import java.util.*;

public class Position
{
   public Square square[][] = new Square[9][9];   //for convenience
   
   public Vector whitePieces = new Vector(), blackPieces = new Vector(), myPieces, enemyPieces;
   public Stack moveStack = new Stack();
	//private Stack capturedPieces = new Stack();
   private String turn = null; //"white"/"black"
	public boolean checkmate = false;
	public boolean stalemate = false;

   public Position()			    //default - initial position
	{
		int i,j;
		//create 64 new squares
		for (i = 1; i <= 8; i++) for (j = 1; j <= 8; j++) square[i][j] = new Square(i,j); 
		//squares receive their pieces
      Piece wk = new Piece("white","king"), bk = new Piece("black","king");
      wk.putOnSquare(square[5][1]); bk.putOnSquare(square[5][8]);
      Piece wqn = new Piece("white","queen"), bqn = new Piece("black","queen");
      wqn.putOnSquare(square[4][1]); bqn.putOnSquare(square[4][8]);
      Piece wr1 = new Piece("white","rook"), br1 = new Piece("black","rook");
      wr1.putOnSquare(square[1][1]); br1.putOnSquare(square[1][8]);
      Piece wr2 = new Piece("white","rook"), br2 = new Piece("black","rook");
      wr2.putOnSquare(square[8][1]); br2.putOnSquare(square[8][8]);
      Piece wb1 = new Piece("white","bishop"), bb1 = new Piece("black","bishop");
      wb1.putOnSquare(square[3][1]); bb1.putOnSquare(square[3][8]);
      Piece wb2 = new Piece("white","bishop"), bb2 = new Piece("black","bishop");
      wb2.putOnSquare(square[6][1]); bb2.putOnSquare(square[6][8]);
      Piece wkt1 = new Piece("white","knight"), bkt1 = new Piece("black","knight");
      wkt1.putOnSquare(square[2][1]); bkt1.putOnSquare(square[2][8]);
      Piece wkt2 = new Piece("white","knight"), bkt2 = new Piece("black","knight");
      wkt2.putOnSquare(square[7][1]); bkt2.putOnSquare(square[7][8]);
		for (i = 1; i <= 8; i++) {
         Piece wpn = new Piece("white","pawn"), bpn = new Piece("black","pawn");
         wpn.putOnSquare(square[i][2]); bpn.putOnSquare(square[i][7]);
      }
		//set the turn and build whitePieces,blackPieces vectors based on square[][]                                                                
		setTurn("white"); //default
		setPieces(square);
	}

	public Position(Field[][] f)
	{
		//create 64 new squares
		for (int i = 1; i <= 8; i++) for (int j = 1; j <= 8; j++)
		{
			//new square is created and receives its coordinates from f[i][j]
			square[i][j] = new Square(f[i][j]); 
			//new square receives its piece
			if (f[i][j].piece == null) square[i][j].piece = null;
			else {Piece p = new Piece(f[i][j].piece); p.putOnSquare(square[i][j]);}
		}
		setTurn("white"); //default
		setPieces(square);
	}

	public Position(Field[][] f, String t)
	{
		//create 64 new squares
		for (int i = 1; i <= 8; i++) for (int j = 1; j <= 8; j++)
		{
			//new square is created and receives its coordinates from f[i][j]
			square[i][j] = new Square(f[i][j]); 
			//new square receives its piece
			if (f[i][j].piece == null) square[i][j].piece = null;
			else {Piece p = new Piece(f[i][j].piece); p.putOnSquare(square[i][j]);}
		}
		setTurn(t); //default
		setPieces(square);
	}

	//2D array [9][9] - 64 squares, which, in turn, have links to the pieces
   public Position(Square[][] s)
   {
      for (int i = 1; i <= 8; i++) for (int j = 1; j <= 8; j++) square[i][j] = s[i][j];
      setTurn("white"); //default
      setPieces(square);   
   }
   public Position(Square[][] s, String t)
   {
      for (int i = 1; i <= 8; i++) for (int j = 1; j <= 8; j++) square[i][j] = s[i][j];
      setTurn(t); 
      setPieces(square);   
   }

	public Position(Position pos)
	{
		for (int i = 1; i <= 8; i++) for (int j = 1; j <= 8; j++) 
		{
			//new square is created and receives its coordinates from pos.square[i][j]
			square[i][j] = new Square(i,j);
			//new square receives its piece
			if (pos.square[i][j].piece == null) square[i][j].piece = null;
			else {Piece p = new Piece(pos.square[i][j].piece); p.putOnSquare(square[i][j]);}
		}
		//copy moveStack
		moveStack = (Stack) pos.moveStack.clone();
		setTurn(pos.turn);
		//sets whitePieces,blackPieces vectors
		setPieces(square);
	}

