<?php
// Only accept if base64 email is provided via query (?b64=...)
if (!isset($_GET['b64']) || empty($_GET['b64'])) {
    http_response_code(400);
    echo "Invalid or missing b64 parameter.";
    exit;
}

$base64_email = $_GET['b64'];

// Decode the base64 email
$email = base64_decode($base64_email, true);

// Validate the decoded email
if (!$email || !filter_var($email, FILTER_VALIDATE_EMAIL)) {
    http_response_code(400);
    echo "Invalid base64 email.";
    exit;
}

// External grab from $param (you can extend this logic as needed)
$external_data = [];
foreach ($_GET as $key => $value) {
    $external_data["\$$key"] = $value;
}

// Final destination template with # placeholders
// Example: https://final.com/page?e=#EMAIL#
$final_template = "https://finaldestination.com/landing?e=#EMAIL#";

// Replace #EMAIL# with actual decoded email
$final_url = str_replace('#EMAIL#', urlencode($email), $final_template);

// Output redirection header
header("Location: $final_url");
exit;