Twitter snowflake id timestamp extraction

snowflake-date.php

#!/usr/bin/env php

<?php

/// Takes either the tweet ID only or the full URL to a post.
/// Returns the UTC timestamp.
function extract_tweet_timestamp($input) {
    $twitter_epoch = 1288834974657; // in milliseconds

    // Extract the snowflake id
    if (preg_match('~(twitter\.com|x\.com)/[^/]+/status/([0-9]+)~', $input, $m)) {
        $snowflake = $m[2];
    } elseif (is_numeric($input)) {
        $snowflake = $input;
    } else {
        throw new InvalidArgumentException("Could not extract tweet ID.");
    }

    // Convert input to string to use as bignum
    if (!is_string($snowflake)) {
        $snowflake = (string)$snowflake;
    }

    if (function_exists('bcdiv')) {
        // Get first 41 bits
        $timestamp_ms_part = bcdiv($snowflake, bcpow('2', '22'));
        // Add epoch, get timestamp in ms
        $unix_ms = bcadd($timestamp_ms_part, $twitter_epoch);
        // Get seconds and milliseconds
        $seconds = bcdiv($unix_ms, '1000', 3);
        return $seconds;
    } else {
        // Assume 64-bit PHP_INT_MAX
        $snowflake_int = is_numeric($snowflake) ? (int)$snowflake : 0;
        $timestamp_ms_part = $snowflake_int >> 22;
        $unix_ms = $timestamp_ms_part + $twitter_epoch;
        $seconds = $unix_ms / 1000.0;
        return $seconds;
    }
}

echo date('c', extract_tweet_timestamp($argv[1]));

?>