1 files changed, 37 insertions, 0 deletions
diff --git a/src/app.rs b/src/app.rs
new file mode 100644
index 0000000..43e2ac6
--- /dev/null
+++ b/src/app.rs
@@ -0,0 +1,37 @@
+//! Internal app logic.
+
+use crate::session::Session;
+use std::collections::HashMap;
+use std::sync::{Mutex, MutexGuard, RwLock};
+
+/// Provider of the state that Tabletop Ambulator needs to keep track of.
+///
+/// Provides the app state, including runtime data such as the active game
+/// sessions. It provides access to relevant data through synchronization
+/// primitives, but does not handle shared ownership; for that, you may
+/// want to use a solution like [`std::sync::Arc`].
+#[derive(Debug, Default)]
+pub struct AppState {
+    sessions: RwLock<HashMap<String, Mutex<Session>>>,
+}
+
+impl AppState {
+    /// Creates a new `AppState`.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Creates and stores a new [`Session`], which can later be accessed with [`with_session`].
+    pub fn create_session(&self, id: String, name: String) {
+        let session = Mutex::new(Session::new(name));
+        self.sessions.write().unwrap().insert(id, session);
+    }
+
+    /// Finds a [`Session`] by the provided `id`. If the session exists, it is provided within a
+    /// [`MutexGuard`] to the supplied function. Returns the result of the function, or `None` if
+    /// there was no session with the supplied id.
+    pub fn with_session<T>(&self, id: &str, f: impl FnOnce(MutexGuard<Session>) -> T) -> Option<T> {
+        let sessions = self.sessions.read().unwrap();
+        sessions.get(id).map(|session| f(session.lock().unwrap()))
+    }
+}