add hungry ai

app/src/main/java/chess/SwingMain.java

@@ -1,6 +1,7 @@
 package chess;
 
 import chess.ai.DumbAI;
+import chess.ai.HungryAI;
 import chess.controller.CommandExecutor;
 import chess.controller.commands.NewGameCommand;
 import chess.controller.event.GameAdaptator;
@@ -20,7 +21,7 @@ public class SwingMain {
         DumbAI ai = new DumbAI(commandExecutor, Color.Black);
         commandExecutor.addListener(ai);
 
-        DumbAI ai2 = new DumbAI(commandExecutor, Color.White);
+        HungryAI ai2 = new HungryAI(commandExecutor, Color.White);
         commandExecutor.addListener(ai2);
 
         commandExecutor.addListener(new GameAdaptator(){

app/src/main/java/chess/ai/HungryAI.java

@@ -0,0 +1,61 @@
+package chess.ai;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+
+import chess.controller.CommandExecutor;
+import chess.controller.commands.MoveCommand;
+import chess.controller.commands.PromoteCommand;
+import chess.controller.commands.PromoteCommand.PromoteType;
+import chess.model.Color;
+import chess.model.Coordinate;
+import chess.model.Move;
+import chess.model.Piece;
+
+public class HungryAI extends AI {
+
+	private final PieceCost pieceCost;
+	private final Random random;
+
+	public HungryAI(CommandExecutor commandExecutor, Color color) {
+		super(commandExecutor, color);
+		this.pieceCost = new PieceCost(color);
+		this.random = new Random();
+	}
+
+	private int getMoveCost(Move move) {
+		Piece piece = pieceAt(move.getDeadPieceCoords());
+		return pieceCost.getCost(piece);
+	}
+
+	private List<Move> getBestMoves() {
+		List<Move> moves = getAllowedMoves();
+		List<Move> bestMoves = new ArrayList<>();
+		int bestCost = 0;
+		for (Move move : moves) {
+			int moveCost = getMoveCost(move);
+			if (moveCost == bestCost) {
+				bestMoves.add(move);
+			} else if (moveCost > bestCost) {
+				bestMoves.clear();
+				bestMoves.add(move);
+				bestCost = moveCost;
+			}
+		}
+		return bestMoves;
+	}
+
+	@Override
+	protected void play() {
+		List<Move> bestMoves = getBestMoves();
+		int randomMove = this.random.nextInt(bestMoves.size());
+		this.commandExecutor.executeCommand(new MoveCommand(bestMoves.get(randomMove)));
+	}
+
+	@Override
+	protected void promote(Coordinate pawnCoords) {
+		sendCommand(new PromoteCommand(PromoteType.Queen));
+	}
+
+}

app/src/main/java/chess/ai/PieceCost.java

@@ -0,0 +1,60 @@
+package chess.ai;
+
+import chess.model.Color;
+import chess.model.Piece;
+import chess.model.PieceVisitor;
+import chess.model.pieces.Bishop;
+import chess.model.pieces.King;
+import chess.model.pieces.Knight;
+import chess.model.pieces.Pawn;
+import chess.model.pieces.Queen;
+import chess.model.pieces.Rook;
+
+public class PieceCost implements PieceVisitor<Integer> {
+
+	private final Color player;
+
+	public PieceCost(Color color) {
+		this.player = color;
+	}
+
+	public int getCost(Piece piece) {
+		if (piece == null)
+			return 0;
+		int cost = visit(piece);
+		if (piece.getColor() == player)
+			cost = -cost;
+		return cost;
+	}
+
+	@Override
+	public Integer visitPiece(Bishop bishop) {
+		return 3;
+	}
+
+	@Override
+	public Integer visitPiece(King king) {
+		return 90;
+	}
+
+	@Override
+	public Integer visitPiece(Knight knight) {
+		return 3;
+	}
+
+	@Override
+	public Integer visitPiece(Pawn pawn) {
+		return 1;
+	}
+
+	@Override
+	public Integer visitPiece(Queen queen) {
+		return 9;
+	}
+
+	@Override
+	public Integer visitPiece(Rook rook) {
+		return 5;
+	}
+
+}