/*
 * Copyright (c) 2015 Camil Staps
 */
package com.camilstaps.mandelbrot;

import java.util.HashMap;
import java.util.Map;

/**
 *
 * @author camilstaps
 */
public class MandelbrotFractal {
    
    private static final Map<Point,Result> mandelNumbers = new HashMap<>();
    
    public static int mandelNumber(double x, double y, int repetitions) {
        Point p = new Point(x, y);
        return mandelNumber(p, repetitions);
    }
    
    public static int mandelNumber(Point p, int repetitions) {
        if (mandelNumbers.containsKey(p)) {
            Result result = mandelNumbers.get(p);
            if (repetitions < result.repetitions ||
                    result.mandelNumber < result.repetitions) {
                return result.mandelNumber;
            } else {
                calculateMandelNumber(p, repetitions, result);
                return result.mandelNumber;
            }
        } else {
            Result result = calculateMandelNumber(p, repetitions);
            mandelNumbers.put(p, result);
            return result.mandelNumber;
        }
    }
    
    protected static Result calculateMandelNumber(Point p, int repetitions) {
        Result start = new Result();
        start.x = p.x;
        start.y = p.y;
        calculateMandelNumber(p, repetitions, start);
        return start;
    }
    
    protected static void calculateMandelNumber(Point p, int repetitions, Result start) {
        int n = start.repetitions;
        
        while (start.x * start.x + start.y * start.y <= 4 && n <= repetitions) {
            double new_x = start.x * start.x - start.y * start.y + p.x;
            start.y = 2 * start.x * start.y + p.y;
            start.x = new_x;
            n++;
        }
        
        start.mandelNumber = n;
    }
    
    public static class Point {
        double x, y;
        
        public Point(double x, double y) {
            this.x = x;
            this.y = y;
        }
        
        @Override
        public boolean equals(Object another) {
            if (another == null || another.getClass() != Point.class) {
                return false;
            }
            Point that = (Point) another;
            return that.x == x && that.y == y;
        }

        @Override
        public int hashCode() {
            int hash = 7;
            hash = 97 * hash + (int) (Double.doubleToLongBits(this.x) ^ (Double.doubleToLongBits(this.x) >>> 32));
            hash = 97 * hash + (int) (Double.doubleToLongBits(this.y) ^ (Double.doubleToLongBits(this.y) >>> 32));
            return hash;
        }
        
        @Override
        public String toString() {
            return String.format("(%f,%f)", x, y);
        }
    }
    
    protected static class Result {
        int mandelNumber = -1, repetitions = -1;
        double x, y;
    }
    
}