package utils

import (
	"fmt"
	"math"
)

const (
	Pred   float64 = 0.299
	Pgreen float64 = 0.587
	Pblue  float64 = 0.114
)

func IsDarkColor(r, g, b uint8) bool {
	lum := Luminance(r, g, b)

	return lum <= 130
}

func IntToRgb(color uint32) (uint8, uint8, uint8) {
	b := color % 256
	g := color / 256 % 256
	r := color / (256 * 256) % 256

	return uint8(r), uint8(g), uint8(b)
}

func RgbToString(r, g, b uint8) string {
	return fmt.Sprintf("#%02x%02x%02x", r, g, b)
}

func AltColor(r, g, b uint8) (uint8, uint8, uint8) {
	brightnessAmount := -0.6
	if IsDarkColor(r, g, b) {
		brightnessAmount = 0.85
	}
	return Brighten(r, g, b, brightnessAmount)
}

func Brighten(r, g, b uint8, amount float64) (uint8, uint8, uint8) {
	return multiply(r, amount), multiply(g, amount), multiply(b, amount)
}

func multiply(i uint8, amount float64) uint8 {
	iF := float64(i)
	return uint8(
		math.Max(
			0,
			math.Min(
				255, iF+255*amount,
			),
		),
	)
}

func Luminance(r, g, b uint8) float64 {
	rC := Pred * math.Pow(float64(r), 2)
	gC := Pgreen * math.Pow(float64(g), 2)
	bC := Pblue * math.Pow(float64(b), 2)

	return math.Sqrt(rC + gC + bC)
}

func WCAGRatio(l1, l2 float64) float64 {
	if l1 < l2 {
		return (l1 + 0.05) / (l2 + 0.05)
	} else {
		return (l2 + 0.05) / (l1 + 0.05)
	}
}