import json from decimal import Decimal from django.http import JsonResponse from django.shortcuts import render, redirect, get_object_or_404 from django.views.decorators.csrf import csrf_exempt from django.views.decorators.http import require_POST from .models import Cart, CartItem, Order, PendingCheckout from vendors.models import VendorProduct def _compute_delivery_breakdown(items): """ Compute per-vendor delivery and cart totals for a unified cart. """ grouped = {} for item in items: vendor = item.product.vendor bucket = grouped.setdefault( vendor.id, { "vendor_id": str(vendor.id), "vendor_name": vendor.store_name, "vendor": vendor, "items_subtotal": Decimal("0"), "delivery_fee": Decimal("0"), "vendor_total": Decimal("0"), }, ) bucket["items_subtotal"] += item.subtotal rows = [] items_subtotal = Decimal("0") delivery_total = Decimal("0") for _, row in grouped.items(): items_subtotal += row["items_subtotal"] vendor = row.get("vendor") fee = Decimal("0") if vendor: fee = vendor.delivery_fee or Decimal("0") threshold = vendor.free_delivery_threshold if threshold is not None and row["items_subtotal"] >= threshold: fee = Decimal("0") row["delivery_fee"] = fee row["vendor_total"] = row["items_subtotal"] + fee delivery_total += fee row.pop("vendor", None) rows.append(row) grand_total = items_subtotal + delivery_total return rows, items_subtotal, delivery_total, grand_total def _get_or_create_cart(request): """Resolve or create a Cart for the current session/user.""" if not request.session.session_key: request.session.create() session_key = request.session.session_key or "" if request.user.is_authenticated: cart = Cart.objects.filter(user=request.user).first() if not cart: cart = Cart.objects.create(user=request.user, session_key=session_key) return cart cart = Cart.objects.filter(session_key=session_key, user__isnull=True).first() if not cart: cart = Cart.objects.create(session_key=session_key) return cart @csrf_exempt @require_POST def cart_add(request): try: body = json.loads(request.body) except json.JSONDecodeError: return JsonResponse({"error": "Invalid JSON"}, status=400) product_id = body.get("product_id") quantity = int(body.get("quantity", 1)) if not product_id: return JsonResponse({"error": "Product ID required"}, status=400) try: product = VendorProduct.objects.get(id=product_id, in_stock=True) except VendorProduct.DoesNotExist: return JsonResponse({"error": "Product not found or out of stock"}, status=404) # Check available stock before adding if product.quantity < quantity: return JsonResponse({ "error": f"Only {product.quantity} unit(s) available" }, status=400) cart = _get_or_create_cart(request) item, created = CartItem.objects.get_or_create( cart=cart, product=product, defaults={"quantity": quantity}, ) if not created: # Check total quantity won't exceed stock new_qty = item.quantity + quantity if new_qty > product.quantity: return JsonResponse({ "error": f"Only {product.quantity} unit(s) available (you already have {item.quantity} in cart)" }, status=400) item.quantity = new_qty item.save(update_fields=["quantity"]) return JsonResponse({ "success": True, "cart_count": cart.item_count, "message": f"{product.name} added to cart", }) @csrf_exempt @require_POST def cart_remove(request): try: body = json.loads(request.body) except json.JSONDecodeError: return JsonResponse({"error": "Invalid JSON"}, status=400) item_id = body.get("item_id") cart = _get_or_create_cart(request) try: item = CartItem.objects.get(id=item_id, cart=cart) item.delete() except CartItem.DoesNotExist: pass return JsonResponse({"success": True, "cart_count": cart.item_count}) @csrf_exempt @require_POST def cart_update(request): try: body = json.loads(request.body) except json.JSONDecodeError: return JsonResponse({"error": "Invalid JSON"}, status=400) item_id = body.get("item_id") quantity = int(body.get("quantity", 1)) cart = _get_or_create_cart(request) try: item = CartItem.objects.get(id=item_id, cart=cart) if quantity <= 0: item.delete() else: # Don't allow setting qty above available stock if quantity > item.product.quantity: quantity = item.product.quantity if quantity <= 0: item.delete() else: item.quantity = quantity item.save(update_fields=["quantity"]) except CartItem.DoesNotExist: pass return JsonResponse({"success": True, "cart_count": cart.item_count}) def cart_view(request): cart = _get_or_create_cart(request) items = cart.items.select_related("product", "product__vendor").prefetch_related("product__images").all() vendor_breakdown, items_subtotal, delivery_total, grand_total = _compute_delivery_breakdown(items) if request.headers.get("X-Requested-With") == "XMLHttpRequest": items_data = [] for item in items: items_data.append({ "id": item.id, "product_id": item.product.id, "name": item.product.name, "price": float(item.product.price), "currency": item.product.currency, "image_url": item.product.primary_image_url, "store_name": item.product.vendor.store_name, "quantity": item.quantity, "subtotal": float(item.subtotal), "in_stock": item.product.in_stock, "available_qty": item.product.quantity, }) return JsonResponse({ "items": items_data, "items_subtotal": float(items_subtotal), "delivery_total": float(delivery_total), "total": float(grand_total), "count": cart.item_count, "vendor_breakdown": [ { "vendor_id": row["vendor_id"], "vendor_name": row["vendor_name"], "items_subtotal": float(row["items_subtotal"]), "delivery_fee": float(row["delivery_fee"]), "vendor_total": float(row["vendor_total"]), } for