feat(session): integrate actix-web framework with enhanced session management

- Added actix-web and actix-multipart dependencies to Cargo.toml
- Integrated actix-web ResponseError trait for AppError handling
- Migrated session module to use actix-web request lifecycle management
- Enhanced Session struct with request-local state handling capabilities
- Implemented proper HTTP status code mapping for various error types
- Added comprehensive session middleware integration points
- Updated session state persistence and modification tracking logic
- Integrated proper JSON response formatting for error messages
- Added support for session renewal, purge, and unchanged state management

session/session.rs

@@ -1,6 +1,10 @@
 use std::cell::{Ref, RefCell};
+use std::future::{Ready, ready};
+use std::mem;
 use std::rc::Rc;
 
+use actix_web::dev::{Extensions, Payload, ServiceRequest, ServiceResponse};
+use actix_web::{FromRequest, HttpMessage, HttpRequest};
 use serde::Serialize;
 use serde::de::DeserializeOwned;
 use serde_json::{Map, Value};
@@ -10,21 +14,30 @@ use crate::error::AppError;
 
 const SESSION_USER_KEY: &str = "session:user_uid";
 
+/// Request-local session handle.
+///
+/// Clones share the same interior state through request extensions, so changes
+/// made by extractors/handlers can be collected by `SessionMiddleware` at the
+/// end of the request lifecycle.
 #[derive(Clone)]
 pub struct Session(Rc<RefCell<SessionInner>>);
 
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
 pub enum SessionStatus {
+    /// Session state has changed and must be persisted.
     Changed,
+    /// Session and cookie must be deleted. Further mutations are ignored.
     Purged,
+    /// Session key must be regenerated while preserving current state.
     Renewed,
+    /// Session has not been modified during this request.
     #[default]
     Unchanged,
 }
 
 #[derive(Default)]
 struct SessionInner {
-    state: Map<String, Value>,
+    state: SessionState,
     status: SessionStatus,
 }
 
@@ -33,7 +46,7 @@ impl Session {
         Self::default()
     }
 
-    pub fn from_state(state: Map<String, Value>) -> Self {
+    pub fn from_state(state: SessionState) -> Self {
         Self(Rc::new(RefCell::new(SessionInner {
             state,
             status: SessionStatus::Unchanged,
@@ -41,34 +54,36 @@ impl Session {
     }
 
     pub fn get<T: DeserializeOwned>(&self, key: &str) -> Result<Option<T>, AppError> {
-        if let Some(value) = self.0.borrow().state.get(key) {
-            Ok(Some(serde_json::from_value(value.clone())?))
-        } else {
-            Ok(None)
-        }
+        let value = self.0.borrow().state.get(key).cloned();
+        value
+            .map(serde_json::from_value)
+            .transpose()
+            .map_err(AppError::Json)
     }
 
     pub fn contains_key(&self, key: &str) -> bool {
         self.0.borrow().state.contains_key(key)
     }
 
-    pub fn entries(&self) -> Ref<'_, Map<String, Value>> {
+    pub fn entries(&self) -> Ref<'_, SessionState> {
         Ref::map(self.0.borrow(), |inner| &inner.state)
     }
 
     pub fn status(&self) -> SessionStatus {
-        Ref::map(self.0.borrow(), |inner| &inner.status).clone()
+        self.0.borrow().status.clone()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.borrow().state.is_empty()
     }
 
     pub fn insert<T: Serialize>(&self, key: impl Into<String>, value: T) -> Result<(), AppError> {
+        let value = serde_json::to_value(value)?;
         let mut inner = self.0.borrow_mut();
 
         if inner.status != SessionStatus::Purged {
-            if inner.status != SessionStatus::Renewed {
-                inner.status = SessionStatus::Changed;
-            }
-            let val = serde_json::to_value(&value)?;
-            inner.state.insert(key.into(), val);
+            mark_changed(&mut inner.status);
+            inner.state.insert(key.into(), value);
         }
 
         Ok(())
@@ -83,22 +98,20 @@ impl Session {
         F: FnOnce(T) -> T,
     {
         let mut inner = self.0.borrow_mut();
-        let key_str = key.into();
+        let key = key.into();
 
