Fallback to budgets when no expenses

app/smart_recommendation.py

@@ -40,19 +40,29 @@ class SmartBudgetRecommender:
         end_date = datetime(year, month, 1) - timedelta(days=1)
         start_date = end_date - timedelta(days=180)  # ~6 months
         
-        expenses = list(self.db.expenses.find({
-            "user_id": user_id,
-            "date": {"$gte": start_date, "$lte": end_date},
-            "type": "expense"
-        }))
-        
-        if not expenses:
-            return []
-        
-        # Group expenses by category and calculate monthly averages
-        category_data = self._calculate_category_statistics(expenses, start_date, end_date)
+        expenses = list(
+            self.db.expenses.find(
+                {
+                    "user_id": user_id,
+                    "date": {"$gte": start_date, "$lte": end_date},
+                    "type": "expense",
+                }
+            )
+        )
+
+        recommendations: List[BudgetRecommendation] = []
+
+        if expenses:
+            # Group expenses by category and calculate monthly averages
+            category_data = self._calculate_category_statistics(
+                expenses, start_date, end_date
+            )
+        else:
+            # No expenses found: fallback to existing budgets for this period
+            category_data = self._get_category_stats_from_budgets(user_id, month, year)
+            if not category_data:
+                return []
         
-        recommendations = []
         for category, data in category_data.items():
             avg_expense = data["average_monthly"]
             confidence = self._calculate_confidence(data)
@@ -235,6 +245,53 @@ class SmartBudgetRecommender:
         result.sort(key=lambda x: x.average_monthly_expense, reverse=True)
         return result
 
+    def _get_category_stats_from_budgets(
+        self, user_id: str, month: int, year: int
+    ) -> Dict:
+        """
+        Fallback source when there are no expenses:
+        use existing budgets for the requested month/year as the 'average' spend.
+        """
+        budgets = list(
+            self.db.budgets.find(
+                {
+                    "user_id": user_id,
+                    "period": {"$in": ["monthly", "MONTHLY"]},
+                    "start_date": {
+                        "$lte": datetime(year, month, 28)
+                    },  # loosely within month
+                }
+            )
+        )
+
+        if not budgets:
+            return {}
+
+        result: Dict[str, Dict] = {}
+        for b in budgets:
+            category = b.get("category", "Uncategorized")
+            amount = float(b.get("amount", 0))
+            if category not in result:
+                result[category] = {
+                    "average_monthly": amount,
+                    "total": amount,
+                    "count": 1,
+                    "months_analyzed": 1,
+                    "std_dev": 0.0,
+                    "monthly_values": [amount],
+                }
+            else:
+                # If multiple budgets per category, average them
+                result[category]["total"] += amount
+                result[category]["count"] += 1
+                result[category]["months_analyzed"] = result[category]["count"]
+                result[category]["average_monthly"] = (
+                    result[category]["total"] / result[category]["count"]
+                )
+                result[category]["monthly_values"].append(amount)
+
+        return result
+
     def _get_ai_recommendation(self, category: str, data: Dict, avg_expense: float):
         """Use OpenAI to refine the budget recommendation."""
         if not OPENAI_API_KEY: