package main

import (
	"fmt"
	"math/big"
	"time"
)

var rat4 = big.NewRat(4, 1)

func mandelbrot(x0, y0 *big.Rat) int {
	x := new(big.Rat)
	y := new(big.Rat)
	x2 := new(big.Rat)
	y2 := new(big.Rat)
	temp := new(big.Rat)
	i := 0
	for ; temp.Add(x2, y2).Cmp(rat4) <= 0; i++ {
		y.Add(y, y).Mul(y, x).Add(y, y0)
		x.Sub(x2, y2).Add(x, x0)
		x2.Mul(x, x)
		y2.Mul(y, y)
	}
	return (i-1)%6 + 1
}

func printMandelbrot(xMin, xRange, yMin, yRange *big.Rat) error {
	const (
		width  = 80
		height = 25
	)

	grid := make([]int, width*height)
	xStep := new(big.Rat).Quo(xRange, big.NewRat(int64(width), 1))
	yStep := new(big.Rat).Quo(yRange, big.NewRat(int64(height), 1))
	y := new(big.Rat)
	x := new(big.Rat)
	y.Set(yMin)
	for i := 0; i < height; i++ {
		x.Set(xMin)
		for j := 0; j < width; j++ {
			go func(i, j int, x, y *big.Rat) {
				grid[i*width+j] = mandelbrot(x, y)
			}(i, j, new(big.Rat).Set(x), new(big.Rat).Set(y))
			x.Add(x, xStep)
		}
		y.Add(y, yStep)
	}
	time.Sleep(time.Minute)
	for i := 0; i < height; i++ {
		for j := 0; j < width; j++ {
			fmt.Printf("\033[%dm ", 40+grid[i*width+j])
		}
		fmt.Println("\033[49m")
	}
	return nil
}

func main() {
	printMandelbrot(big.NewRat(-3, 2), big.NewRat(247, 100), big.NewRat(-112, 100), big.NewRat(224, 100))
}