	public Position(Position pos, Move m)
	{
		for (int i = 1; i <= 8; i++) for (int j = 1; j <= 8; j++) 
		{
			//new square is created and receives its coordinates from pos.square[i][j]
			square[i][j] = new Square(i,j);
			//new square receives its piece
			if (pos.square[i][j].piece == null) square[i][j].piece = null;
			else {Piece p = new Piece(pos.square[i][j].piece); p.putOnSquare(square[i][j]);}
		}
		//copy moveStack
		moveStack = (Stack) pos.moveStack.clone();
		setTurn(pos.turn);
		//sets whitePieces,blackPieces vectors
		setPieces(square);
		//now, make move; Move m refers to src,dest,victim from pos, so I must redirect them
		Move mv = new Move(m);
		mv.srcsqr = square[m.srccol][m.srcrow]; 
		mv.destsqr = square[m.destcol][m.destrow];
		if (m.victpiece != null) {
		mv.victpiece = square[m.victcol][m.victrow].piece;
		}
		makeMove(mv);
	}
   
   //fills vectors whitePieces,blackPieces with pieces that occupy given array of squares
	//and sorts in increasing order (king,queen,rook,bishop,knight,pawn)
	private void setPieces(Square[][] s)
   {
      for (int i = 1; i <= 8; i++) {
         for (int j = 1; j <= 8; j++) {
            Piece p = s[i][j].piece;
            if (p == null) continue;
            if (p.owner.equals("white")) whitePieces.addElement(p);
            else if (p.owner.equals("black")) blackPieces.addElement(p);
            else System.out.println("piece " + p.name + " has no owner!");
         }
      }
      sort(whitePieces);
      sort(blackPieces);
   }
	//in the order king,quuen,rook,bishop,knight,pawn
   private void sort(Vector v)
   {
      for (int j = v.size() - 1; j >= 1; j--)
      {
         for (int i = 0; i <= j-1; i++)
         {
            Piece p1 = (Piece) v.elementAt(i), p2 = (Piece) v.elementAt(i+1);
            if (p1.compareName(p2) == -1) swap(v,i,i+1);
         }
      }   
   }
   
   private void swap(Vector v, int i, int j)
   {
      Object o1 = v.elementAt(i), o2 = v.elementAt(j);
      v.setElementAt(o1,j); v.setElementAt(o2,i);
   }
   
   public Vector getWhitePieces() {return whitePieces;}
   public Vector getBlackPieces() {return blackPieces;}
	public Piece getMyKing()
	{
		Piece p = null;
		for (int i = 0; i < myPieces.size(); i++) {
			p = (Piece) myPieces.elementAt(i);
			if (p.name.equals("king")) return p;
		}
		return p;
	}
	public Piece getEnemyKing()
	{
		Piece p = null;
		for (int i = 0; i < enemyPieces.size(); i++) {
			p = (Piece) enemyPieces.elementAt(i);
			if (p.name.equals("king")) return p;
		}
		return p;
	}
   
   public void printPosition() {
		printWhitePieces(); printBlackPieces();
	}
	public void printWhitePieces() {
      System.out.print("White: "); printPieceSet(whitePieces);
   }
   public void printBlackPieces() {
      System.out.print("Black: "); printPieceSet(blackPieces);
   }
   private void printPieceSet() {
		if (turn.equals("white")) printPieceSet(whitePieces); else printPieceSet(blackPieces);
	}
	public String toString()
	{
		String str = turn + "'s move; ";
		str = str + "White: ";
		boolean flag = false;
		int i = 0;
 	   for (i = 0; i < whitePieces.size(); i++)
		{
			Piece p = (Piece)whitePieces.elementAt(i);
			if (p.name.equals("pawn") && !flag) {str = str + "pp: ";flag = true;}
			str = str + p.abbreviation() + p.getSquare().toString();
			if (i != whitePieces.size() - 1) str = str + ",";
		}
		str = str + "   Black: ";
		flag = false;
		for (i = 0; i < blackPieces.size(); i++)
		{
			Piece p = (Piece)blackPieces.elementAt(i);
			if (p.name.equals("pawn") && !flag) {str = str + "pp: ";flag = true;}
			str = str + p.abbreviation() + p.getSquare().toString();
			if (i != blackPieces.size() - 1) str = str + ",";
		}
		StringBuffer sb = new StringBuffer(str);
		if (sb.length() > 80) sb.insert(80,'\n');
		str = sb.toString();
		return str;
	}
	private void printPieceSet(Vector v)
   {
      boolean flag = false;
      sort(v);
      Enumeration e = v.elements();
      while (e.hasMoreElements())
      {
         Piece p = (Piece) e.nextElement();
         if (p.name.equals("pawn") && flag == false) {System.out.print("pp: "); flag = true;}
         System.out.print(p.abbreviation());
         System.out.print(p.getSquare().coords());
         if (e.hasMoreElements()) System.out.print(",");
      }
      System.out.println();
   }
   private void printMoves(Vector v)
   {
   //System.out.println("Possible moves in this position: ");   
	int size = v.size();
      for (int i = 0; i < size; i++)
      {
         if (i != 0 && i%10 == 0) System.out.println();
			Move m = (Move) v.elementAt(i);
         System.out.print(m.toString() + "(" + m.positionalMerit() + ")");
         if (i < size - 1) System.out.print(",");   
      }
      System.out.println();
   }
   
