// 5. PROCESS REQUESTS
// ---------------------------------------------------

// A. HANDLE DATA UPLOAD (POST)
// (This part stays the same, keep your existing POST logic here)
if ($requestMethod == 'POST' && !empty($postBody)) {
    // ... [Keep your existing POST insert code here] ...
    // ...
    // ...
    file_put_contents($logFile, "-> SAVED $count RECORDS. Sending OK.\n", FILE_APPEND);
    echo "OK";
    exit;
}

// B. HANDLE HEAD REQUESTS (The Fix)
if ($requestMethod == 'HEAD') {
    // CRITICAL: We return 405 to tell the device "Stop Pinging, Send Data!"
    // This forces the device to switch to GET or POST immediately.
    http_response_code(405); 
    header("Allow: POST, GET");
    exit;
}

// C. HANDLE HANDSHAKE (GET)
// Only send config when device uses GET
if ($requestMethod == 'GET') {
    
    file_put_contents($logFile, "-> SENDING HANDSHAKE CONFIG (GET).\n", FILE_APPEND);

    header("Content-Type: text/plain");
    echo "GET OPTION FROM: " . $sn . "\n";
    echo "ATTLOGStamp=0\n";
    echo "OPERLOGStamp=0\n";
    echo "ATTPHOTOStamp=0\n";
    echo "ErrorDelay=30\n";
    echo "Delay=10\n";
    echo "TransTimes=00:00;14:05\n";
    echo "TransInterval=1\n";
    echo "TransFlag=1111000000\n";
    echo "TimeZone=7\n";
    echo "Realtime=1\n";
    echo "Encrypt=0\n";
    
    exit;
}

echo "OK";
?>