//Java Checkers Applet
// Written by Dr. Roger Webster 

import java.applet.*;
import java.awt.*;
import java.util.*;
import java.net.*;
import java.applet.Applet;

public class javawin extends Applet     
{
	Frame window;
      TextArea textarea = new TextArea(5, 80);
      checkers mycheckers;
	boolean mousedragging = false;
	boolean trytomakemove = false;

  	public void init() 
  	{ 
		window = new Frame ("Webster's Java Checkers Window");
		window.setSize (800, 800);
      	textarea.setFont(new Font("Helvetica", Font.PLAIN, 12));
      	textarea.setEditable(false);
		window.add("North", textarea);
		textarea.appendText("hello Java Checkers Players\n");
      	mycheckers = new checkers();
		window.add("Center", mycheckers);
		window.show();
  	}

  	public void stop() 
  	{
		window.dispose();
	}


class checkers extends Canvas 
{ 
	int grid = 8;
	int currentx, currenty;
	Color grey = new Color(165,165,165);//Board colors
	Color tan = new Color(255,255,204);	//Board colors
	int[][] BoardInfo = new int[8][8];	//Data structure for pieces
	int ActivePiece;
	int w, h;
	int FromX, FromY;
	int ToX, ToY;
	boolean you_go_first=true;
	boolean MyTurn;
	boolean AmIBlack;
	int nextx;
	int nexty;
	Graphics og;
	Image offScrImg;
	int imgWidth;
	int imgHeight;
	int width;
	int height;
	int checkerwidth;
	int checkerheight;
	int upcurrentx;
	int upcurrenty;
	int lastx;
	int lasty;
  // Initialization function
  	checkers() 
	{
 		super();		
		textarea.appendText("You are Black and you go first !\n");			
    		this.setup(you_go_first);
		width = size().width/grid;
		height = size().height/grid;
		imgWidth = width/7;
		imgHeight = height/7;
		w = width;
		h = height;
		checkerwidth = (int)(w/1.5);
		checkerheight = (int)(h/1.5);
  	}

   public void setup(boolean mefirst)
   {
   	int i,j;
		ActivePiece = 0;
		
		if(mefirst){
			MyTurn = true;
			AmIBlack = true;
		}else{
			MyTurn = false;
			AmIBlack = false;
		}
	    	
		for(i = 0;i < 8;i++)
			for (j = 0;j < 8;j++){
				if ((i == 3) || (i == 4)){ // No pieces on
					BoardInfo[j][i] = 0;
				}else if((i == 0) || (i == 2)){
					if ((j == 1)  || (j == 3) || (j ==5) || (j == 7)){
						BoardInfo[j][i] = 2;
					}
				}else if(i == 1){
					if ((j == 0)  || (j == 2) || (j ==4) || (j == 6)){
						BoardInfo[j][i] = 2;
					}
				}else if(i == 6){
					if ((j == 1)  || (j == 3) || (j ==5) || (j == 7)){
						BoardInfo[j][i] = 1;
					}
				}else if((i == 5) || (i == 7)){
					if ((j == 0)  || (j == 2) || (j ==4) || (j == 6)){
						BoardInfo[j][i] = 1;
					}
				}
			}
   	}

	public void DrawPiece(Graphics g, int x, int y, int Type) 
	{
		switch (Type) {
		
		case 1:		g.setColor(Color.red);
					g.fillOval(x,y, checkerwidth,checkerheight);
					break;
		case 2:		g.setColor(Color.black);
					g.fillOval(x,y, checkerwidth,checkerheight);
					break;
		case 3:		g.setColor(Color.red);
					g.fillOval(x,y, checkerwidth,checkerheight);
					g.setColor(Color.white);
				      g.setFont(new Font("Helvetica", Font.PLAIN, 18));
					g.drawString("K",x + checkerwidth/2, y + checkerheight/2);									
					break;
		case 4:		g.setColor(Color.black);
					g.fillOval(x,y, checkerwidth,checkerheight);
					g.setColor(Color.white);					
				      g.setFont(new Font("Helvetica", Font.PLAIN, 18));
					g.drawString("K",x + checkerwidth/2, y + checkerheight/2);									
					break;
		}
   	}

	void cliptoaffectedarea (Graphics g, int oldx, int oldy, int newx, int newy, int width, int height)
	{
		int x = Math.min(oldx, newx);
		int y = Math.min(oldy, newy);
		int w = ( Math.max(oldx, newx) + width) - x;
		int h = ( Math.max(oldy, newy) + height) - y;
		g.clipRect(x,y,w,h);
	}

     	public void update( Graphics g )
   	{
 		if (offScrImg == null)
			offScrImg = createImage(size().width, size().height);
		og = offScrImg.getGraphics();
 		lastx = upcurrentx-checkerwidth/2;
		lasty = upcurrenty-checkerheight/2;
		
		if (lastx > nextx)
			upcurrentx = nextx-checkerwidth;
		else
			upcurrentx = nextx +checkerwidth;
		if (lasty > nexty)
			upcurrenty = nexty-checkerwidth;
		else
			upcurrenty = nexty+checkerwidth;