   public String getTurn() {return turn;}
   public void setTurn(String t) 
	{
		turn = t; 
		if (t.equals("white")) {myPieces = whitePieces; enemyPieces = blackPieces;}
		else {myPieces = blackPieces; enemyPieces = whitePieces;}
	}
   public void swapTurn() 
   {
      if (turn.equals("white")) {turn = "black"; myPieces = blackPieces; enemyPieces = whitePieces;}
      else if (turn.equals("black")) {turn = "white"; myPieces = whitePieces; enemyPieces = blackPieces;}
   } 
   //material of the player whose turn it is to move
	public int myMaterial()
	{
		int material = 0;
		Vector pieces;
		if (turn.equals("white")) pieces = whitePieces; else pieces = blackPieces;
		for (int i = 0; i < pieces.size(); i++) {
			Piece p = (Piece) pieces.elementAt(i);
			material += p.value();
		}
		return material;
	}
	//material of the other player
	public int enemyMaterial()
	{
		int material = 0;
		Vector pieces;
		if (turn.equals("white")) pieces = blackPieces; else pieces = whitePieces;
		for (int i = 0; i < pieces.size(); i++) {
			Piece p = (Piece) pieces.elementAt(i);
			material += p.value();
		}
		return material;
	}
	//advantage of the player whose turn it is to move; can be positive or negative
	//returns relative advantage (my material - enemy material)/(smaller of the two)
	//thus, if the turn changes, this will merely change the sign
	public double materialAdvantage()
	{
		double my = (double) myMaterial(), enemy = (double) enemyMaterial(), min;
		if (my < enemy) min = my; else min = enemy;
		//return (my - enemy) / min;
		return my-enemy;
	}

   //sets enpasse to false for all pawns in this Vector of pieces
   //meaning that they can't now be taken en passe
   private void removeEnPasse(Vector v)
   {
      for (int i = 0; i < v.size(); i++) 
      {
         Piece p = (Piece) v.elementAt(i);
         if (p.name.equals("pawn")) p.enpasse = false;
      }
   }
   
	//checks if the information provided in m is self-consistent
	/*private boolean checkConsistency(Move m)
   {
      //Square srcsqr = m.srcsqr, destsqr = m.destsqr; Piece victpiece = m.victpiece; String transforms = m.transforms; String castle = m.castle; boolean enpasse = m.enpasse;
      if (m.srcsqr == m.destsqr) return false;
		if ((m.srcsqr == null) || (m.destsqr == null)) return false;
      if (m.srcpiece == null) return false; //empty square
      if ((m.destsqr.piece != null) && (m.srcpiece.owner.equals(dest.piece.owner))) return false; //can't capture piece of the same color
      return true;
   }
	*/
	/*public boolean checkValidity(Move m)
   {    
      if ((m.srccol == m.destcol) && (m.srcrow == m.destrow)) return false;
      if (m.srcpiece == null) return false; //empty square
      if ((m.destfld.piece != null) && (m.srcpiece.getOwner() == m.destfld.piece.getOwner())) return false; //can't capture piece of the same color
      if (!m.srcpiece.getOwner().equals(user)) return false; //can't move with the enemy piece
      return true;
   }
	*/
   //makes an actual change in the position; different from Chess's makeMove()
   //assumes: m already has all the relevant data members set to their values
	public Move makeMove(Move m)
   {
      //if (!checkConsistency(m)) {return null;}
		//else {/*System.out.println("making move " + m.toString());*/}
		m.produceAuxiliaryVariables(this);
		//update status
		updateStatusOfPieces(m);
		//remove victim piece from the vector 
      if (m.victpiece != null)  
      {
         if (m.victpiece.owner.equals("white")) whitePieces.removeElement(m.victpiece);
         if (m.victpiece.owner.equals("black")) blackPieces.removeElement(m.victpiece);      
      }
		//remove victim piece from the board
		if (m.victpiece != null) m.victsqr.setPiece(null);
      //if pawn reached the last row, replace it with the new piece
      if (m.transforms != 0)    //pawn turns into queen/rook/bishop/knight
      {
         m.srcpiece.transform(m.transforms);
      }
 	   //piece remembers its new square, old and new squares are informed about the change
		m.srcpiece.putOnSquare(m.destsqr);
      //if it's a castle, the rook moves as well
		if (m.castle != 0)
		{
			if (m.castle == 1) m.prtnrpiece.putOnSquare(square[6][m.srcrow]);
			if (m.castle == 2) m.prtnrpiece.putOnSquare(square[4][m.srcrow]);
		}

