From 9adf24618a943bab4ce39267760d3a5348519fb2 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Thu, 24 Sep 2026 18:57:36 +0200
Subject: feat(engine): add invalid asset IDs & handles

---
 engine/src/asset.rs | 69 +++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 56 insertions(+), 13 deletions(-)

diff --git a/engine/src/asset.rs b/engine/src/asset.rs
index 56b8a46..8337f5f 100644
--- a/engine/src/asset.rs
+++ b/engine/src/asset.rs
@@ -186,10 +186,12 @@ impl Assets
         handle: &Handle<Asset>,
     ) -> Option<&Asset>
     {
+        let id = handle.id.into_valid()?;
+
         let asset_lookup = self.asset_lookup.borrow();
 
         let LookupEntry::Occupied(asset_index, asset_label) =
-            asset_lookup.get(&handle.id.label_hash)?
+            asset_lookup.get(&id.label_hash)?
         else {
             return None;
         };
@@ -242,10 +244,14 @@ impl Assets
         handle: &Handle<Asset>,
     ) -> bool
     {
+        let Some(id) = handle.id.into_valid() else {
+            return false;
+        };
+
         let asset_lookup = self.asset_lookup.borrow();
 
         let Some(LookupEntry::Occupied(asset_index, _)) =
-            asset_lookup.get(&handle.id.label_hash)
+            asset_lookup.get(&id.label_hash)
         else {
             return false;
         };
@@ -262,11 +268,9 @@ impl Assets
         handle: &Handle<Asset>,
     ) -> Option<LabelOwned>
     {
-        let lookup_entry = self
-            .asset_lookup
-            .borrow()
-            .get(&handle.id.label_hash)?
-            .clone();
+        let id = handle.id.into_valid()?;
+
+        let lookup_entry = self.asset_lookup.borrow().get(&id.label_hash)?.clone();
 
         let LookupEntry::Occupied(_, label) = lookup_entry else {
             return None;
@@ -277,6 +281,8 @@ impl Assets
 
     pub fn get_label_by_id(&self, id: Id) -> Option<LabelOwned>
     {
+        let id = id.into_valid()?;
+
         let lookup_entry = self.asset_lookup.borrow().get(&id.label_hash)?.clone();
 
         let LookupEntry::Occupied(_, label) = lookup_entry else {
@@ -441,11 +447,15 @@ impl Assets
             .get_mut()
             .insert(label_hash, LookupEntry::Occupied(index, label.to_owned()));
 
+        let id = Id {
+            inner: IdInner::Valid(IdValid { label_hash }),
+        };
+
         self.events
             .curr_tick_events
-            .push(Event::Stored(Id { label_hash }, label.to_owned()));
+            .push(Event::Stored(id, label.to_owned()));
 
-        Handle::new(label_hash)
+        Handle::from_id(id)
     }
 
     pub fn events(&self) -> &Events
@@ -677,6 +687,11 @@ pub struct Handle<Asset: 'static>
 
 impl<Asset: 'static> Handle<Asset>
 {
+    pub fn invalid() -> Self
+    {
+        Self::from_id(Id::invalid())
+    }
+
     #[must_use]
     pub fn from_id(id: Id) -> Self
     {
@@ -691,10 +706,9 @@ impl<Asset: 'static> Handle<Asset>
 
     fn new(label_hash: LabelHash) -> Self
     {
-        Self {
-            id: Id { label_hash },
-            _pd: PhantomData,
-        }
+        Self::from_id(Id {
+            inner: IdInner::Valid(IdValid { label_hash }),
+        })
     }
 }
 
@@ -709,6 +723,35 @@ impl<Asset: 'static> Clone for Handle<Asset>
 /// Asset ID.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Id
+{
+    inner: IdInner,
+}
+
+impl Id
+{
+    pub fn invalid() -> Self
+    {
+        Self { inner: IdInner::Invalid }
+    }
+
+    fn into_valid(self) -> Option<IdValid>
+    {
+        match self.inner {
+            IdInner::Valid(id) => Some(id),
+            IdInner::Invalid => None,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+enum IdInner
+{
+    Valid(IdValid),
+    Invalid,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+struct IdValid
 {
     label_hash: LabelHash,
 }
-- 
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