From e50739c8342bebc7651b077d8330b94bf86b53ad Mon Sep 17 00:00:00 2001
From: jefei <jefei@DESKTOP-UN89UPJ>
Date: Sat, 17 May 2025 14:10:28 +0200
Subject: [PATCH] Check and Checkmate Detection but not fully optimized

---
 src/backend/Board.java                    | 92 +++++++++++++++++++++++
 src/backend/Game.java                     |  3 +
 src/windowInterface/JPanelChessBoard.java | 17 +++++
 src/windowInterface/MyInterface.java      |  1 +
 4 files changed, 113 insertions(+)

diff --git a/src/backend/Board.java b/src/backend/Board.java
index 648d84a..60b4055 100644
--- a/src/backend/Board.java
+++ b/src/backend/Board.java
@@ -4,6 +4,9 @@ import java.util.ArrayList;
 import java.util.Stack;
 
 public class Board {
+	private int checkedKingX = -1;
+	private int checkedKingY = -1;
+	private boolean checkmateFlag = false;
 private Piece lastDoubleStepPawn = null;
 private int width;
 private int height;
@@ -23,6 +26,9 @@ private boolean whiteQueensideRookMoved = false;
 private boolean blackKingsideRookMoved = false;
 private boolean blackQueensideRookMoved = false;
 
+public int getCheckedKingX() { return checkedKingX; }
+public int getCheckedKingY() { return checkedKingY; }
+public boolean isCheckmateFlag() { return checkmateFlag; }
 
 public String[] toFileRep() {
     String[] lines = new String[height + 1];
@@ -309,9 +315,30 @@ public void userTouch(int x, int y) {
         turnWhite = !turnWhite;
         hasSelection = false;
         System.out.println(this);
+     // 🧠 CHECK & CHECKMATE logic
+        checkedKingX = -1;
+        checkedKingY = -1;
+        checkmateFlag = false;
+
+        boolean opponentInCheck = isInCheck(turnWhite);
+        if (opponentInCheck) {
+            Piece king = getKing(turnWhite);
+            if (king != null) {
+                checkedKingX = king.getX();
+                checkedKingY = king.getY();
+                System.out.println("⚠️ " + (turnWhite ? "White" : "Black") + " king is in check!");
+            }
+        }
+
+        if (isCheckmate(turnWhite)) {
+            checkmateFlag = true;
+            System.out.println("♟️ " + (!turnWhite ? "White" : "Black") + " wins by checkmate!");
+        }
+
     }
 }
 
+
 public boolean isSelected(int x, int y) {
 	// return true if the exact square is currently picked up
 	return hasSelection && selectedX == x && selectedY == y;
@@ -651,4 +678,69 @@ public void selectPiece(int x, int y) {
     selectedX = x;
     selectedY = y;
 }
+public boolean isInCheck(boolean white) {
+    // Step 1: Locate the king
+    Piece king = null;
+    for (Piece p : Pieces) {
+        if (p.getType() == PieceType.King && p.isWhite() == white) {
+            king = p;
+            break;
+        }
+    }
+    if (king == null) return false;
+
+    int kingX = king.getX();
+    int kingY = king.getY();
+
+    // Step 2: Check all enemy pieces to see if they can hit king
+    for (Piece p : Pieces) {
+        if (p.isWhite() != white) {
+            Board temp = new Board(this);
+            temp.selectPiece(p.getX(), p.getY());
+            temp.hasSelection = true;
+
+            for (int tx = 0; tx < width; tx++) {
+                for (int ty = 0; ty < height; ty++) {
+                    if (temp.isHighlighted(tx, ty) && tx == kingX && ty == kingY) {
+                        return true;
+                    }
+                }
+            }
+        }
+    }
+
+    return false;
 }
+
+
+public boolean isCheckmate(boolean white) {
+    if (!isInCheck(white)) return false;
+
+    for (Piece p : Pieces) {
+        if (p.isWhite() == white) {
+            Board copy = new Board(this);
+            copy.selectPiece(p.getX(), p.getY());
+            for (int x = 0; x < width; x++) {
+                for (int y = 0; y < height; y++) {
+                    if (copy.isHighlighted(x, y)) {
+                        Board trial = new Board(this);
+                        trial.selectPiece(p.getX(), p.getY());
+                        trial.userTouch(x, y);
+                        if (!trial.isInCheck(white)) {
+                            return false;
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return true;
+}
+public Piece getKing(boolean white) {
+    for (Piece p : Pieces) {
+        if (p.getType() == PieceType.King && p.isWhite() == white) return p;
+    }
+    return null;
+}
+
+}
\ No newline at end of file
diff --git a/src/backend/Game.java b/src/backend/Game.java
index 41ca541..89e8621 100644
--- a/src/backend/Game.java
+++ b/src/backend/Game.java
@@ -114,5 +114,8 @@ public class Game extends Thread {
 	public void toggleAI(boolean isWhite) {
 		this.activationAIFlags[isWhite?1:0] = !this.activationAIFlags[isWhite?1:0];
 	}
+	public Board getBoard() {
+	    return this.board;
+	}
 
 }
diff --git a/src/windowInterface/JPanelChessBoard.java b/src/windowInterface/JPanelChessBoard.java
index 1368e37..2e6e376 100644
--- a/src/windowInterface/JPanelChessBoard.java
+++ b/src/windowInterface/JPanelChessBoard.java
@@ -112,6 +112,23 @@ public class JPanelChessBoard extends JPanel {
 					if(isHighlight) {
 						g.setColor(Color.yellow);
 					}
+					// 🔴 Highlight the checked/checkmated king
+					if (myGame != null) {
+					    backend.Board board = myGame.getBoard();
+					    int checkX = board.getCheckedKingX();
+					    int checkY = board.getCheckedKingY();
+
+					    if (checkX != -1 && checkY != -1) {
+					        g.setColor(board.isCheckmateFlag() ? Color.RED : Color.ORANGE);
+					        g.fillRect(
+					            Math.round(checkX * cellWidth),
+					            Math.round(checkY * cellHeight),
+					            Math.round(cellWidth),
+					            Math.round(cellHeight)
+					        );
+					    }
+					}
+
 					if((x+y)%2==1 || isSelect || isHighlight) {
 						g.fillRect(
 								Math.round(x*cellWidth),
diff --git a/src/windowInterface/MyInterface.java b/src/windowInterface/MyInterface.java
index 513842a..6328f0a 100644
--- a/src/windowInterface/MyInterface.java
+++ b/src/windowInterface/MyInterface.java
@@ -162,6 +162,7 @@ public class MyInterface extends JFrame {
 	public void clicButtonStart() {
 		this.instantiateSimu();
 		game.setDefaultSetup();
+	    
 	}
 	
 	public void clickButtonAdder() {