<?php
declare(strict_types=1);

function throttle_webhook_channel(string $channel, int $minIntervalSeconds): void
{
    if ($channel === '' || $minIntervalSeconds <= 0) {
        return;
    }

    $sanitizedChannel = preg_replace('/[^a-z0-9_-]+/i', '_', $channel) ?? 'default';
    $lockPath = sys_get_temp_dir() . '/erp_naurua_webhook_throttle_' . $sanitizedChannel . '.lock';

    $handle = fopen($lockPath, 'c+');
    if ($handle === false) {
        return;
    }

    try {
        if (!flock($handle, LOCK_EX)) {
            return;
        }

        rewind($handle);
        $raw = stream_get_contents($handle);
        $lastSentAt = is_string($raw) ? (float) trim($raw) : 0.0;
        $now = microtime(true);
        $waitSeconds = ($lastSentAt + $minIntervalSeconds) - $now;

        if ($waitSeconds > 0) {
            usleep((int) ceil($waitSeconds * 1000000));
        }

        $sentAt = microtime(true);
        rewind($handle);
        ftruncate($handle, 0);
        fwrite($handle, sprintf('%.6f', $sentAt));
        fflush($handle);
    } finally {
        flock($handle, LOCK_UN);
        fclose($handle);
    }
}