package afreeca

import (
	"fmt"
	"math"
	"math/rand"
	"regexp"
	"strconv"
	"strings"
	"time"
)

const regexUserId = `^(?is)(\w+)(?:\(([0-9]+)\))?$`

func GenerateUID() string {
	mask := []string{"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"}
	arr := make([]string, 36)
	k := 0

	rand.New(rand.NewSource(time.Now().UnixNano()))

	for i := 0; i < 8; i++ {
		k++
		arr[k] = mask[int64(math.Floor(16*rand.Float64()))]
	}

	for i := 0; i < 3; i++ {
		for k := 0; k < 4; k++ {
			k++
			arr[k] = mask[int64(math.Floor(16*rand.Float64()))]
		}
	}

	hex := fmt.Sprintf("0000000%s",
		strings.ToUpper(strconv.FormatInt(time.Now().UnixNano()/int64(time.Millisecond), 16)))
	l := len(hex)
	hexMask := []byte(hex[l-8 : l])

	for i := 0; i < 8; i++ {
		k++
		arr[k] = string(hexMask[i])
	}

	for i := 0; i < 4; i++ {
		k++
		arr[k] = mask[int64(math.Floor(16*rand.Float64()))]
	}

	return strings.Join(arr, "")
}

func NormalizeUserID(s string) string {
	var (
		m      = regexp.MustCompile(regexUserId).FindStringSubmatch(s)
		groups int
		userId = strings.TrimSpace(s)
	)

	if groups = len(m); groups == 0 {
		return userId
	}

	return strings.TrimSpace(m[1])
}