user/middleware: Add comments to Middleware implementation

Author: Turbo87

src/user/middleware.rs

@@ -13,18 +13,30 @@ pub struct Middleware;
 
 impl conduit_middleware::Middleware for Middleware {
     fn before(&self, req: &mut Request) -> Result<(), Box<Error+Send>> {
+        // Check if the request has a session cookie with a `user_id` property inside
         let id = { req.session().get("user_id").and_then(|s| s.parse().ok()) };
+
         let user = match id {
+
+            // `user_id` was found on the session
             Some(id) => {
+
+                // Look for a user in the database with the given `user_id`
                 match User::find(try!(req.tx().map_err(std_error)), id) {
                     Ok(user) => user,
                     Err(..) => return Ok(()),
                 }
             }
+
+            // `user_id` was *not* found on the session
             None => {
+
+                // Look for an `Authorization` header on the request
                 let tx = try!(req.tx().map_err(std_error));
                 match req.headers().find("Authorization") {
                     Some(headers) => {
+
+                        // Look for a user in the database with a matching API token
                         match User::find_by_api_token(tx, &headers[0]) {
                             Ok(user) => user,
                             Err(..) => return Ok(())
@@ -35,6 +47,7 @@ impl conduit_middleware::Middleware for Middleware {
             }
         };
 
+        // Attach the `User` model from the database to the request
         req.mut_extensions().insert(user);
         Ok(())
     }