add endpoint for retrieving fraud status of existing an transaction

src/main.py

@@ -32,7 +32,7 @@ from src.service.logging_service import setup_logging
 from src.service.notification_service import send_notification
 from src.repository.common import get_session
 from src.repository.fraud_details_repo import insert_fraud
-from src.repository.transaction_repo import insert_transaction
+from src.repository.transaction_repo import insert_transaction, fetch_transaction
 
 # ------------------------------------------------------------------------------
 # Configure logging
@@ -99,7 +99,48 @@ class TransactionProcessingOutput(BaseModel):
                 "fraud_score": 0.85
             }
         })
+    
+@app.get("/transaction/get_fraud_status/{transaction_number}",
+          tags=["transaction"],
+          description="Get the fraud status of a transaction",
+          response_model=TransactionProcessingOutput,
+          )
+async def get_fraud_status(
+    transaction_number: str,
+    db: Annotated[Session, Depends(provide_connection)]
+):
+    """
+    Get the fraud status of a transaction
+    """
+    # Check if the transaction exists in the database
+    try:
+        transaction = fetch_transaction(
+            db=db,
+            transaction_number=transaction_number
+        )
+    except ValueError as e:
+        logger.error(e)
+        raise HTTPException(
+            status_code=HTTP_422_UNPROCESSABLE_ENTITY,
+            detail=f"Transaction {transaction_number} does not exist"
+        )
+    except Exception as e:
+        logger.error(e)
+        raise HTTPException(
+            status_code=HTTP_500_INTERNAL_SERVER_ERROR,
+            detail="An error occurred while fetching the transaction. See logs for details."
+        )
+
+    # Check if the transaction is fraudulent
+    is_fraud = transaction.is_fraud
+    fraud_score = transaction.fraud_score
 
+    return {
+        'is_fraud': is_fraud,
+        'fraud_score': fraud_score
+    }
+
+# ------------------------------------------------------------------------------
 @app.post("/transaction/process",
           tags=["transaction"],
           description="Process a transaction",
@@ -127,11 +168,11 @@ async def process_transaction(
     try:
         # Insert every single transaction into the database
         transaction = insert_transaction(db, transaction)
-    except UniqueViolation as e:
-        logger.error(e)
-        raise HTTPException(
-            status_code=HTTP_422_UNPROCESSABLE_ENTITY,
-            detail=f"Transaction {transaction.transaction_number} already exists"
+    except UniqueViolation:
+        logger.warning("Transaction already exists in the database - retrieving it")
+        return get_fraud_status(
+            transaction_number=transaction.transaction_number,
+            db=db
         )
     except IntegrityError as e:
         logger.error(e)