real middleman: BTCPay payment gate + webhook + Printful adapter + checkout redirect

backend/app/routers/webhooks.py

@@ -0,0 +1,77 @@
+"""BTCPay webhook router — advances orders through the money flow.
+
+POST /api/webhooks/btcpay  (signed by BTCPay)
+
+InvoiceSettled  -> order paid -> place supplier order -> status supplier_order
+InvoiceExpired  -> order cancelled (no payment)
+InvoiceInvalid  -> order cancelled (payment failed)
+"""
+from fastapi import APIRouter, Depends, Header, HTTPException, Request
+from sqlalchemy.orm import Session
+
+from app.database import get_db
+from app.engines.payments import btcpay
+from app.engines.suppliers.base import build_adapter
+from app.models import AuditLog, Order, Supplier
+
+router = APIRouter()
+
+
+def _get_order_by_invoice(db: Session, invoice_id: str):
+    return db.query(Order).filter(Order.btcpay_invoice_id == invoice_id).first()
+
+
+def _place_supplier_order(db: Session, order: Order):
+    """Call the supplier's real create_order and store the reference."""
+    if order.supplier_id is None:
+        order.status = "supplier_order"
+        db.add(AuditLog(actor="webhook", action="no_supplier", entity="order",
+                        entity_id=order.order_number))
+        return
+    supplier = db.query(Supplier).filter(Supplier.id == order.supplier_id).first()
+    if supplier is None:
+        order.status = "supplier_order"
+        return
+    try:
+        adapter = build_adapter(supplier)
+        items = [
+            {"supplier_sku": it.get("sku"), "qty": it.get("qty", 1)}
+            for it in (order.items or [])
+        ]
+        result = adapter.create_order(items)
+        order.supplier_order_ref = str(result.get("ref", ""))
+        order.status = "supplier_order"
+        db.add(AuditLog(actor="webhook", action="supplier_order_placed", entity="order",
+                        entity_id=order.order_number,
+                        detail={"supplier": supplier.name, "ref": order.supplier_order_ref}))
+    except Exception as e:
+        order.status = "paid"  # paid but supplier order failed -> needs manual retry
+        db.add(AuditLog(actor="webhook", action="supplier_order_failed", entity="order",
+                        entity_id=order.order_number, detail={"error": str(e)}))
+
+
+@router.post("/btcpay")
+async def btcpay_webhook(request: Request, db: Session = Depends(get_db)):
+    raw = await request.body()
+    sig = request.headers.get("btcpay-sig", "")
+    if not btcpay.verify_webhook(raw, sig):
+        raise HTTPException(status_code=401, detail="invalid signature")
+
+    payload = await request.json()
+    event_type = payload.get("type")
+    invoice_id = payload.get("invoiceId") or payload.get("id")
+    order = _get_order_by_invoice(db, invoice_id) if invoice_id else None
+    if order is None:
+        return {"ok": True, "matched": False}
+
+    if event_type == "InvoiceSettled":
+        order.status = "paid"
+        _place_supplier_order(db, order)
+    elif event_type in ("InvoiceExpired", "InvoiceInvalid"):
+        order.status = "cancelled"
+    db.commit()
+
+    db.add(AuditLog(actor="btcpay", action=event_type, entity="order",
+                    entity_id=order.order_number, detail={"invoice_id": invoice_id}))
+    db.commit()
+    return {"ok": True, "order": order.order_number, "status": order.status}