//NOT FINISHED

package main

import (
	"image"
	"image/png"
	"math/cmplx"
	"os"
)

type Color struct {
	r uint32
	g uint32
	b uint32
	a uint32
}

func (c Color) RGBA() (r, g, b, a uint32) {
	return c.r, c.g, c.b, c.a
}

func green() Color {
	return Color{0, 255, 0, 255}
}

func blue() Color {
	return Color{0, 0, 255, 255}
}

func main() {
	f, err := os.Create("out.png")
	if err != nil {
		os.Exit(1)
	}
	const (
		xmin, ymin, xmax, ymax = -2, -2, +2, +2
		width, height          = 1024, 1024
	)
	img := image.NewRGBA(image.Rect(0, 0, width, height))
	for py := 0; py < height; py++ {
		y := float64(py)/height*(ymax-ymin) + ymin
		for px := 0; px < width; px++ {
			x := float64(px)/width*(xmax-xmin) + xmin
			z := complex(x, y)
			img.Set(px, py, mandelbrot(z))
		}
	}
	png.Encode(f, img)
	f.Close()
}

func mandelbrot(z complex128) Color {
	const iterations = 200
	const contrast = 15
	var v complex128
	for n := uint8(0); n < iterations; n++ {
		v = v*v + z
		if cmplx.Abs(v) > 2 {
			return Color{0, uint32(255 - contrast*n), 0, 255}
		}
	}
	return blue()
}