	//	textarea.appendText("clipping lastx is" + lastx + " lasty is "+ lasty +"!\n");
	//	textarea.appendText("clipping upcurrentx is" + upcurrentx  + " upcurrenty  is "+ upcurrenty +"!\n");

		if (mousedragging)
		{
			cliptoaffectedarea (og, lastx, lasty, upcurrentx, upcurrenty, imgWidth, imgHeight);
			cliptoaffectedarea (g, lastx, lasty, upcurrentx, upcurrenty, imgWidth, imgHeight);
		}
		else
		{
			cliptoaffectedarea (og, 0, 0, size().width,  size().height, size().width,  size().height);
			cliptoaffectedarea (g, 0, 0, size().width,  size().height, size().width,  size().height);
		}
	
		paint(og);
		g.drawImage(offScrImg, 0, 0, this);
		og.dispose();
   	}
 
   // display the image
   public void paint( Graphics g )
   {
	 	boolean shade = false;
		int PieceType;

   		width = size().width/grid;
		height = size().height/grid;
		w = width;
		h = height;
		checkerwidth = (int)(w/1.5);
		checkerheight = (int)(h/1.5);
		imgWidth = checkerwidth;
		imgHeight = checkerheight;
		
		for (int y=0;y<=grid;y++)
			for (int x=0; x <= grid; x++)
			{
				g.setColor ( (shade = !shade) ? tan :grey);
				g.fillRect ( x * w, y * h, w, h);
			}
		
	
	    	for (int y = 0; y < grid; y++)   // Draw pieces on game board
	         for (int x = 0; x < grid; x++)
	  	   {
	        	if (BoardInfo[x][y] == 1)
			{
	        		PieceType = 1;
				DrawPiece(g, x * w + (w/7), y * h +(w/7), PieceType);

			}
			if (BoardInfo[x][y] == 2)
			{
	        		PieceType = 2;
				DrawPiece(g, x * w + (w/7), y * h +(w/7), PieceType);
			}
			if (BoardInfo[x][y] == 3)
			{
	        		PieceType = 3;
				DrawPiece(g, x * w + (w/7), y * h +(w/7), PieceType);
				
			 }
			if (BoardInfo[x][y] == 4)
			{
	        		PieceType = 4;
				DrawPiece(g, x * w + (w/7), y * h +(w/7), PieceType);	
			}
		   }

		if (mousedragging)	
		{
      		   DrawPiece(g, currentx, currenty, ActivePiece);
		}
	
     } //end of paint()

	public boolean mouseDown (Event e, int x, int y)
	{
	
			trytomakemove = false;
			FromX = FindXSquare(x);
			FromY = FindYSquare(y);
		//	textarea.appendText("FromX " + FromX + " FromY is "+ FromY +"!\n");			

			if((AmIBlack) && ((BoardInfo[FromX][FromY] == 2)||(BoardInfo[FromX][FromY] == 4)))
			{
					ActivePiece =BoardInfo[FromX][FromY];			
					BoardInfo[FromX][FromY] = 0;
					trytomakemove = true;
					nextx = x;
					nexty = y;		
					currentx = x;
					currenty = y;
					mousedragging = true;
					repaint();		
			}

			if((!AmIBlack) && ((BoardInfo[FromX][FromY]== 1)||(BoardInfo[FromX][FromY]== 3)))
			{	
					ActivePiece =BoardInfo[FromX][FromY];			
					BoardInfo[FromX][FromY] = 0;
					trytomakemove = true;
					nextx = x;
					nexty = y;		
					currentx = x;
					currenty = y;
					mousedragging = true;
					repaint();
			}
			
		return true;
	}	
	
	public boolean mouseUp (Event e, int x, int y)
	{
		Graphics g;
		
		ToX = FindXSquare(x);
		ToY = FindYSquare(y);
		mousedragging = false;	
		nextx = x;
		nexty = y;	
		
		if (trytomakemove)
		{
		//	textarea.appendText("FromX " + FromX + " FromY is "+ FromY +"!\n");			
		//	textarea.appendText("ToX " + ToX + " ToY is "+ ToY +"!\n");			
			MakeMove(FromX, FromY, ToX, ToY);	
			repaint();
		}
		trytomakemove = false;		
			return true;
	}	
	
	public boolean mouseDrag(Event e, int x, int y)
	{
		nextx = x;
		nexty = y;		
		if (trytomakemove)
		{
			currentx = x;
			currenty = y;
			mousedragging = true;
			repaint();
		}
		return true;
	}

