import java.util.*;

// We are making this an *immutable* class.  The state that an object has when constructed is its state permanently.
// Instead of making changes to objects we create new ones (with attemptMove() and the constructor).

public class GameState {
	Square[] boardSquares; //Tracks the game board as a 1D array of Square objects (effectively 12 x 12) with 2 layers of sentinel squares all around.
	boolean isWhitesTurn;  //Knows whose turn it is

	public GameState() {
		//Set turn to white
		isWhitesTurn = true;

		//Initialize squares with legal starting position.
		boardSquares = new Square[] {
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.ROOK, true), new Square(Square.KNIGHT, true), new Square(Square.BISHOP, true), new Square(Square.KING, true), new Square(Square.QUEEN, true), new Square(Square.BISHOP, true), new Square(Square.KNIGHT, true), new Square(Square.ROOK, true), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),  //white
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), //white pawns

			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),

			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), //white pawns
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.ROOK, false), new Square(Square.KNIGHT, false), new Square(Square.BISHOP, false), new Square(Square.KING, false), new Square(Square.QUEEN, false), new Square(Square.BISHOP, false), new Square(Square.KNIGHT, false), new Square(Square.ROOK, false), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),  //black
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
			new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
		};

	}

	// zero-based index for col and row.  Note that -1 and -2 are valid indices into the array, just OUT_OF_BOUNDS.
	public Square getSquare(int col, int row) {
		return boardSquares[12*2 + 2 + col + row * 12];
	}

	public GameState getStateAfterMove(Move m) {
		//See if it is legal.  If not, return null.
		//Create a new object based on this one, update the board state accordingly.
		return null;
	}

	public ArrayList<Move> getAllPossibleMoves() {
		ArrayList<Move> moves = new ArrayList<Move>();

		//Loop through all squares
		for(int index = 0; index < boardSquares.length; index++) {
			int type = boardSquares[index].getType();
			if (type == Square.OUT_OF_BOUNDS) continue;
			if (type == Square.EMPTY) continue;

			//For each square, find all possible places that piece can move to.
			if (type == Square.KING) moves.addAll(findAllMovesFor(index, new int[] {1,-1,12,-12,13,-13,11,-11}, false));
			if (type == Square.QUEEN) moves.addAll(findAllMovesFor(index, new int[] {1,-1,12,-12,13,-13,11,-11}, true));
			if (type == Square.BISHOP) moves.addAll(findAllMovesFor(index, new int[] {13,-13,11,-11}, true));
			if (type == Square.ROOK) moves.addAll(findAllMovesFor(index, new int[] {1,-1,12,-12}, true));
			if (type == Square.KNIGHT) moves.addAll(findAllMovesFor(index, new int[] {10,14,23,25,-10,-14,-23,-25}, false));
		}

		return moves;
	}

	private ArrayList<Move> findAllMovesFor(int index, int[] directions, boolean canMoveMultipleSquares) {
		ArrayList<Move> moves = new ArrayList<Move>();
		//loop through the directions, see if they work - return the resulting arraylist.
		for(int dir : directions) {
			int destIndex = index + dir;
			int type = boardSquares[destIndex].getType();
			if (boardSquares[index].isWhite() != isWhitesTurn) continue; //don't move other person's pieces!

			if (type == Square.OUT_OF_BOUNDS) continue;
			if (type == Square.EMPTY || boardSquares[destIndex].isWhite() != isWhitesTurn) {
				moves.add(new Move(index, destIndex));
			}

		}
		return moves;
	}

	// returns something like "checkmate", "stalemate", etc.
	public String getFeedback() {
		return null;
	}
}