1 files changed, 134 insertions, 0 deletions
diff --git a/azalea/src/swarm/plugins.rs b/azalea/src/swarm/plugins.rs
new file mode 100644
index 00000000..0c7cf2ae
--- /dev/null
+++ b/azalea/src/swarm/plugins.rs
@@ -0,0 +1,134 @@
+use crate::{Swarm, SwarmEvent};
+use async_trait::async_trait;
+use nohash_hasher::NoHashHasher;
+use std::{
+    any::{Any, TypeId},
+    collections::HashMap,
+    hash::BuildHasherDefault,
+};
+
+type U64Hasher = BuildHasherDefault<NoHashHasher<u64>>;
+
+// kind of based on https://docs.rs/http/latest/src/http/extensions.rs.html
+/// A map of plugin ids to [`SwarmPlugin`] trait objects. The client stores
+/// this so we can keep the state for our [`Swarm`] plugins.
+///
+/// If you're using azalea, you should generate this from the `swarm_plugins!` macro.
+#[derive(Clone, Default)]
+pub struct SwarmPlugins<S> {
+    map: Option<HashMap<TypeId, Box<dyn SwarmPlugin<S>>, U64Hasher>>,
+}
+
+#[derive(Clone)]
+pub struct SwarmPluginStates<S> {
+    map: Option<HashMap<TypeId, Box<dyn SwarmPluginState<S>>, U64Hasher>>,
+}
+
+impl<S> SwarmPluginStates<S> {
+    pub fn get<T: SwarmPluginState<S>>(&self) -> Option<&T> {
+        self.map
+            .as_ref()
+            .and_then(|map| map.get(&TypeId::of::<T>()))
+            .and_then(|boxed| (boxed.as_ref() as &dyn Any).downcast_ref::<T>())
+    }
+}
+
+impl<S> SwarmPlugins<S>
+where
+    S: 'static,
+{
+    /// Create a new empty set of plugins.
+    pub fn new() -> Self {
+        Self { map: None }
+    }
+
+    /// Add a new plugin to this set.
+    pub fn add<T: SwarmPlugin<S>>(&mut self, plugin: T) {
+        if self.map.is_none() {
+            self.map = Some(HashMap::with_hasher(BuildHasherDefault::default()));
+        }
+        self.map
+            .as_mut()
+            .unwrap()
+            .insert(TypeId::of::<T>(), Box::new(plugin));
+    }
+
+    /// Build our plugin states from this set of plugins. Note that if you're
+    /// using `azalea` you'll probably never need to use this as it's called
+    /// for you.
+    pub fn build(self) -> SwarmPluginStates<S> {
+        if self.map.is_none() {
+            return SwarmPluginStates { map: None };
+        }
+        let mut map = HashMap::with_hasher(BuildHasherDefault::default());
+        for (id, plugin) in self.map.unwrap().into_iter() {
+            map.insert(id, plugin.build());
+        }
+        SwarmPluginStates { map: Some(map) }
+    }
+}
+
+impl<S> IntoIterator for SwarmPluginStates<S> {
+    type Item = Box<dyn SwarmPluginState<S>>;
+    type IntoIter = std::vec::IntoIter<Self::Item>;
+
+    /// Iterate over the plugin states.
+    fn into_iter(self) -> Self::IntoIter {
+        self.map
+            .map(|map| map.into_values().collect::<Vec<_>>())
+            .unwrap_or_default()
+            .into_iter()
+    }
+}
+
+/// A `SwarmPluginState` keeps the current state of a plugin for a client. All
+/// the fields must be atomic. Unique `SwarmPluginState`s are built from
+/// [`SwarmPlugin`]s.
+#[async_trait]
+pub trait SwarmPluginState<S>: Send + Sync + SwarmPluginStateClone<S> + Any + 'static {
+    async fn handle(self: Box<Self>, event: SwarmEvent, swarm: Swarm<S>);
+}
+
+/// Swarm plugins can keep their own personal state ([`SwarmPluginState`]),
+/// listen to [`SwarmEvent`]s, and add new functions to [`Swarm`].
+pub trait SwarmPlugin<S>: Send + Sync + SwarmPluginClone<S> + Any + 'static {
+    fn build(&self) -> Box<dyn SwarmPluginState<S>>;
+}
+
+/// An internal trait that allows SwarmPluginState to be cloned.
+#[doc(hidden)]
+pub trait SwarmPluginStateClone<S> {
+    fn clone_box(&self) -> Box<dyn SwarmPluginState<S>>;
+}
+impl<T, S> SwarmPluginStateClone<S> for T
+where
+    T: 'static + SwarmPluginState<S> + Clone,
+{
+    fn clone_box(&self) -> Box<dyn SwarmPluginState<S>> {
+        Box::new(self.clone())
+    }
+}
+impl<S> Clone for Box<dyn SwarmPluginState<S>> {
+    fn clone(&self) -> Self {
+        self.clone_box()
+    }
+}
+
+/// An internal trait that allows SwarmPlugin to be cloned.
+#[doc(hidden)]
+pub trait SwarmPluginClone<S> {
+    fn clone_box(&self) -> Box<dyn SwarmPlugin<S>>;
+}
+impl<T, S> SwarmPluginClone<S> for T
+where
+    T: 'static + SwarmPlugin<S> + Clone,
+{
+    fn clone_box(&self) -> Box<dyn SwarmPlugin<S>> {
+        Box::new(self.clone())
+    }
+}
+impl<S> Clone for Box<dyn SwarmPlugin<S>> {
+    fn clone(&self) -> Self {
+        self.clone_box()
+    }
+}