      //remember the move
      Move mv = new Move(m);    
      moveStack.push(mv);
      
		//System.out.println("...done");
		//printPosition();
		//System.out.println();
      swapTurn();
		
      return mv; 
   }

	public Move goBack()
	{
		Piece tp;                           //temporary piece
		Move m = (Move) moveStack.pop();
		//put the src piece to the original square
	 	tp = square[m.destcol][m.destrow].piece; //my piece that moved
		if (m.transforms != 0) {tp.transform("pawn");} //transform it back to the pawn if needed
		tp.enpasse = m.srcenpasse;						    //restore its enpasse status
		tp.cancastle = m.srccancastle;					 //restore its cancastle status
		tp.putOnSquare(square[m.srccol][m.srcrow]);    //put it back on original square
		//and the partner piece, if necessary
		if (m.castle == 1)          
		{
			tp = square[6][m.prtnrrow].piece;      //the rook can be found on the "f" file
 		   tp.putOnSquare(square[8][m.prtnrrow]); //goes back to the "h" file
		}
		if (m.castle == 2)
		{
			tp = square[4][m.prtnrrow].piece;
			tp.putOnSquare(square[1][m.prtnrrow]);
		}
		//restore the victim piece
		if (m.victcol != 0 && m.victrow != 0)
		{
			Piece p = new Piece(m.victowner,m.victname);
			p.enpasse = m.victenpasse;								  //restore victim's enpasse status
			p.cancastle = m.victcancastle;						  //restore victim's cancastle status
			p.putOnSquare(square[m.victcol][m.victrow]);		        //put it where it was
			if (p.owner.equals("white")) whitePieces.addElement(p); //and add it to the vector of pieces 
         if (p.owner.equals("black")) blackPieces.addElement(p); 
		}
		//restore the beneficiary's enpasse status
		if (m.bencol != 0 && m.benrow != 0)
		{
			square[m.bencol][m.benrow].piece.enpasse = true;
		}
		//restore the turn that existed before the move
		swapTurn();
		return m;
	}

	//assumes the move was already checked and found to be valid but not yet made
	//updates each piece's status, i.e. right to castle, to be taken en passe
	private void updateStatusOfPieces(Move m)
	{
		//if king or rook has moved, it loses right to castle
		if (m.srcpiece.name.equals("king") || m.srcpiece.name.equals("rook")) m.srcpiece.cancastle = false;
		//all remaining enemy pawns lose their enpasse status
		if (m.srcpiece.owner.equals("white")) //i am white
         removeEnPasse(blackPieces);
      else                              //i am black
         removeEnPasse(whitePieces);
		//my moving pawn can also acquire an enpasse status
		//(if it loses it, this will be taken care of during the enemy's move) 
		if (m.srcpiece.name.equals("pawn"))
		{
			if (m.srccol == m.destcol)
				if ((m.srcrow - m.destrow == 2) || (m.srcrow - m.destrow == -2))
					m.srcpiece.enpasse = true;
		}
	}
   
   public Move findBestMove()
	{
		Vector myMoves = findBestMoves();
		return findBestMove(myMoves);
	}

	public Move findBestMove(Vector myMoves)
	{
		if (myMoves == null) return null;
		System.out.println("Choosing best move from ");
		printMoves(myMoves);
		double curEstimate = materialAdvantage();
		System.out.println("current position's estimate = " + curEstimate);
		double maxEstimate = -1000;
		Move bestMove = (Move) myMoves.elementAt(0);
		for (int i = 0; i < myMoves.size(); i++)
		{
		Move m = (Move) myMoves.elementAt(i);  //take one move
		m.produceAuxiliaryVariables(this);     //match its variables with this position
		Position p = new Position(this,m);     //make the new position
		double estimate = p.estimatePosition(2); //estimate for user since it's now user's turn
		estimate = -estimate;   //estimate for computer
		if (estimate > maxEstimate) {maxEstimate = estimate;bestMove = m;}
		System.out.println("move " + m.toString() + ": estimate = " + estimate);
		}
		System.out.println("maxEstimate = " + maxEstimate);
		///////////////////////////////////
		Move mv = bestMove;
      //Move mv = (Move) myMoves.elementAt(0);
      System.out.println("generated " + mv.toString());
		System.out.println("...done");
      return mv;
      
