OOP_G01_Project_EENG4/src/backend/MoveHistory.java

package backend;

import java.util.ArrayList;
import java.util.List;

public class MoveHistory {
    private final List<MoveRecord> moveRecords;
    private final Board board;

    // Inner class to store a move along with board state (like en passant target)
    private static class MoveRecord {
        private final Move move;
        private final int enPassantTargetX;
        private final int enPassantTargetY;

        public MoveRecord(Move move, int enPassantTargetX, int enPassantTargetY) {
            this.move = move;
            this.enPassantTargetX = enPassantTargetX;
            this.enPassantTargetY = enPassantTargetY;
        }

        public Move getMove() {
            return move;
        }

        public int getEnPassantTargetX() {
            return enPassantTargetX;
        }

        public int getEnPassantTargetY() {
            return enPassantTargetY;
        }
    }

    public MoveHistory(Board board) {
        this.board = board;
        this.moveRecords = new ArrayList<>();
    }

    // Add a move to the history, capturing the board's state at this point
    public void addMove(Move move) {
        MoveRecord record = new MoveRecord(
            move,
            board.getEnPassantTargetX(),
            board.getEnPassantTargetY()
        );
        moveRecords.add(record);
        System.out.println("MoveHistory: Added move from (" + move.getFromX() + "," + move.getFromY() +
                           ") to (" + move.getToX() + "," + move.getToY() + ")");
    }

    // Clear the move history (e.g., when resetting the board)
    public void clear() {
        moveRecords.clear();
        System.out.println("MoveHistory: Cleared all moves");
    }

    // Undo the last move and update the board state
    public boolean undoLastMove() {
        if (moveRecords.isEmpty()) {
            System.out.println("MoveHistory: No moves to undo");
            return false;
        }

        MoveRecord lastRecord = moveRecords.remove(moveRecords.size() - 1);
        Move lastMove = lastRecord.getMove();
        System.out.println("MoveHistory: Undoing move from (" + lastMove.getFromX() + "," + lastMove.getFromY() +
                           ") to (" + lastMove.getToX() + "," + lastMove.getToY() + ")");

        // Restore the piece to its original position
        Piece pieceMoved = board.getPieceAt(lastMove.getToX(), lastMove.getToY());
        if (pieceMoved == null || pieceMoved.getType() != lastMove.getPieceMoved().getType() || pieceMoved.isWhite() != lastMove.getPieceMoved().isWhite()) {
            System.err.println("MoveHistory: Piece mismatch during undo at (" + lastMove.getToX() + "," + lastMove.getToY() + ")");
            return false;
        }
        pieceMoved.setPosition(lastMove.getFromX(), lastMove.getFromY());

        // Restore any captured piece (normal capture or en passant)
        Piece pieceCaptured = lastMove.getPieceCaptured();
        boolean wasEnPassantCapture = false;
        if (pieceCaptured != null) {
            // Check if this was an en passant capture
            if (lastMove.getToX() == lastRecord.getEnPassantTargetX() &&
                lastMove.getToY() == lastRecord.getEnPassantTargetY() &&
                lastMove.getPieceCaptured() == null) {
                // For en passant, the captured pawn is at (toX, fromY)
                int capturedPawnY = lastMove.getFromY();
                board.setPiece(pieceCaptured.isWhite(), pieceCaptured.getType(), lastMove.getToX(), capturedPawnY);
                System.out.println("MoveHistory: Restored en passant captured pawn at (" + lastMove.getToX() + "," + capturedPawnY + ")");
                wasEnPassantCapture = true;
            } else {
                // Normal capture: restore the captured piece at the destination
                board.setPiece(pieceCaptured.isWhite(), pieceCaptured.getType(), lastMove.getToX(), lastMove.getToY());
                System.out.println("MoveHistory: Restored captured piece at (" + lastMove.getToX() + "," + lastMove.getToY() + ")");
            }
        }

        // If this wasn't an en passant capture but the move captured a piece, remove the piece we just moved back
        if (!wasEnPassantCapture && pieceCaptured != null) {
            board.getPieces().removeIf(p -> p.getX() == lastMove.getToX() && p.getY() == lastMove.getToY() && p != pieceMoved);
        }

        // Restore the en passant target state
        board.enPassantTargetX = lastRecord.getEnPassantTargetX();
        board.enPassantTargetY = lastRecord.getEnPassantTargetY();
        System.out.println("MoveHistory: Restored en passant target to (" + board.enPassantTargetX + "," + board.enPassantTargetY + ")");

        // Update turn number and player turn
        board.turnNumber--;
        board.isTurnWhite = !board.isTurnWhite;

        // Clear selection and highlights
        board.selectedX = -1;
        board.selectedY = -1;
        board.clearHighlightedPositions();

        System.out.println("MoveHistory: After undo - Pieces: " + board.getPieces().size());
        for (Piece piece : board.getPieces()) {
            System.out.println("Piece at (" + piece.getX() + "," + piece.getY() + "): " + piece.getType() + ", isWhite=" + piece.isWhite());
        }
        return true;
    }
}