From aeb99c65cc7ac7fc1fe7be1ae4a092aba2cf6ddc Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 4 Mar 2026 09:50:23 +0000
Subject: [PATCH] WIP

---
 rust/Cargo.toml        |   2 +-
 rust/src/events/mod.rs | 116 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+), 1 deletion(-)

diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index bca2f6ed70..0102e6eda9 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -43,7 +43,7 @@ pyo3-log = "0.13.1"
 pythonize = "0.27.0"
 regex = "1.6.0"
 sha2 = "0.10.8"
-serde = { version = "1.0.144", features = ["derive"] }
+serde = { version = "1.0.144", features = ["derive", "rc"] }
 serde_json = "1.0.85"
 ulid = "1.1.2"
 icu_segmenter = "2.0.0"
diff --git a/rust/src/events/mod.rs b/rust/src/events/mod.rs
index 834e67f461..fdc9784201 100644
--- a/rust/src/events/mod.rs
+++ b/rust/src/events/mod.rs
@@ -29,6 +29,7 @@ use pyo3::{
     wrap_pyfunction, Bound, IntoPyObject, PyAny, PyResult, Python,
 };
 use pythonize::{depythonize, pythonize};
+use serde::{Deserialize, Serialize};
 
 pub mod filter;
 mod internal_metadata;
@@ -38,6 +39,7 @@ pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()>
     let child_module = PyModule::new(py, "events")?;
     child_module.add_class::<internal_metadata::EventInternalMetadata>()?;
     child_module.add_class::<JsonObject>()?;
+    child_module.add_class::<Event>()?;
     child_module.add_function(wrap_pyfunction!(filter::event_visible_to_server_py, m)?)?;
 
     m.add_submodule(&child_module)?;
@@ -71,8 +73,10 @@ struct EventInner {
     signatures: HashMap<Box<str>, HashMap<Box<str>, Box<str>>>,
 }
 
+#[derive(Serialize, Deserialize)]
 #[pyclass(mapping)]
 #[derive(Clone)]
+#[serde(transparent)]
 struct JsonObject {
     object: Arc<HashMap<Box<str>, serde_json::Value>>,
 }
@@ -101,3 +105,115 @@ impl JsonObject {
         Ok(Some(pythonize(py, value)?))
     }
 }
+
+#[derive(Serialize, Deserialize)]
+#[pyclass]
+struct EventCommonFields {
+    #[pyo3(get)]
+    content: JsonObject,
+    #[pyo3(get)]
+    depth: i64,
+    hashes: HashMap<String, String>,
+    #[pyo3(get)]
+    origin_server_ts: i64,
+    #[pyo3(get)]
+    sender: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[pyo3(get)]
+    state_key: Option<String>,
+    #[serde(rename = "type")]
+    #[pyo3(get, name = "type")]
+    type_: String,
+
+    unsigned: JsonObject,
+    signatures: HashMap<Box<str>, HashMap<Box<str>, Box<str>>>,
+
+    #[serde(flatten)]
+    other_fields: HashMap<String, serde_json::Value>,
+}
+
+#[pyclass]
+struct Event {
+    inner: EventFormatEnum,
+}
+
+#[pymethods]
+impl Event {
+    #[new]
+    fn new<'a, 'py>(format: u8, event_dict: &'a Bound<'py, PyAny>) -> PyResult<Self> {
+        if format != 3 {
+            return Err(PyKeyError::new_err(format!(
+                "Unsupported event format version: {}",
+                format
+            )));
+        }
+
+        let event_format_v3: EventFormatV3Container = depythonize(event_dict)?;
+        Ok(Self {
+            inner: EventFormatEnum::V3(event_format_v3),
+        })
+    }
+
+    #[getter]
+    fn room_id(&self) -> Option<&str> {
+        match &self.inner {
+            EventFormatEnum::V3(format) => format.specific_fields.room_id.as_deref(),
+            // ...
+        }
+    }
+
+    fn get_pdu_json<'py>(&self, py: Python<'py>) -> PyResult<Bound<'py, PyAny>> {
+        match &self.inner {
+            EventFormatEnum::V3(format) => Ok(pythonize(py, format)?),
+            // ...
+        }
+    }
+}
+
+enum EventFormatEnum {
+    V3(EventFormatV3Container),
+    // ...
+}
+
+#[derive(Serialize, Deserialize)]
+struct EventFormatV3 {
+    auth_events: Vec<String>,
+    prev_events: Vec<String>,
+    room_id: Option<String>,
+}
+
+#[derive(Serialize, Deserialize)]
+struct EventFormatV3Container {
+    #[serde(flatten)]
+    specific_fields: EventFormatV3,
+    #[serde(flatten)]
+    common_fields: EventCommonFields,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_basic_v3_roundtrip() {
+        let json = r#"{"auth_events":[],"prev_events":[],"type":"m.room.create","sender":"@anon-20260225_142731-20:localhost:8800","content":{"room_version":"10","creator":"@anon-20260225_142731-20:localhost:8800"},"depth":1,"room_id":"!qVoJSympOqdUQRUfiC:localhost:8800","state_key":"","origin_server_ts":1772029657149,"hashes":{"sha256":"RIDkn4CrExGMOfRZlHl//1weAro5QC/q2D76YcyAUqk"},"signatures":{"localhost:8800":{"ed25519:a_GMSl":"GU7WmvI2Kd5kLrXKrWpRbUfEiVKGgH0sxQNEpBMMvgF3QhHN25AubVMmIClht5r/c+Iihb1xsq1j5Sw+RGfiDg"}},"unsigned":{"age_ts":1772029657149}}"#;
+        let event_value: serde_json::Value = serde_json::from_str(json).unwrap();
+
+        let event: EventFormatV3Container = serde_json::from_str(json).unwrap();
+        let parsed_value = serde_json::to_value(&event).unwrap();
+
+        assert_eq!(event.common_fields.type_, "m.room.create".to_string());
+
+        assert_eq!(
+            event.specific_fields.room_id,
+            Some("!qVoJSympOqdUQRUfiC:localhost:8800".to_string())
+        );
+
+        assert_eq!(
+            event.common_fields.other_fields.get("auth_events").unwrap(),
+            &serde_json::Value::Array(vec![])
+        );
+
+        assert_eq!(event_value, parsed_value);
+    }
+}