	//Checks if a piece will become a king on this move
	//Also Checks if piece is already a king
	//this method written by Andrea Olson 
  	public boolean IsKing(int x, int y) 
	{
    		int ThePiece = ActivePiece;
		
    if ((ThePiece == 3) || (ThePiece == 4))  //piece is already king
      return true;
    else if (((ThePiece == 1) && (y == 0)) && ((x == 1) || (x == 3) || (x== 5) || (x == 7))) {
      ActivePiece = 3;
      return true;
    }
    else if ((ThePiece == 2) && (y == 7) &&   //piece is black and moving
            ((x == 0) || (x == 2) || (x == 4) || (x == 6))) {
      ActivePiece = 4;
      return true;
    }
    else 				//piece is not and will not become
      return false;
  }


  	//  Check valid move
  	//this method written by Andrea Olson 
	public boolean ValidMove() 
	{
    int MoveDifX = FromX - ToX;                // Difference of old X spot
    int MoveDifY = FromY - ToY;                // Difference of old Y spot

	 if(BoardInfo[ToX][ToY] != 0)	//Piece already there
	 	return false;

    if ((ActivePiece == 3) || (ActivePiece == 4)) {  // If King
      if (((MoveDifX == 1) || (MoveDifX == -1)) && ((MoveDifY == 1) || (MoveDifY == -1)))
        return true;
      else
        return false;
    }else if (ActivePiece == 1){  // If red player
      if (((MoveDifX == 1) || (MoveDifX == -1)) && (MoveDifY == 1))
        return true;
      else
        return false;
    }else if (ActivePiece == 2){ // If black player
      if (((MoveDifX == 1) || (MoveDifX == -1)) && (MoveDifY == -1))
        return true;
      else
        return false;
    }else{
    	return false;
    }
  }

	//this method written by Andrea Olson 
  public boolean ValidJump() {
    int MoveDifX = FromX - ToX;   // Difference of old X spotand new X spot
    int MoveDifY = FromY - ToY;   // Difference of old Y spotand new Y spot
    int JumpedPieceX = MoveDifX / -2 + FromX;   // Calculate where Xjumped piece is
    int JumpedPieceY = MoveDifY / -2 + FromY;   // Calculate where Yjumped piece is
    int JumpOverSpot = BoardInfo[JumpedPieceX][JumpedPieceY]; // Spot ofpiece to jump


	//Spot jumped is not empty and is not your own piece
    if ((JumpOverSpot != 0) && (JumpOverSpot % 2 != ActivePiece % 2)) { 
		BoardInfo[JumpedPieceX][JumpedPieceY] = 0;	 //Removejumped piece
      if ((ActivePiece == 3) || (ActivePiece == 4)) {  // If King
        if (((MoveDifX == 2) || (MoveDifX == -2)) && ((MoveDifY == 2) ||(MoveDifY == -2)))
          return true;
        else
          return false;
      }else if (ActivePiece == 1) {  // If red player
        if (((MoveDifX == 2) || (MoveDifX == -2)) && (MoveDifY == 2))
          return true;
        else
          return false;
      }else if(ActivePiece == 2) { // If black player 
        if (((MoveDifX == 2) || (MoveDifX == -2)) && (MoveDifY == -2))
          return true;
        else
          return false;
		}else
		  return false;
    }else
      return false;
  }


  	public int FindXSquare(int mousex) 
	{
    		int found = -1;              	
		int width = size().width/grid;
		int height = size().height/grid;
		found = mousex / width;
    		return found;
  	}

	public int FindYSquare(int mousey) 
	{
    		int found = -1;              	
		int width = size().width/grid;
		int height = size().height/grid;
		found = mousey / height;
    		return found;
  	}


	public void MakeMove(int fx, int fy, int tx, int ty)
	{
		if( ValidMove() || ValidJump() )
		{			
			if( (IsKing(ToX, ToY)) || (!IsKing(ToX, ToY)) )
			{
				BoardInfo[ToX][ToY] = ActivePiece;
				MyTurn = !MyTurn;
				AmIBlack = !AmIBlack;		
				if (MyTurn)
					textarea.appendText("It is now Black's turn !\n");
				else
					textarea.appendText("It is now Red's turn !\n");
		
			}			
		}
		else
			BoardInfo[FromX][FromY] = ActivePiece;
		
		ActivePiece = 0;
	}
}

}