//Percolation.java

import java.awt.*;
import javax.swing.*;

public class Percolation extends JApplet {     

    int rows, cols, percent, scale, rule;
    String sideflow;

    public void init() {

	String input;
	input = JOptionPane.showInputDialog("Enter # rows");
	rows = Integer.parseInt(input);
	input = JOptionPane.showInputDialog("Enter # columns");
	cols = Integer.parseInt(input);
	input = JOptionPane.showInputDialog("Random percentage rock");
	percent = Integer.parseInt(input);
	input = JOptionPane.showInputDialog("Pixel scale factor");
	scale = Integer.parseInt(input);
	input = JOptionPane.showInputDialog("Seepage rule:"+
					    "\n1. above or either diagonal"+
					    "\n2. above or both diagonals");
	rule = Integer.parseInt(input);
	sideflow = JOptionPane.showInputDialog("Side flow (yes or no)");

    }

    public void paint (Graphics g) {
	int [][]W = new int[rows][cols];

	for (int i=0; i<rows; i++)
	    for (int j=0; j<cols; j++)
		if (Math.random()<percent/100.0) {
		    W[i][j] = 1;   //rock
		    if (scale == 1)
			g.drawLine(j,i,j,i);
		    else
			g.fillRect(j*scale,i*scale,scale,scale);
		}
		else 
		    W[i][j] = 0;   //space.  init value...

	g.setColor(Color.RED);
	//initial row spaces to water.  "rain"
	for (int j=0; j<cols; j++)
	    if (W[0][j] == 0) {
		W[0][j] = 2;  //water
		if (scale == 1)
		    g.drawLine(j,0,j,0);
		else
		    g.fillRect(j*scale,0,scale,scale);
	    }
		    
	
	for (int i=1; i<rows; i++) {
	    for (int j=1; j<cols-1; j++)
		switch (rule) {
		case 1:
		    //if this is space and (above or upperleft or upperight is water)
		    if (W[i][j]==0 && (W[i-1][j]==2 || W[i-1][j-1]==2 || W[i-1][j+1]==2)) 
			W[i][j] = 2;     //water seeps to here
		    break;
		case 2:
		    //if this is space and (above or (upperleft and upperight is water))
		    if (W[i][j]==0 && (W[i-1][j]==2 || (W[i-1][j-1]==2 && W[i-1][j+1]==2)))
			W[i][j] = 2;     //water seeps to here
			break;
		}

	    if (sideflow.equalsIgnoreCase("yes")) {
		for (int j=0; j<cols-1; j++)    //"push" water to right nbor
		    if (W[i][j]==2 && W[i][j+1]==0)
			W[i][j+1] = 2;
		for (int j=cols-1; j>0; j--)    //reverse and "push" water to left nbor
		    if (W[i][j]==2 && W[i][j-1]==0)
			W[i][j-1] = 2;
	    }

	    //draw water for this row
	    for (int j=0; j<cols; j++)   
		if (W[i][j] == 2)
		    if (scale == 1)
			g.drawLine(j,i,j,i);
		    else
			g.fillRect(j*scale,i*scale,scale,scale);
	}

    }
}