Add TicksAlive component (#229)

* Add TicksAlive component

* Rename TicksAlive to TicksConnected

* Move component to plugins/tick_counter.rs and add doc comment

1 files changed, 37 insertions, 0 deletions

diff --git a/azalea-client/src/plugins/tick_counter.rs b/azalea-client/src/plugins/tick_counter.rs
new file mode 100644
index 00000000..21515959
--- /dev/null
+++ b/azalea-client/src/plugins/tick_counter.rs
@@ -0,0 +1,37 @@
+use azalea_core::tick::GameTick;
+use azalea_physics::PhysicsSet;
+use azalea_world::InstanceName;
+
+use bevy_app::{App, Plugin};
+use bevy_ecs::prelude::*;
+
+use crate::{mining::MiningSet, movement::send_position, tick_broadcast::send_tick_broadcast};
+
+/// Counts the number of game ticks elapsed on the **local client** since the
+/// `login` packet was received.
+#[derive(Component, Clone, Debug, Default)]
+pub struct TicksConnected(pub u64);
+
+/// Inserts the counter-increment system into the `GameTick` schedule **before**
+/// physics, mining and movement.
+pub struct TickCounterPlugin;
+
+impl Plugin for TickCounterPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_systems(
+            GameTick,
+            increment_counter
+                .before(PhysicsSet)
+                .before(MiningSet)
+                .before(send_position)
+                .before(send_tick_broadcast),
+        );
+    }
+}
+
+/// Increment the [`GameTickCounter`] on every entity that lives in an instance.
+fn increment_counter(mut query: Query<&mut TicksConnected, With<InstanceName>>) {
+    for mut counter in &mut query {
+        counter.0 += 1;
+    }
+}