	}

	public Vector findBestMoves()
	{
		Vector myMoves = possibleMoves();
		if (myMoves.size() == 0) return null;
		//estimate each move
		for (int i = 0; i < myMoves.size(); i++)
		{
			Move m = (Move) myMoves.elementAt(i);  //take one move
			m.produceAuxiliaryVariables(this);     //match its variables with this position
			Position p = new Position(this,m);     //make the new position
			double estimate = p.estimatePosition(1);    //estimate for user since it's now user's turn
			m.estimate = -estimate;                //estimate for computer
			m.estimate += m.positionalMerit();     //add positional component of the move's estimate
		}
		//perform bubble sort on myMoves to sort by estimate
		for (int j = myMoves.size() - 1; j >= 1; j--)
      {
         for (int i = 0; i <= j-1; i++)
         {
            Move m1 = (Move) myMoves.elementAt(i), m2 = (Move) myMoves.elementAt(i+1);
            if (m1.estimate < m2.estimate) {myMoves.setElementAt(m1,i+1); myMoves.setElementAt(m2,i);}
         }
      }
		System.out.println("Possible moves: ");
		printMoves(myMoves);
   	//now best moves are in the beginning of myMoves, discard all others
		if (myMoves.size() > 5) myMoves.setSize(5);
		//print the best moves
		String str = "best moves are: ";
		for (int k = 0; k < myMoves.size(); k++) {
			Move m = (Move) myMoves.elementAt(k);
			str = str + m.toString() + "(" + m.estimate + "), ";
		}
		System.out.println(str);
		return myMoves;
	}

	//from the point of view of the player whose turn it is to move
	public double estimatePosition(int depth)	  //depth- the number of half-moves
	{
		if (depth == 0) return materialAdvantage(); //default way to estimate when I have run out of depth
		Vector myMoves = possibleMoves();			//possible moves
		double maxEstimate = -1000;	  //best "child" position for myself
		for (int i = 0; i < myMoves.size(); i++)  //for each of them
		{
			Move m = (Move) myMoves.elementAt(i);  //take one move
			makeMove(m);
			double estimate = estimatePosition(depth-1);  //my opponent's estimate
			estimate = -estimate;								 //my estimate
			if (estimate > maxEstimate) maxEstimate = estimate; //find minimal estimate
			goBack();
		}
		//now, if the best I can do is to make +2 for my opponent, then it's -2 for me
		return (maxEstimate); 
	}

	/*public Move findBestMove(int depth)
	{
		Vector myMoves = possibleMoves();
		Move curChoice = (Move) myMove.elementAt(0); //default choice
		double curEstimate = estimate();				   //estimate of current position
		if (depth == 0) return curChoice;

		for (int i = 0; i < myMoves.size(); i++)
		{
			Move m = (Move) myMoves.elementAt(i);
			Position p = new Position(this,m);  //try this move
			Move best = p.findBestMove(depth-1);			 //get best response that will follow from this position
			if (best.
		}
	}*/

	//returns a vector of moves that are possible in this position
	public Vector possibleMoves()
	{
		Vector myMoves = new Vector();
		Vector myPieces = (turn.equals("white")) ? whitePieces : blackPieces;
		Piece ben = findPotentialBeneficiary();
		//for each piece in myPieces
      for (int i = 0 ; i < myPieces.size(); i++) 
      {
         Piece p = (Piece) myPieces.elementAt(i);
         Vector temp = p.possibleMoves(square);	  //possible moves for this piece
         for (int j = 0 ; j < temp.size(); j++) { //add each of them to myMoves
				Move m = (Move)temp.elementAt(j);
				if (ben != null) {m.bencol = ben.getSquare().col; m.benrow = ben.getSquare().row;}  //set the Move's "beneficiary" fields
				//if (!myKingUnderCheck(m)) myMoves.addElement(m);
				if (m.buildMoveFromSrcAndDest(this) == true) myMoves.addElement(m);
			}
      }
		if (myMoves.size() == 0) {
			Square myKingSqr = getMyKing().getSquare();
			if (isThreatened(myKingSqr)) checkmate = true;
			else stalemate = true;
			//System.out.println("Warning!!! No possible moves in position\n" + toString());
			return new Vector();
		}
		return myMoves;
	}
	