-        if let Some(val) = inner.state.get(&key_str) {
-            if inner.status == SessionStatus::Purged {
-                return Ok(());
-            }
-
-            let value: T = serde_json::from_value(val.clone())?;
-            let updated = serde_json::to_value(updater(value))?;
-
-            if inner.status != SessionStatus::Renewed {
-                inner.status = SessionStatus::Changed;
-            }
-            inner.state.insert(key_str, updated);
+        if inner.status == SessionStatus::Purged {
+            return Ok(());
         }
 
+        let Some(value) = inner.state.get(&key).cloned() else {
+            return Ok(());
+        };
+
+        let value = serde_json::from_value(value)?;
+        let updated = serde_json::to_value(updater(value))?;
+        mark_changed(&mut inner.status);
+        inner.state.insert(key, updated);
         Ok(())
     }
 
@@ -121,14 +134,12 @@ impl Session {
     pub fn remove(&self, key: &str) -> Option<Value> {
         let mut inner = self.0.borrow_mut();
 
-        if inner.status != SessionStatus::Purged {
-            if inner.status != SessionStatus::Renewed {
-                inner.status = SessionStatus::Changed;
-            }
-            return inner.state.remove(key);
+        if inner.status == SessionStatus::Purged {
+            return None;
         }
 
-        None
+        mark_changed(&mut inner.status);
+        inner.state.remove(key)
     }
 
     pub fn remove_as<T: DeserializeOwned>(&self, key: &str) -> Option<Result<T, AppError>> {
@@ -140,9 +151,7 @@ impl Session {
         let mut inner = self.0.borrow_mut();
 
         if inner.status != SessionStatus::Purged {
-            if inner.status != SessionStatus::Renewed {
-                inner.status = SessionStatus::Changed;
-            }
+            mark_changed(&mut inner.status);
             inner.state.clear();
         }
     }
@@ -174,13 +183,45 @@ impl Session {
     }
 
     pub fn take_state(&self) -> SessionState {
-        let mut inner = self.0.borrow_mut();
-        std::mem::take(&mut inner.state)
+        mem::take(&mut self.0.borrow_mut().state)
     }
 
     pub fn mark_unchanged(&self) {
         self.0.borrow_mut().status = SessionStatus::Unchanged;
     }
+
+    pub(crate) fn set_session(req: &mut ServiceRequest, state: SessionState) {
+        let session = Self::get_session(&mut req.extensions_mut());
+        let mut inner = session.0.borrow_mut();
+        inner.state = state;
+        inner.status = SessionStatus::Unchanged;
+    }
+
+    pub(crate) fn get_changes<B>(res: &mut ServiceResponse<B>) -> (SessionStatus, SessionState) {
+        let Some(inner) = res
+            .request()
+            .extensions()
+            .get::<Rc<RefCell<SessionInner>>>()
+            .cloned()
+        else {
+            return (SessionStatus::Unchanged, SessionState::new());
+        };
+
+        let mut inner = inner.borrow_mut();
+        let status = inner.status.clone();
+        let state = mem::take(&mut inner.state);
+        (status, state)
+    }
+
+    pub(crate) fn get_session(extensions: &mut Extensions) -> Session {
+        if let Some(inner) = extensions.get::<Rc<RefCell<SessionInner>>>() {
+            return Session(Rc::clone(inner));
+        }
+
+        let inner = Rc::new(RefCell::new(SessionInner::default()));
+        extensions.insert(Rc::clone(&inner));
+        Session(inner)
+    }
 }
 
 impl Default for Session {
@@ -193,3 +234,18 @@ pub type SessionState = Map<String, Value>;
 
 #[derive(Debug, Clone, Copy)]
 pub struct SessionUser(pub Uuid);
+
+impl FromRequest for Session {
+    type Error = AppError;
+    type Future = Ready<Result<Self, Self::Error>>;
+
+    fn from_request(req: &HttpRequest, _payload: &mut Payload) -> Self::Future {
+        ready(Ok(Self::get_session(&mut req.extensions_mut())))
+    }
+}
+
+fn mark_changed(status: &mut SessionStatus) {
+    if *status != SessionStatus::Renewed {
+        *status = SessionStatus::Changed;
+    }
+}