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server {
    listen 80;
    server_name MY_DOMAIN;

    set $visitorCode "";

        if ($http_cookie ~* "kameleoonVisitorCode=([^;]+)") {
        set $visitorCode $1;
    }

        if ($visitorCode = "") {
        set_by_lua_block $visitorCode '{
            local alphabet = "abcdefghijklmnopqrstuvwxyz0123456789" 
            local code = "" 
            for i = 1, 16 do
                local randomNumber = math.random(1, #alphabet)
                code = code .. alphabet:sub(randomNumber, randomNumber)
            end
            return code
        }';
    }

    location / {
        add_header Set-Cookie "kameleoonVisitorCode=$visitorCode; Expires=$expires; Path=/; Domain=MY_DOMAIN;";
        return 204; 
    }
}

javax.servlet.http.HttpServletRequest request; // Provide a reference to the HttpServletRequest
javax.servlet.http.HttpServletResponse response; // Provide a reference to the HttpServletResponse
String topLevelDomain = "MY_DOMAIN";// Here you must provide your own base domain, for example, mydomain.com
String visitorCode = null; // Here you can provide your own identifier if needed, else the code generates one randomly

String cookiesHeader = request.getHeader("Cookie");
if (cookiesHeader != null) {
	String[] cookies = cookiesHeader.split(";");
	for (String cookieNameAndValue : cookies) {
		String[] cookieNameAndValuePair = cookieNameAndValue.split("=");
		if (cookieNameAndValuePair[0].trim().equals("kameleoonVisitorCode")) {
			visitorCode = cookieNameAndValuePair[1];
		}
	}
}
if (visitorCode == null) {
	final String alphabet = "abcdefghijklmnopqrstuvwxyz0123456789";
	final int alphabetLength = alphabet.length();
	final int visitorCodeLength = 16;
	final StringBuilder visitorCodeBuilder = new StringBuilder(visitorCodeLength);
	for (int i = 0; i < visitorCodeLength; ++i) {
		visitorCodeBuilder.append(
				alphabet.charAt(java.util.concurrent.ThreadLocalRandom.current().nextInt(alphabetLength))
		);
	}
	visitorCode = visitorCodeBuilder.toString();
}

javax.servlet.http.Cookie cookie = new Cookie("kameleoonVisitorCode", visitorCode);
cookie.setMaxAge(32_832_000);
cookie.setHttpOnly(false); // The cookie must be accessible from the front-end since it stores the visitorCode, which Kameleoon uses to bucket users into experiments and track their activity.
cookie.setPath("/");
cookie.setDomain(topLevelDomain);
response.addCookie(cookie);

let topLevelDomain = "MY_DOMAIN";// Here you must provide your own base domain, for example, mydomain.com
let visitorCode = null; // Here you can provide your own identifier if needed, else the code generates one randomly

request.headers && request.headers.cookie.split(';').forEach(function (cookie) {
	let cookieNameAndValuePair = cookie.match(/(.*?)=(.*)$/);
	if (cookieNameAndValuePair[1].trim() == "kameleoonVisitorCode") {
		visitorCode = cookieNameAndValuePair[2].trim();
	}
});
if (!visitorCode) {
	let alphabet = "abcdefghijklmnopqrstuvwxyz0123456789";
	let alphabetLength = alphabet.length;
	visitorCode = "";
	for (let i = 0; i < 16; ++i) {
		let randomNumber = Math.floor(Math.random() * alphabetLength);
		visitorCode += alphabet[randomNumber];
	}
}

let expires = new Date(new Date().getTime() + 32832000000);
response.writeHead(200, {
		'Set-Cookie': [`kameleoonVisitorCode=${visitorCode}; expires=${expires}; path=/; domain=${topLevelDomain};`]
});

