From 28438c40c09bb52f8bd444b6f5cf9b34bdf71fee Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Mon, 12 Aug 2024 19:43:47 +0200
Subject: feat(ecs): add action for removing components(s) from entity

---
 ecs/src/actions.rs           | 16 +++++++++++++++-
 ecs/src/component/storage.rs | 30 ++++++++++++++++++++++++++++++
 ecs/src/lib.rs               | 13 +++++++++++++
 3 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/ecs/src/actions.rs b/ecs/src/actions.rs
index 038f617..7698b45 100644
--- a/ecs/src/actions.rs
+++ b/ecs/src/actions.rs
@@ -2,7 +2,11 @@ use std::any::Any;
 use std::marker::PhantomData;
 use std::sync::{Arc, Weak};
 
-use crate::component::{Component, Sequence as ComponentSequence};
+use crate::component::{
+    Component,
+    Metadata as ComponentMetadata,
+    Sequence as ComponentSequence,
+};
 use crate::entity::Uid as EntityUid;
 use crate::lock::{Lock, WriteGuard};
 use crate::system::{NoInitParamFlag, Param as SystemParam, System};
@@ -33,6 +37,15 @@ impl<'world> Actions<'world>
             .push(Action::AddComponents(entity_uid, components.into_vec()));
     }
 
+    /// Removes component(s) from a entity.
+    pub fn remove_components<Comps>(&mut self, entity_uid: EntityUid)
+    where
+        Comps: ComponentSequence,
+    {
+        self.action_queue
+            .push(Action::RemoveComponents(entity_uid, Comps::metadata()));
+    }
+
     /// Adds stopping the loop in [`Engine::event_loop`] at the next opportune time to the
     /// action queue.
     pub fn stop(&mut self)
@@ -140,6 +153,7 @@ pub(crate) enum Action
 {
     Spawn(Vec<Box<dyn Component>>),
     AddComponents(EntityUid, Vec<Box<dyn Component>>),
+    RemoveComponents(EntityUid, Vec<ComponentMetadata>),
     Stop,
 }
 
diff --git a/ecs/src/component/storage.rs b/ecs/src/component/storage.rs
index 76e1a7e..05ede9b 100644
--- a/ecs/src/component/storage.rs
+++ b/ecs/src/component/storage.rs
@@ -174,6 +174,36 @@ impl Storage
         Some(())
     }
 
+    pub fn remove_components_from_entity(
+        &mut self,
+        entity_uid: EntityUid,
+        component_ids: impl IntoIterator<Item = ComponentId>,
+    ) -> Option<()>
+    {
+        let archetype_id = self.entity_archetype_lookup.get(&entity_uid)?;
+
+        let archetype_index =
+            self.find_archetype_index_with_entity(*archetype_id, entity_uid)?;
+
+        let archetype = self.archetypes.get_mut(archetype_index)?;
+
+        let entity = archetype.take_entity(entity_uid)?;
+
+        let component_ids_set = component_ids.into_iter().collect::<HashSet<_>>();
+
+        self.push_entity(
+            entity_uid,
+            entity
+                .components
+                .into_iter()
+                .map(|component| component.component.into_inner())
+                .filter(|component| !component_ids_set.contains(&component.id()))
+                .collect(),
+        );
+
+        Some(())
+    }
+
     fn populate_matching_archetype_lookup_entries(
         &mut self,
         comp_ids_set: &HashSet<ComponentId>,
diff --git a/ecs/src/lib.rs b/ecs/src/lib.rs
index df65cb3..04c9b9f 100644
--- a/ecs/src/lib.rs
+++ b/ecs/src/lib.rs
@@ -170,6 +170,19 @@ impl World
                     component_storage_lock
                         .add_components_to_entity(entity_uid, components);
                 }
+                Action::RemoveComponents(entity_uid, component_ids) => {
+                    let mut component_storage_lock =
+                        self.data.component_storage.write_nonblock().expect(
+                            "Failed to acquire read-write component storage lock",
+                        );
+
+                    component_storage_lock.remove_components_from_entity(
+                        entity_uid,
+                        component_ids
+                            .iter()
+                            .map(|component_metadata| component_metadata.id),
+                    );
+                }
                 Action::Stop => {
                     self.stop.store(true, Ordering::Relaxed);
                 }
-- 
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