"""bluauto webhook receiver. Put behind an HTTPS reverse proxy; Python 3.10+."""
import os,json,hmac,hashlib,time,sqlite3,re
from http.server import BaseHTTPRequestHandler,ThreadingHTTPServer

def database(path):
    db=sqlite3.connect(path,timeout=10)
    db.execute('PRAGMA journal_mode=WAL')
    db.executescript('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);')
    return db

def receive(raw,headers,path,secret,now=None):
    now=int(time.time()) if now is None else now
    ts=headers.get('X-Didban-Timestamp','');sig=headers.get('X-Didban-Signature','')
    if not secret: return 503,'Webhook secret is not configured'
    if not re.fullmatch(r'\d{1,12}',ts) or abs(now-int(ts))>300: return 401,'Expired signature'
    expected='v1='+hmac.new(secret.encode(),ts.encode()+b'.'+raw,hashlib.sha256).hexdigest()
    if not hmac.compare_digest(expected,sig): return 401,'Invalid signature'
    try:
        e=json.loads(raw);d=e['data'];event=e['event_id']
        if not isinstance(event,str) or not 1<=len(event)<=100 or event!=headers.get('X-Didban-Event-Id'): return 400,'Invalid event'
        if e['type']=='webhook.test' and d.get('mode')=='test' and d.get('paid') is False: return 200,'Test acknowledged'
        if e['type']!='invoice.paid' or d['mode']!='live' or d['status']!='PAID' or d['paid'] is not True: return 400,'Unsupported event'
        if not isinstance(d['amount_rial'],str) or not re.fullmatch(r'[1-9]\d{0,23}',d['amount_rial']): return 400,'Invalid amount'
        db=database(path)
        try:
            db.execute('BEGIN IMMEDIATE')
            row=db.execute('SELECT invoice_id,amount_rial,paid FROM orders WHERE order_id=?',(d['order_id'],)).fetchone()
            if not row or row[0]!=d['id'] or row[1]!=d['amount_rial']: db.rollback();return 409,'Order mismatch'
            old=db.execute('SELECT invoice_id FROM webhook_receipts WHERE event_id=?',(event,)).fetchone()
            if old and old[0]!=d['id']: db.rollback();return 409,'Event conflict'
            db.execute('INSERT OR IGNORE INTO webhook_receipts VALUES(?,?)',(event,d['id']))
            db.execute('UPDATE orders SET paid=1 WHERE order_id=? AND paid=0',(d['order_id'],))
            db.execute('INSERT OR IGNORE INTO fulfillment_jobs(order_id) VALUES(?)',(d['order_id'],))
            # Queue fulfillment inside this transaction using a unique order_id.
            # Do not send goods or call external services before committing.
            db.commit();return 200,'OK'
        finally: db.close()
    except (KeyError,ValueError,TypeError): return 400,'Invalid payload'

class Handler(BaseHTTPRequestHandler):
    def do_POST(self):
        if self.path!='/webhook': self.send_error(404);return
        try: size=int(self.headers.get('Content-Length','0'))
        except ValueError: self.send_error(400);return
        if not 0<size<=65536: self.send_error(413);return
        try: code,text=receive(self.rfile.read(size),self.headers,os.environ.get('BLUAUTO_WEBHOOK_DB','merchant.sqlite'),os.environ.get('BLUAUTO_WEBHOOK_SECRET',''))
        except (sqlite3.Error,OSError): code,text=503,'Retry later'
        self.send_response(code);self.end_headers();self.wfile.write(text.encode())
    def log_message(self,*args): pass
if __name__=='__main__':
    ThreadingHTTPServer(('127.0.0.1',int(os.environ.get('PORT','8088'))),Handler).serve_forever()