feat: add async support to python binding (#185)

* feat: Add async support to pythong binding

* fix: return NodeResult instead of panic when future missing

bindings/python/src/custom_node.rs

@@ -1,6 +1,7 @@
 use anyhow::anyhow;
 use pyo3::types::PyDict;
-use pyo3::{PyObject, Python};
+use pyo3::{PyObject, PyResult, Python};
+use pyo3_asyncio::tokio::into_future;
 use pythonize::depythonize;
 
 use zen_engine::handler::custom_node_adapter::{CustomNodeAdapter, CustomNodeRequest};
@@ -23,20 +24,40 @@ impl From<Option<PyObject>> for PyCustomNode {
     }
 }
 
+fn extract_custom_node_response(result: PyObject, py: Python<'_>) -> NodeResult {
+    let dict = result.extract::<&PyDict>(py)?;
+    let response: NodeResponse = depythonize(dict)?;
+    Ok(response)
+}
+
 impl CustomNodeAdapter for PyCustomNode {
     async fn handle(&self, request: CustomNodeRequest<'_>) -> NodeResult {
         let Some(callable) = &self.0 else {
             return Err(anyhow!("Custom node handler not provided"));
         };
 
-        let content: NodeResponse = Python::with_gil(|py| {
+        let (future, result) = Python::with_gil(|py| -> PyResult<_> {
             let req = PyNodeRequest::from_request(py, request)?;
             let result = callable.call1(py, (req,))?;
-
-            let dict = result.extract::<&PyDict>(py)?;
-            depythonize(dict)
+            let is_coroutine = result.getattr(py, "__await__").is_ok();
+            if is_coroutine {
+                return Ok((Some(into_future(result.as_ref(py))), None));
+            }
+            Ok((None, Some(extract_custom_node_response(result, py))))
         })?;
 
+        if let Some(result) = result {
+            return result;
+        }
+
+        let result = future
+            .ok_or_else(|| anyhow!("Future or result must be present"))??
+            .await?;
+
+        let content = Python::with_gil(|py| -> PyResult<_> {
+            Ok(extract_custom_node_response(result, py))
+        })??;
+
         Ok(content)
     }
 }