package resolver

import (
	"hash/fnv"
	"regexp"
	"strconv"
	"strings"
)

var reANSI = regexp.MustCompile(`\x1B\[[0-9;]*[A-Za-z]`)

func UniqueStrings(in []string) []string {
	seen := map[string]struct{}{}
	var out []string
	for _, v := range in {
		if _, ok := seen[v]; !ok {
			seen[v] = struct{}{}
			out = append(out, v)
		}
	}
	return out
}

func PickDNSStartIndex(host string, size int) int {
	if size <= 1 {
		return 0
	}
	h := fnv.New32a()
	_, _ = h.Write([]byte(strings.ToLower(strings.TrimSpace(host))))
	return int(h.Sum32() % uint32(size))
}

func StripANSI(s string) string {
	return reANSI.ReplaceAllString(s, "")
}

func IsPrivateIPv4(ip string) bool {
	parts := strings.Split(strings.Split(ip, "/")[0], ".")
	if len(parts) != 4 {
		return true
	}
	vals := make([]int, 4)
	for i, p := range parts {
		n, err := strconv.Atoi(p)
		if err != nil || n < 0 || n > 255 {
			return true
		}
		vals[i] = n
	}
	if vals[0] == 10 || vals[0] == 127 || vals[0] == 0 {
		return true
	}
	if vals[0] == 192 && vals[1] == 168 {
		return true
	}
	if vals[0] == 172 && vals[1] >= 16 && vals[1] <= 31 {
		return true
	}
	return false
}