K':
+	                        type = PieceType.King;
+	                        break;
+	                }
+
+	                if (type != null) {
+	                    setPiece(isWhite, type, x, y);
+	                }
+	            }
+	        }
+	    }
 	}
 
+	
 	/* The following methods require more work ! */
 
 	public boolean isHighlighted(int x, int y) {
-		//TODO
+	    for (int[] pos : highlightedSquares) {
-		return false;
+	        if (pos[0] == x && pos[1] == y) {
+	            return true;
+	        }
+	    }
+	    return false;
 	}
   
 	public void undoLastMove() {
-		//TODO
+	    if (moveHistory.isEmpty()) return;
 
+	    Move lastMove = moveHistory.remove(moveHistory.size() - 1);
+
+	    // Remove piece from destination
+	    Piece movedPiece = getPieceAt(lastMove.getToX(), lastMove.getToY());
+	    if (movedPiece != null) {
+	        pieces.remove(movedPiece);
+	    }
+
+	    // Restore moved piece to original location
+	    setPiece(lastMove.isWhite(), lastMove.getType(), lastMove.getFromX(), lastMove.getFromY());
+
+	    // Restore captured piece if there was one
+	    if (lastMove.getCapturedPiece() != null) {
+	        Piece cap = lastMove.getCapturedPiece();
+	        setPiece(cap.isWhite(), cap.getType(), cap.getX(), cap.getY());
+	    }
+
+	    turnNumber--;
+	    turnWhite = !turnWhite;
 	}
 
 	public Board(Board board) {
@@ -162,4 +342,51 @@ public class Board {
 
 	}
 
+
+private Piece getPieceAt(int x, int y) {
+    for (Piece p : pieces) {
+        if (p.getX() == x && p.getY() == y) {
+            return p;
+        }
+    }
+    return null;
 }
+
+private boolean isEmpty(int x, int y) {
+    return getPieceAt(x, y) == null;
+}
+
+private boolean isEnemy(int x, int y, boolean isWhite) {
+    Piece p = getPieceAt(x, y);
+    return p != null && p.isWhite() != isWhite;
+}
+
+private ArrayList<int[]> computeLegalMoves(Piece piece) {
+    ArrayList<int[]> moves = new ArrayList<>();
+    int x = piece.getX();
+    int y = piece.getY();
+    PieceType type = piece.getType();
+
+    if (type == PieceType.Pawn) {
+        int dir = piece.isWhite() ? 1 : -1;
+        int nextY = y + dir;
+
+        // Move forward if square is empty
+        if (isEmpty(x, nextY)) {
+            moves.add(new int[]{x, nextY});
+        }
+
+        // Diagonal capture
+        if (isEnemy(x - 1, nextY, piece.isWhite())) {
+            moves.add(new int[]{x - 1, nextY});
+        }
+        if (isEnemy(x + 1, nextY, piece.isWhite())) {
+            moves.add(new int[]{x + 1, nextY});
+        }
+    }
+
+    return moves;
+}
+
+}
+

src/backend/Move.java

@@ -1,5 +1,27 @@
 package backend;
 
 public class Move {
+    private int fromX, fromY;
+    private int toX, toY;
+    private boolean isWhite;
+    private PieceType type;
+    private Piece capturedPiece;
 
+    public Move(PieceType type, boolean isWhite, int fromX, int fromY, int toX, int toY, Piece capturedPiece) {
+        this.fromX = fromX;
+        this.fromY = fromY;
+        this.toX = toX;
+        this.toY = toY;
+        this.isWhite = isWhite;
+        this.type = type;
+        this.capturedPiece = capturedPiece;
+    }
+
+    public int getFromX() { return fromX; }
+    public int getFromY() { return fromY; }
+    public int getToX() { return toX; }
+    public int getToY() { return toY; }
+    public boolean isWhite() { return isWhite; }
+    public PieceType getType() { return type; }
+    public Piece getCapturedPiece() { return capturedPiece; }
 }