package main

import (
	"image/color"
	"math/rand"
	"time"
)

type colorFunc func(float64, float64, time.Time) color.Color

func newColorFunc(c colormode) colorFunc {
	start := time.Now()
	return func(x, y float64, t time.Time) color.Color {
		var (
			r, g, b, a uint8
		)

		switch c {
		case crandom:
			r = uint8(rand.Intn(256))
			g = uint8(rand.Intn(256))
			b = uint8(rand.Intn(256))
			a = 255

		case ctimed:
			n := time.Since(start).Nanoseconds()

			r = uint8(n % 256)
			g = uint8((n + 128) % 256)
			//b = uint8((n + 1) % 256)

			a = 255

		case crainbow:
			r = uint8(y * 256)
			g = uint8(x * 256)
			b = uint8(((y - x) - min(x, y)) * 256)

			a = 255

		default:
			r, g, b, a = 0, 153, 0, 255
		}

		return color.RGBA{r, g, b, a}
	}
}