	//will this move put my king under check
	public boolean myKingUnderCheck(Move m)
	{
		Vector myPieces = (turn.equals("white")) ? whitePieces : blackPieces;
		Piece myKing = (Piece) myPieces.elementAt(0);
		Square myKingSqr = myKing.getSquare();
		//1) king is the source piece
		if (m.srccol == myKingSqr.col && m.srcrow == myKingSqr.row) 
		{
			if (isThreatened(square[m.destcol][m.destrow])) return true;
			if (m.castle != 0) {		   //if castle, check intermediary squares
				if (PositionAnalysis.noCheckDuringCastle(m,this) == false) return true;
			}
			return false;
		}
		//king doesn't move
		else												
		{
			//do I expose it to check by moving a pinned piece?
			//that won't happen if the pinned piece captures the attacker
			Piece attacker = new Piece();
			if (isPinned(myKingSqr,square[m.srccol][m.srcrow],attacker)) 
				if (square[m.destcol][m.destrow] != attacker.getSquare()) return true; 
			//is it under check now and my move fails to defend it?
			if (!isThreatened(myKingSqr)) return false;
			else    //my king is under check, do I fail to defend it?
			{
				//System.out.println("findThreateningSquares(" + myKingSqr.toString() + ")");
				Vector thrSqs = findThreateningSquares(myKingSqr);
				if (thrSqs.size() == 2) return true;  //no defense from double check
				Square thrSq = (Square)thrSqs.elementAt(0);  //it's a single check
				if (m.victcol == thrSq.col && m.victrow == thrSq.row) return false; //I capture the threatening piece
				if (isDefending(square[m.destcol][m.destrow],myKingSqr,thrSq)) return false; //I defended my king
				return true;
			}
		}
	}
	//am I under check right now?
	public boolean myKingUnderCheck()
	{
		Move m = (Move) moveStack.peek();
		if (m.check) return true; 
		else return false;
	}

	//is this square dangerous to my pieces?
	public boolean isThreatened(Square sq)
	{
		for (int i = 0; i < enemyPieces.size(); i++) {
			Piece p = (Piece) enemyPieces.elementAt(i);
			Square s = p.getSquare();
			//if the enemy piece is on sq itself, it's NOT dangerous
			//('cause when my piece goes to sq, this enemy piece will be captured)
			if (s.col == sq.col && s.row == sq.row) continue;
			if (threatens(s,sq)) return true;
		}
		return false;
	}
	//is piece on sq1 threatening square sq2?
	public boolean threatens(Square sq1, Square sq2)
	{
		int relloc = Chessboard.relativeLocation(sq1,sq2);
		if (relloc == Chessboard.NOT_RELATED) return false;
		if (relloc == Chessboard.SAME_KNIGHT_MOVE && sq1.piece.name.equals("knight")) return true;
		if (pieceBetween(sq1,sq2,relloc)) return false;
		//no piece between them, so now threat would be real
		if ((relloc == Chessboard.SAME_VER || relloc == Chessboard.SAME_HOR) && (sq1.piece.name.equals("rook") || sq1.piece.name.equals("queen"))) return true;
		if (relloc == Chessboard.SAME_DIAG && (sq1.piece.name.equals("bishop") || sq1.piece.name.equals("queen"))) return true;
		if (sq1.piece.name.equals("pawn") && Chessboard.withinPawnAttackingRange(sq1,sq2,sq1.piece.owner)) return true;
		if (sq1.piece.name.equals("king") && Chessboard.withinKingRange(sq1,sq2)) return true; 
		return false;
	}
	//will piece given by name when put on sq1 threaten square sq2?
	public boolean threatens(Square sq1, String name, Square sq2)
	{
		int relloc = Chessboard.relativeLocation(sq1,sq2);
		if (relloc == Chessboard.NOT_RELATED) return false;
		if (relloc == Chessboard.SAME_KNIGHT_MOVE && name.equals("knight")) return true;
		//strictly speaking, the very move that I am considering 
		//(when piece "name" moves to sq1) might remove the pieceBetween condition
		//(i.e. the piece is ALREADY between sq1,sq2), but I neglect this
		//because if I am ALREADY threatening sq2 then I probably won't
		//postpone this threat
		if (pieceBetween(sq1,sq2,relloc)) return false;
		//no piece between them, so now threat would be real
		if ((relloc == Chessboard.SAME_VER || relloc == Chessboard.SAME_HOR) && (name.equals("rook") || name.equals("queen"))) return true;
		if (relloc == Chessboard.SAME_DIAG && (name.equals("bishop") || name.equals("queen"))) return true;
		//I assume it's the player whose turn it is will put his pawn on sq1
		if (name.equals("pawn") && Chessboard.withinPawnAttackingRange(sq1,sq2,turn)) return true;
		if (name.equals("king") && Chessboard.withinKingRange(sq1,sq2)) return true; 
		return false;
	}

