1 files changed, 49 insertions, 0 deletions
diff --git a/src/login/snapshot.rs b/src/login/snapshot.rs
new file mode 100644
index 0000000..1379005
--- /dev/null
+++ b/src/login/snapshot.rs
@@ -0,0 +1,49 @@
+use super::{
+    event::{Created, Event},
+    Id,
+};
+
+// This also implements FromRequestParts (see `./extract.rs`). As a result, it
+// can be used as an extractor for endpoints that want to require login, or for
+// endpoints that need to behave differently depending on whether the client is
+// or is not logged in.
+#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
+pub struct Login {
+    pub id: Id,
+    pub name: String,
+    // The omission of the hashed password is deliberate, to minimize the
+    // chance that it ends up tangled up in debug output or in some other chunk
+    // of logic elsewhere.
+}
+
+impl Login {
+    // Two reasons for this allow:
+    //
+    // 1. This is used to collect streams using a fold, below, which requires a type consistent with the fold, and
+    // 2. It's also consistent with the other history state machine types.
+    #[allow(clippy::unnecessary_wraps)]
+    fn apply(state: Option<Self>, event: Event) -> Option<Self> {
+        match (state, event) {
+            (None, Event::Created(event)) => Some(event.into()),
+            (state, event) => panic!("invalid message event {event:#?} for state {state:#?}"),
+        }
+    }
+}
+
+impl FromIterator<Event> for Option<Login> {
+    fn from_iter<I: IntoIterator<Item = Event>>(events: I) -> Self {
+        events.into_iter().fold(None, Login::apply)
+    }
+}
+
+impl From<&Created> for Login {
+    fn from(event: &Created) -> Self {
+        event.login.clone()
+    }
+}
+
+impl From<Created> for Login {
+    fn from(event: Created) -> Self {
+        event.login
+    }
+}