package main

import (
	"crypto/rand"
	"encoding/base64"
	"html/template"
	"strings"
)

var (
	funcs = template.FuncMap{
		"sub": func(a, b int) int {
			return a - b
		},
		"add": func(a, b int) int {
			return a + b
		},
	}
)

func generateStrongRandomString(length int) string {
	bytes := make([]byte, length)
	_, err := rand.Read(bytes)
	if err != nil {
		printErr("Error generating random string: %v", err)
	}
	return base64.URLEncoding.EncodeToString(bytes)[:length]
}

// Checks if the URL already includes a protocol
func hasProtocol(url string) bool {
	return strings.HasPrefix(url, "http://") || strings.HasPrefix(url, "https://")
}

// Checks if the domain is a local address
func isLocalAddress(domain string) bool {
	return domain == "localhost" || strings.HasPrefix(domain, "127.") || strings.HasPrefix(domain, "192.168.") || strings.HasPrefix(domain, "10.")
}

// Ensures that HTTP or HTTPS is befor the adress if needed
func addProtocol(domain string) string {
	if hasProtocol(domain) {
		return domain
	}
	if isLocalAddress(domain) {
		return "http://" + domain
	}
	return "https://" + domain
}