1 files changed, 73 insertions, 0 deletions
diff --git a/engine-ecs/src/phase.rs b/engine-ecs/src/phase.rs
new file mode 100644
index 0000000..78428c4
--- /dev/null
+++ b/engine-ecs/src/phase.rs
@@ -0,0 +1,73 @@
+use crate::{declare_entity, Component, World};
+
+#[derive(Debug, Default, Clone, Copy, Component)]
+pub struct Phase;
+
+declare_entity! {
+/// Initialization phase that only occurs the first tick, before [`START`].
+/// Should not be used for game logic
+pub INIT: (Phase,);
+
+/// Phase that only occurs the first tick, after [`INIT`].
+pub START: (Phase,);
+
+/// Phase that occurs every tick, before [`UPDATE`].
+pub PRE_UPDATE: (Phase,);
+
+/// Phase that occurs every tick, after [`PRE_UPDATE`].
+pub UPDATE: (Phase,);
+
+/// Phase that occurs every tick, after [`UPDATE`].
+pub POST_UPDATE: (Phase,);
+}
+
+pub(crate) fn spawn_standard_phases(world: &mut World)
+{
+    world.spawn_declared_entity(&INIT);
+    world.spawn_declared_entity(&START);
+    world.spawn_declared_entity(&PRE_UPDATE);
+    world.spawn_declared_entity(&UPDATE);
+    world.spawn_declared_entity(&POST_UPDATE);
+}
+
+#[derive(Debug, Component)]
+pub(crate) struct HasSystem;
+
+#[cfg(debug_assertions)]
+pub(crate) fn check_parents(
+    phase_query: crate::query::Query<(
+        crate::pair::Pair<crate::pair::ChildOf, crate::pair::Wildcard>,
+        Option<&crate::entity::Name>,
+        crate::query::term::With<Phase>,
+    )>,
+)
+{
+    for (child_of, ent_name) in &phase_query {
+        let Some(parent_ent) = child_of.get_target_ent() else {
+            tracing::warn!(
+                phase_entity = ent_name
+                    .as_ref()
+                    .map(|ent_name| ent_name.name.as_ref())
+                    .unwrap_or("<unnamed>"),
+                "Parent entity of phase entity does not exist"
+            );
+            continue;
+        };
+
+        if !parent_ent.has_component(Phase::id()) {
+            let parent_ent_name = parent_ent.get::<crate::entity::Name>();
+
+            tracing::warn!(
+                phase_entity = ent_name
+                    .as_ref()
+                    .map(|ent_name| ent_name.name.as_ref())
+                    .unwrap_or("<unnamed>"),
+                parent_entity = parent_ent_name
+                    .as_ref()
+                    .map(|parent_ent_name| parent_ent_name.name.as_ref())
+                    .unwrap_or("<unnamed>"),
+                "Parent entity of phase entity is not a phase (missing Phase component)"
+            );
+        }
+    }
+}