package tins2020

import (
	"errors"
	"regexp"

	"github.com/veandco/go-sdl2/sdl"
)

var hexColorRE = regexp.MustCompile(`^#?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})-?([0-9A-Fa-f]{2})?$`)

func HexColor(s string) (sdl.Color, error) {
	match := hexColorRE.FindStringSubmatch(s)
	if match == nil {
		return sdl.Color{}, errors.New("invalid color format")
	}
	values, err := HexToInts(match[1:]...)
	if err != nil {
		return sdl.Color{}, err
	}
	a := 255
	if len(match[4]) > 0 {
		a = values[3]
	}
	return sdl.Color{R: uint8(values[0]), G: uint8(values[1]), B: uint8(values[2]), A: uint8(a)}, nil
}

func HexToInt(s string) (int, error) {
	var i int
	for _, c := range s {
		i *= 16
		if c >= '0' && c <= '9' {
			i += int(c - '0')
		} else if c >= 'A' && c <= 'F' {
			i += int(c - 'A' + 10)
		} else if c >= 'a' && c <= 'f' {
			i += int(c - 'a' + 10)
		} else {
			return 0, errors.New("hex digit not supported")
		}
	}
	return i, nil
}

func HexToInts(s ...string) ([]int, error) {
	ints := make([]int, len(s))
	for i, s := range s {
		value, err := HexToInt(s)
		if err != nil {
			return nil, err
		}
		ints[i] = value
	}
	return ints, nil
}