<?php
error_reporting(0);
header("Content-Type: application/json");

$dir = "fast_frames/";
if (!is_dir($dir)) mkdir($dir, 0755, true);

$id = $_GET['id'] ?? null;
if (!$id) { echo json_encode(["error" => "no id"]); exit; }
$id    = preg_replace('/[^a-z0-9]/i', '', $id);
$frame = $dir . "f_{$id}.dat";
$meta  = $dir . "m_{$id}.json";

// ── CLIENTE sube frame ──
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $body = file_get_contents("php://input");
    if (!$body) { echo json_encode(["error" => "empty"]); exit; }

    $ts = microtime(true);
    file_put_contents($frame, $body,  LOCK_EX);
    file_put_contents($meta,  json_encode(["ts" => $ts, "size" => strlen($body)]), LOCK_EX);
    echo json_encode(["status" => "ok", "ts" => $ts]);
    exit;
}

// ── PANEL descarga frame (long-poll: espera hasta 1s si no hay frame nuevo) ──
$since = floatval($_GET['since'] ?? 0);
$waited = 0;

while ($waited < 1000) {
    if (file_exists($meta)) {
        $info = json_decode(file_get_contents($meta), true);
        $ts   = floatval($info['ts'] ?? 0);
        if ($ts > $since) {
            $b64 = base64_encode(file_get_contents($frame));
            echo json_encode(["ts" => $ts, "b64" => $b64]);
            exit;
        }
    }
    usleep(30000);   // 30ms
    $waited += 30;
}

// Timeout — no hay frame nuevo
echo json_encode(["ts" => $since, "b64" => null]);