<?php
// PHP 8.1+, PDO SQLite. Serve this endpoint using HTTPS.
function reply(int $code, string $text): never { http_response_code($code); exit($text); }
if ($_SERVER['REQUEST_METHOD'] !== 'POST') reply(405, 'POST required');
$secret = getenv('BLUAUTO_WEBHOOK_SECRET');
if (!$secret) reply(503, 'Secret not configured');
$raw = file_get_contents('php://input', false, null, 0, 65537);
if (strlen($raw) > 65536) reply(413, 'Too large');
$ts = $_SERVER['HTTP_X_DIDBAN_TIMESTAMP'] ?? '';
$sig = $_SERVER['HTTP_X_DIDBAN_SIGNATURE'] ?? '';
if (!preg_match('/^\d{1,12}$/D', $ts) || abs(time()-(int)$ts)>300) reply(401, 'Expired signature');
if (!hash_equals('v1='.hash_hmac('sha256', $ts.'.'.$raw, $secret), $sig)) reply(401, 'Invalid signature');
try { $e=json_decode($raw,true,32,JSON_THROW_ON_ERROR); } catch (Throwable $error) { reply(400,'Invalid JSON'); }
$d=$e['data']??[];$event=$e['event_id']??null;
if (is_string($event)&&strlen($event)>0&&strlen($event)<=100&&$event===($_SERVER['HTTP_X_DIDBAN_EVENT_ID']??'')&&($e['type']??'')==='webhook.test'&&($d['mode']??'')==='test'&&($d['paid']??null)===false) reply(200,'Test acknowledged');
if (!is_string($event)||strlen($event)<1||strlen($event)>100||$event!==($_SERVER['HTTP_X_DIDBAN_EVENT_ID']??'')||($e['type']??'')!=='invoice.paid'||($d['mode']??'')!=='live'||($d['status']??'')!=='PAID'||($d['paid']??false)!==true||!is_string($d['amount_rial']??null)||!preg_match('/^[1-9]\d{0,23}$/D',$d['amount_rial'])) reply(400,'Invalid event');
try {
 $dbPath=getenv('BLUAUTO_WEBHOOK_DB');if(!$dbPath) reply(503,'Set database path outside web root');
 $db=new PDO('sqlite:'.$dbPath);$db->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
 $db->exec('PRAGMA busy_timeout=10000; PRAGMA journal_mode=WAL; CREATE TABLE IF NOT EXISTS orders(order_id TEXT PRIMARY KEY,invoice_id TEXT UNIQUE NOT NULL,amount_rial TEXT NOT NULL,paid INTEGER NOT NULL DEFAULT 0); CREATE TABLE IF NOT EXISTS webhook_receipts(event_id TEXT PRIMARY KEY,invoice_id TEXT NOT NULL); CREATE TABLE IF NOT EXISTS fulfillment_jobs(order_id TEXT PRIMARY KEY,status TEXT NOT NULL DEFAULT 0);');
 $db->exec('BEGIN IMMEDIATE');
 $q=$db->prepare('SELECT invoice_id,amount_rial FROM orders WHERE order_id=?');$q->execute([$d['order_id']??'']);$row=$q->fetch(PDO::FETCH_ASSOC);
 if (!$row||$row['invoice_id']!==($d['id']??'')||$row['amount_rial']!==$d['amount_rial']) { $db->exec('ROLLBACK');reply(409,'Order mismatch'); }
 $q=$db->prepare('SELECT invoice_id FROM webhook_receipts WHERE event_id=?');$q->execute([$event]);$old=$q->fetchColumn();
 if ($old!==false&&$old!==$d['id']) { $db->exec('ROLLBACK');reply(409,'Event conflict'); }
 $db->prepare('INSERT OR IGNORE INTO webhook_receipts VALUES(?,?)')->execute([$event,$d['id']]);
 $db->prepare('UPDATE orders SET paid=1 WHERE order_id=? AND paid=0')->execute([$d['order_id']]);
 $db->prepare('INSERT OR IGNORE INTO fulfillment_jobs(order_id) VALUES(?)')->execute([$d['order_id']]);
 // Add an idempotent fulfillment job here, in this DB transaction.
 $db->exec('COMMIT');reply(200,'OK');
} catch (Throwable $error) { if(isset($db))try{$db->exec('ROLLBACK');}catch(Throwable $ignored){} reply(503,'Retry later'); }