"""Passenger checkout + eSewa callbacks (FR-13/FR-14, BR-2). Flow: book -> Booking(PENDING_PAYMENT, 15-min deadline) -> /checkout// auto-submits the signed form to eSewa -> eSewa redirects to /payments/esewa/ success|failure. Every callback is logged append-only (PaymentWebhookLog), signature-verified, and idempotent per transaction_uuid. """ from datetime import timedelta from django.contrib import messages from django.shortcuts import redirect, render from django.utils import timezone from .models import Booking, Payment, PaymentWebhookLog from .payments import (build_esewa_form, check_status, decode_callback, esewa_form_url, verify_callback_signature) from .realtime import broadcast_seat_update, notify_admins, notify_operator from .views import current_user, log_audit, role_required PAYMENT_WINDOW_MINUTES = 15 # BR-2 def expire_stale_bookings(): """Lazy sweep: PENDING_PAYMENT bookings past their deadline become EXPIRED and their seats go back on sale. Called from the hot passenger paths, so no background worker is required.""" now = timezone.now() stale = Booking.objects.filter(booking_status='PENDING_PAYMENT', payment_deadline__lt=now).select_related('schedule') for b in stale: seat_numbers = list(b.booking_seats.values_list('seat__seat_number', flat=True)) b.booking_status = 'EXPIRED' b.cancelled_by = 'SYSTEM' b.cancel_reason = 'Payment window expired' b.cancelled_at = now b.save(update_fields=['booking_status', 'cancelled_by', 'cancel_reason', 'cancelled_at']) Payment.objects.filter(booking=b, status__in=['INITIATED', 'PENDING']).update(status='FAILED') if seat_numbers: broadcast_seat_update(b.schedule_id, seat_numbers, 'AVAILABLE') def _next_transaction_uuid(booking): n = Payment.objects.filter(booking=booking).count() + 1 return f"{booking.booking_code}-A{n}" # alphanumeric + hyphen only, unique per attempt @role_required('PASSENGER') def checkout(request, booking_id): expire_stale_bookings() user = current_user(request) booking = Booking.objects.select_related( 'schedule__bus', 'schedule__route__source_city', 'schedule__route__destination_city' ).filter(id=booking_id, user=user).first() if booking is None: messages.error(request, 'Booking not found.') return redirect('my_bookings') if booking.booking_status == 'CONFIRMED': messages.success(request, f'Booking {booking.booking_code} is already paid and confirmed.') return redirect('my_bookings') if booking.booking_status != 'PENDING_PAYMENT': messages.error(request, f'This booking is {booking.booking_status} and cannot be paid.') return redirect('my_bookings') remaining = int((booking.payment_deadline - timezone.now()).total_seconds()) payment = Payment.objects.create( booking=booking, gateway='ESEWA', transaction_uuid=_next_transaction_uuid(booking), amount=booking.total_amount, status='INITIATED', ) form_fields = build_esewa_form( payment, success_url=request.build_absolute_uri('/payments/esewa/success/'), failure_url=request.build_absolute_uri('/payments/esewa/failure/'), ) seats = list(booking.booking_seats.select_related('seat').all()) return render(request, 'checkout.html', { 'booking': booking, 'payment': payment, 'seats': seats, 'form_fields': form_fields, 'esewa_url': esewa_form_url(), 'remaining_seconds': max(remaining, 0), }) def _confirm_payment(payment, ref_id, raw): """Idempotently mark a payment COMPLETE and its booking CONFIRMED.""" booking = payment.booking payment.status = 'COMPLETE' payment.ref_id = ref_id or payment.ref_id payment.raw_response = raw payment.save(update_fields=['status', 'ref_id', 'raw_response']) if booking.booking_status == 'PENDING_PAYMENT': booking.booking_status = 'CONFIRMED' booking.save(update_fields=['booking_status']) seat_numbers = list(booking.booking_seats.values_list('seat__seat_number', flat=True)) if seat_numbers: broadcast_seat_update(booking.schedule_id, seat_numbers, 'BOOKED') notify_operator(booking.schedule.bus.operator_id, 'new_booking', { 'booking_code': booking.booking_code, 'seats': booking.seats_count, 'total': float(booking.total_amount), }) notify_admins('payment_complete', { 'booking_code': booking.booking_code, 'total': float(booking.total_amount), }) from .views import log_activity log_activity(booking.user, 'PASSENGER', 'PAYMENT_COMPLETED', f'{booking.booking_code} - Rs.