row in vendor_breakdown ], }) return render(request, "cart/cart.html", { "cart": cart, "items": items, "vendor_breakdown": vendor_breakdown, "items_subtotal": items_subtotal, "delivery_total": delivery_total, "grand_total": grand_total, }) def cart_count(request): cart = _get_or_create_cart(request) return JsonResponse({"count": cart.item_count}) def checkout(request): """ Pay-first checkout: buyer pays via Paystack before any Order or VendorOrder exists. Order, vendor splits, escrows, and vendor notifications are created when payment verifies. """ cart = _get_or_create_cart(request) # WhatsApp session bridge: if wa_session param present, merge WA cart into this cart wa_session_key = request.GET.get("wa_session", "").strip() if wa_session_key: from django.core.cache import cache wa_items = cache.get(f"wa_session:{wa_session_key.replace('wa:', '')}:cart", []) for item in wa_items: if item.get("vendor_id"): try: from vendors.models import VendorProduct product = VendorProduct.objects.get(id=item["product_id"], in_stock=True) CartItem.objects.update_or_create( cart=cart, product=product, defaults={"quantity": item["quantity"]}, ) except VendorProduct.DoesNotExist: pass if wa_items: from whatsapp.session import clear_cart as wa_clear_cart wa_clear_cart(wa_session_key.replace("wa:", "")) items = cart.items.select_related("product", "product__vendor").all() vendor_breakdown, items_subtotal, delivery_total, grand_total = _compute_delivery_breakdown(items) if not items.exists(): return redirect("cart:view") if request.method == "POST": customer_name = request.POST.get("customer_name", "").strip() customer_email = request.POST.get("customer_email", "").strip() customer_phone = request.POST.get("customer_phone", "").strip() delivery_address = request.POST.get("delivery_address", "").strip() errors = [] if not customer_name: errors.append("Name is required.") if not customer_email: errors.append("Email is required.") if not delivery_address: errors.append("Delivery address is required.") if not customer_phone: errors.append("Phone number is required — we send delivery confirmation via SMS.") # Check stock availability for all items stock_errors = [] for item in items: if not item.product.in_stock: stock_errors.append( f"{item.product.name} is no longer in stock and cannot be purchased." ) elif item.quantity > item.product.quantity: stock_errors.append( f"{item.product.name}: only {item.product.quantity} unit(s) available " f"but you have {item.quantity} in your cart." ) errors.extend(stock_errors) if errors: return render(request, "cart/checkout.html", { "cart": cart, "items": items, "vendor_breakdown": vendor_breakdown, "items_subtotal": items_subtotal, "delivery_total": delivery_total, "grand_total": grand_total, "errors": errors, "form_data": request.POST, }) lines = [] for item in items: lines.append({ "product_id": str(item.product_id), "quantity": item.quantity, "product_price": str(item.product.price), "product_name": item.product.name, "currency": item.product.currency, "vendor_id": str(item.product.vendor_id), "line_subtotal": str(item.subtotal), }) pending = PendingCheckout.objects.create( cart=cart, user=request.user if request.user.is_authenticated else None, session_key=request.session.session_key or "", customer_name=customer_name, customer_email=customer_email, customer_phone=customer_phone, delivery_address=delivery_address, items_subtotal=items_subtotal, delivery_total=delivery_total, total_amount=grand_total, lines=lines, vendor_breakdown=[ { "vendor_id": row["vendor_id"], "items_subtotal": str(row["items_subtotal"]), "delivery_fee": str(row["delivery_fee"]), "vendor_total": str(row["vendor_total"]), } for row in vendor_breakdown ], ) try: from escrow.services.escrow_service import initiate_escrow_payment_pending ps_data = initiate_escrow_payment_pending(pending, request) return redirect(ps_data["authorization_url"]) except Exception as exc: import logging logging.getLogger(__name__).error("Escrow payment init failed: %s", exc) pending.delete() errors = [ "We could not start payment. Please try again in a moment or contact support.", ] return render(request, "cart/checkout.html", { "cart": cart, "items": items, "vendor_breakdown": vendor_breakdown, "items_subtotal": items_subtotal, "delivery_total": delivery_total, "grand_total": grand_total, "errors": errors, "form_data": request.POST, }) # GET: check for any out-of-stock items and warn the user stock_warnings = [] for item in items: if not item.product.in_stock: stock_warnings.append(f"{item.product.name} is out of stock.") elif item.quantity > item.product.quantity: stock_warnings.append( f"{item.product.name}: only {item.product.quantity} unit(s) available." ) return render(request, "cart/checkout.html", { "cart": cart, "items": items, "vendor_breakdown": vendor_breakdown, "items_subtotal": items_subtotal, "delivery_total": delivery_total, "grand_total": grand_total, "stock_warnings": stock_warnings, }) def order_confirmation(request, order_id): """Fallback confirmation page (shown if Paystack unavailable).""" order = get_object_or_404(Order, id=order_id) items = order.items.select_related("vendor", "product").all() vendor_orders = order.vendor_orders.select_related("vendor").all() return render(request, "cart/order_confirmation.html", { "order": order, "items": items, "vendor_orders": vendor_orders, })