<?php
$topLevelDomain = "MY_DOMAIN";// Here you must provide your own base domain, for example, mydomain.com
$visitorCode = NULL; // Here you can provide your own identifier if needed, else the code generates one randomly

if (isset($_COOKIE["kameleoonVisitorCode"])) {
	$visitorCode = $_COOKIE["kameleoonVisitorCode"];
}
if (is_null($visitorCode)) {
	$alphabet = "abcdefghijklmnopqrstuvwxyz0123456789";
	$alphabetLength = strlen($alphabet);
	$visitorCode = "";
	for ($i = 0; $i < 16; $i++) {
		$randomNumber = floor((mt_rand() / mt_getrandmax()) * $alphabetLength);
		$visitorCode .= substr($alphabet, $randomNumber, 1);
	}
}

setcookie("kameleoonVisitorCode", $visitorCode, time() + 32832000, "/", $topLevelDomain);
?>

var request *fasthttp.Request // Provide a reference to the Request
var response *fasthttp.Response // Provide a reference to the Response
const topLevelDomain = "MY_DOMAIN" // Here you must provide your own base domain, for example, mydomain.com
var visitorCode string // Here you can provide your own identifier if needed, else the code generates one randomly

if binaryVisitorCode := request.Header.Cookie("kameleoonVisitorCode"); binaryVisitorCode != nil {
	visitorCode = string(binaryVisitorCode)
}
if visitorCode == "" {
	const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789"
	const visitorCodeLength = 16
	visitorCodeBuilder := strings.Builder{}
	visitorCodeBuilder.Grow(visitorCodeLength)
	randomBuffer := make([]byte, visitorCodeLength)
	if _, err := rand.Read.Read(randomBuffer); err != nil { // crypto/rand
		// handle error
	}
	for i := 0; i < visitorCodeLength; i++ {
		visitorCodeBuilder.WriteByte(alphabet[randomBuffer[i] % len(alphabet)])
	}
	visitorCode = visitorCodeBuilder.String()
}

ck := fasthttp.AcquireCookie()
ck.SetKey("kameleoonVisitorCode")
ck.SetValue(visitorCode)
ck.SetExpire(time.Now().Add(380 * 24 * time.Hour))
ck.SetHTTPOnly(false) // The cookie must be accessible from the front-end since it stores the visitorCode, which Kameleoon uses to bucket users into experiments and track their activity.
ck.SetPath("/")
ck.SetDomain(topLevelDomain)
response.Header.SetCookie(ck)
fasthttp.ReleaseCookie(ck)

import random

topLevelDomain = "MY_DOMAIN" # Here you must provide your own base domain, for example, mydomain.com

# Here you can provide your own identifier via customer_visitor_code if needed, else the code generates one randomly
def fill_visitor_code(request, response, customer_visitor_code):
    visitor_code = request.cookies.get("kameleoonVisitorCode")
    if "kameleoonVisitorCode" in request.cookies:
        visitor_code = request.cookies.get("kameleoonVisitorCode")
    else:
        visitor_code = customer_visitor_code if customer_visitor_code is not None else "".join(
            random.choice(string.ascii_lowercase + string.digits) for _ in range(16)
        )
    response.set_cookie("kameleoonVisitorCode", visitor_code, max_age=32832000, domain=topLevelDomain)

fill_visitor_code(request, response) # The method must be called with correct arguments (depending on your Python web framework)

# Define constants
KAMELEOON_COOKIE_VALUE_LENGTH = 16
KAMELEOON_COOKIE_NAME = 'kameleoonVisitorCode'.freeze
EXPIRE_DAYS = 365

# Method to generate a random visitor code
def generate_visitor_code(length)
  alphabet = 'abcdefghijklmnopqrstuvwxyz0123456789'
  alphabet_length = alphabet.length
  visitor_code = ''

  length.times do
    random_number = rand(alphabet_length)
    visitor_code.concat(alphabet[random_number])
  end

  visitor_code
end

# Main code
top_level_domain = 'MY_DOMAIN' # Replace with your actual domain
visitor_code = cookies[KAMELEOON_COOKIE_NAME]

visitor_code = generate_visitor_code(KAMELEOON_COOKIE_VALUE_LENGTH) if visitor_code.nil? || visitor_code.empty?

kameleoon_cookie = {
  value: visitor_code,
  expires: Time.now + 60 * 60 * 24 * EXPIRE_DAYS,
  path: '/',
  domain: top_level_domain
}

cookies[KAMELEOON_COOKIE_NAME] = kameleoon_cookie