{booking.total_amount} via eSewa', amount=booking.total_amount) log_activity(booking.schedule.bus.operator.user, 'OPERATOR', 'REVENUE_EARNED', f'{booking.booking_code} - Rs.{booking.operator_earning} earned ' f'(Rs.{booking.commission_amount} commission)', amount=booking.operator_earning) def esewa_success(request): """eSewa redirects here with ?data= after payment.""" data_b64 = request.GET.get('data', '') decoded = decode_callback(data_b64) payment = None if decoded: payment = Payment.objects.select_related( 'booking__schedule__bus').filter(transaction_uuid=decoded.get('transaction_uuid')).first() sig_ok = bool(decoded) and verify_callback_signature(decoded) PaymentWebhookLog.objects.create( payment=payment, transaction_uuid=(decoded or {}).get('transaction_uuid', ''), raw_payload=data_b64 or '(empty)', signature_valid=sig_ok, ) if payment is None: return render(request, 'payment_result.html', {'success': False, 'title': 'Payment could not be matched', 'detail': 'We could not match this payment to a booking. If money was ' 'deducted, it will be verified automatically - contact support ' 'with your eSewa statement.'}) if payment.status == 'COMPLETE': # duplicate / replayed callback - idempotent return render(request, 'payment_result.html', {'success': True, 'booking': payment.booking, 'payment': payment, 'title': 'Payment already confirmed'}) status = (decoded or {}).get('status', '') if sig_ok and status == 'COMPLETE': _confirm_payment(payment, (decoded or {}).get('transaction_code'), data_b64) return render(request, 'payment_result.html', {'success': True, 'booking': payment.booking, 'payment': payment, 'title': 'Payment successful!'}) # Signature failed or status unclear -> ask eSewa directly (authoritative) enquiry = check_status(payment) if enquiry: PaymentWebhookLog.objects.create( payment=payment, transaction_uuid=payment.transaction_uuid, raw_payload=f'status-check: {enquiry}', signature_valid=True, ) if enquiry and enquiry.get('status') == 'COMPLETE': _confirm_payment(payment, enquiry.get('ref_id'), str(enquiry)) return render(request, 'payment_result.html', {'success': True, 'booking': payment.booking, 'payment': payment, 'title': 'Payment successful!'}) payment.status = 'AMBIGUOUS' if enquiry is None else enquiry.get('status', 'FAILED') if payment.status not in dict(Payment.STATUS_CHOICES): payment.status = 'FAILED' payment.raw_response = data_b64 payment.save(update_fields=['status', 'raw_response']) return render(request, 'payment_result.html', {'success': False, 'booking': payment.booking, 'payment': payment, 'title': 'Payment not verified', 'detail': 'The payment response could not be verified. If money was deducted, ' 'use "Complete payment" on My Bookings to retry, or contact support.'}) def esewa_failure(request): """eSewa sends the user here on failed/cancelled payment. The booking stays PENDING_PAYMENT until its deadline so the passenger can retry.""" data_b64 = request.GET.get('data', '') decoded = decode_callback(data_b64) payment = None if decoded and decoded.get('transaction_uuid'): payment = Payment.objects.filter(transaction_uuid=decoded['transaction_uuid']).first() PaymentWebhookLog.objects.create( payment=payment, transaction_uuid=(decoded or {}).get('transaction_uuid', ''), raw_payload=data_b64 or '(no data param)', signature_valid=bool(decoded) and verify_callback_signature(decoded), ) if payment and payment.status in ('INITIATED', 'PENDING'): payment.status = 'CANCELED' payment.raw_response = data_b64 payment.save(update_fields=['status', 'raw_response']) booking = payment.booking if payment else None return render(request, 'payment_result.html', {'success': False, 'booking': booking, 'payment': payment, 'title': 'Payment cancelled', 'detail': 'No money was taken. Your seats are held until the payment window ' 'ends - you can retry from My Bookings.'})