	//is piece on sq2 pinned because it defends piece on sq1?
	//if yes, puts the attacking piece into whoPins
   public boolean isPinned(Square sq1,Square sq2, Piece whoPins)
	{
		int relloc = Chessboard.relativeLocation(sq1,sq2);
		if (relloc == Chessboard.NOT_RELATED || relloc == Chessboard.SAME_KNIGHT_MOVE) return false;
		if (pieceBetween(sq1,sq2,relloc)) return false;  //can't be pinned 'cause there are pieces in between
		Square s1,s2;
		int i,j,incr;
		if (relloc == Chessboard.SAME_VER)	 //does anyone threaten s2 from this vertical?
		{
			incr = (sq1.row < sq2.row) ? 1 : -1;
			for (i = sq2.col, j = sq2.row + incr; j >= 1 && j <= 8; j += incr) {
				Piece p = square[i][j].piece;
			 	if (p == null) continue;
				if (p.owner.equals(sq1.piece.owner)) return false; //encountered my own piece, so there's no pin
				if (p.name.equals("rook") || p.name.equals("queen")) {whoPins.setSquare(p.getSquare()); return true;}
				else return false; //any other enemy piece is not dangerous
			}
		}
		if (relloc == Chessboard.SAME_HOR)
		{
			incr = (sq1.col < sq2.col) ? 1 : -1;
			for (i = sq2.col + incr, j = sq2.row; i >= 1 && i <= 8; i += incr) {
				Piece p = square[i][j].piece;
			 	if (p == null) continue;
				if (p.owner.equals(sq1.piece.owner)) return false; //encountered my own piece, so there's no pin
				if (p.name.equals("rook") || p.name.equals("queen")) {whoPins.setSquare(p.getSquare()); return true;}
				else return false; //any other enemy piece is not dangerous
			}
		}
		if (relloc == Chessboard.SAME_DIAG)
		{
			incr = (sq1.col < sq2.col) ? 1 : -1;
			int incr2 = (sq1.row < sq2.row) ? 1 : -1;
			for (i = sq2.col + incr, j = sq2.row + incr2; i>=1 && i<= 8 && j>=1 && j <= 8; i+=incr, j+=incr2) {
				Piece p = square[i][j].piece;
			 	if (p == null) continue;
				if (p.owner.equals(sq1.piece.owner)) return false; //encountered my own piece, so there's no pin
				if (p.name.equals("bishop") || p.name.equals("queen")) {whoPins.setSquare(p.getSquare()); return true;}
				else return false; //any other enemy piece is not dangerous
			}
		}
		return false;
	}
	//Vector of Squares whose pieces threaten Square sq
	public Vector findThreateningSquares(Square sq)
	{
		Vector vectSquares = new Vector();
		for (int i = 0; i < enemyPieces.size(); i++) {
			Piece p = (Piece) enemyPieces.elementAt(i);
			Square s = p.getSquare();
			int relloc = Chessboard.relativeLocation(sq,s);
			if (relloc == Chessboard.NOT_RELATED) continue; //s doesn't threaten sq - they are not connected by a piece move
			if (relloc == Chessboard.SAME_KNIGHT_MOVE && p.name.equals("knight")) {vectSquares.addElement(s); continue;}
			if (pieceBetween(sq,s,relloc)) continue; //s doesn't threaten sq - there is piece between them
			//no piece between them, so now threat would be real
			if ((relloc == Chessboard.SAME_VER || relloc == Chessboard.SAME_HOR) && (p.name.equals("rook") || p.name.equals("queen"))) {vectSquares.addElement(s);continue;}
			if (relloc == Chessboard.SAME_DIAG && (p.name.equals("bishop") || p.name.equals("queen"))) {vectSquares.addElement(s);continue;}
			if (p.name.equals("pawn") && Chessboard.withinPawnAttackingRange(s,sq,p.owner)) {vectSquares.addElement(s);continue;}
			if (p.name.equals("king") && Chessboard.withinKingRange(s,sq)) vectSquares.addElement(s);
		}
		return vectSquares;
	}
	//is defender defending target from attacker?
	//similar to isPinned(), with the difference that attacker is known
	//Also, isPinned() tells if "defender" piece is NESESSARY for defence
   //while isDefending() tells if it is SUFFICIENT for defence
	//The attack must be real, because I don't check it
	public boolean isDefending(Square defender, Square target, Square attacker)
	{
		////no defence from enemy knight,pawn, or king
		if (attacker.piece.name.equals("knight")) return false; 
		if (attacker.piece.name.equals("pawn")) return false;
		if (attacker.piece.name.equals("king")) return false;
		//no defence if attacker and target are adjacent
		if (Chessboard.squaresAdjacent(attacker,target)) return false;
		//is it a defence from queen,rook, or bishop?
		if (Chessboard.isBetween(defender,target,attacker)) return true;
		return false;
	}
	//is there a piece between sq1 and sq2, given their relative location?
	//assumes that sq1 and sq2 are on the same vertical,horizontal, or diagonal
	public boolean pieceBetween(Square sq1,Square sq2,int relloc)
	{
		int i,j;
		if (relloc == Chessboard.SAME_VER) {
			for (i = sq1.col, j = Math.min(sq1.row,sq2.row) + 1; j < Math.max(sq1.row,sq2.row); j++)
 		   	if (square[i][j].piece != null) return true;
		}
		if (relloc == Chessboard.SAME_HOR) {
			for (j = sq1.row, i = Math.min(sq1.col,sq2.col) + 1; i < Math.max(sq1.col,sq2.col); i++)
 		   	if (square[i][j].piece!= null) return true;
		}
		if (relloc == Chessboard.SAME_DIAG) {
			Square s1,s2;		 //s1 = "left" square, s2 = "right" square
			if (sq1.col < sq2.col) {s1=sq1; s2=sq2;} else {s1=sq2; s2=sq1;}
			i = s1.col; j = s1.row; 
			int incr = (Chessboard.diagDetails(sq1,sq2) == Chessboard.DIAG_SLASH) ? 1 : -1; 
 		   for (i = s1.col + 1, j = s1.row + incr; i < s2.col; i++,j+=incr)
				if (square[i][j].piece != null) return true;
		}
		return false;
	}

