Twitter-compliant social media link aggregator

social_media.php

<?php
$social_media = [
    'Instagram' => 'https://www.instagram.com/username/',
    'Facebook' => 'https://www.facebook.com/username/',
];

function request_from_twitter() {
    return !(strpos($_SERVER['HTTP_REFERER'], 'twitter.com')
             || strpos($_SERVER['HTTP_REFERER'], 't.co'));
}

if (request_from_twitter()) {
    $social_media = array();
}

foreach ($social_media as $name => $url) {
    echo '<a href="' . $url . '">' . $name . '</a>';
}