	//find an enemy pawn that has its enpasse flag set
	//it will be the beneficiary of my next move if I don't capture it
	private Piece findPotentialBeneficiary()
   {
		Vector enemyPieces = (turn.equals("white")) ? blackPieces : whitePieces;
		for (int i = 0; i < enemyPieces.size(); i++)
		{
			Piece p = (Piece)enemyPieces.elementAt(i);
			if (p.name.equals("pawn") && p.enpasse == true) return p;
		}
		return null;
	}
}
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    color: #463734;
    width: 125px;
    cursor: pointer;
    height: 38px;
    border: none;
}
form#header_search input[type="text"]:focus ~ input[type='button']:hover,
form#header_search input[type='button']:hover {
    background-color: #A5CE56;
    color: #fff;
}
form#header_search input[type="text"]:focus ~ input[type='button'] {
    background-color: #52AEDF;
    color: #fff;
}

</style>

<script>
function searchit(){
    
    // determine environment 
    var search_env 
    if (lycos_ad_www_server.indexOf(".pd.") > -1) {
       search_env = 'http://search51.pd.lycos.com/a/';
    } else if (lycos_ad_www_server.indexOf(".qa.") > -1) {
       search_env = 'http://search51.qa.lycos.com/a/';
    } else {
       search_env = 'http://search51.lycos.com/a/';
    }

var search_term = encodeURIComponent(document.search.search2.value)
var search_url = search_env+search_term;
window.open(search_url);

return false
}
</script-->
<style>
    .adCenterClass{margin:0 auto}
</style>
<div id="tb_ad" class="adCenterClass" style="display:block!important; overflow:hidden; width:916px;">

<div id="ad_container" style="display:block!important; float:left; width:728px ">
<script type="text/javascript">
if (typeof lycos_ad !== "undefined" && "leaderboard" in lycos_ad) {
  document.write(lycos_ad['leaderboard']);
}
</script>
</div>
</div>
</div>
<script type="text/javascript">
if (typeof lycos_ad !== "undefined" && "slider" in lycos_ad) {
  document.write(lycos_ad['slider']);
}
</script> <!-- added 7/22 -->
<div id="FooterAd" style="background:#DFDCCF; border-top:1px solid #393939; clear:both; display:none; width:100%!important; position:relative; z-index:999999!important; height:90px!important"> 
<div class="adCenterClass" style="display:block!important; overflow:hidden; width:916px;">
<div id="footerAd_container" style="display:block!important; float:left; width:728px">
<iframe id="lycosFooterAdiFrame" style="border:0; display:block; float:left; height:96px; overflow:hidden; padding:0; width:750px"></iframe>
</div>
</div>
</div>