Make combat reaction state rollback-safe (#34)

## Summary

- replace the per-fighter received-attack inbox with a typed rollback-registered pending-hit resource
- split combat reaction resolution into its own attack module
- remap entity references during rollback and include pending hits in debug save states

Fixes #21

Reviewed-on: #34
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/debug_tools/save_state.rs

@@ -8,8 +8,8 @@ use crate::{
         FighterVelocity, Grounded,
         animation::FighterAnimationFrame,
         attack::{
-            FighterDamage, FighterKnockbackVelocity, FighterPendingHitReaction,
-            FighterReceivedAttacks, FighterSolvedHurtboxes, FighterStaleMoveQueue,
+            FighterDamage, FighterKnockbackVelocity, FighterPendingHitReaction, FighterPendingHits,
+            FighterSolvedHurtboxes, FighterStaleMoveQueue,
         },
         baked_animation::FighterBoneMatrices,
         state::FighterState,
@@ -28,6 +28,7 @@ pub(super) struct DebugSaveState {
 struct Checkpoint {
     fighters: Vec<FighterCheckpoint>,
     stage_collision: StageCollision,
+    pending_hits: FighterPendingHits,
 }
 
 #[derive(Clone)]
@@ -50,7 +51,6 @@ struct FighterCheckpoint {
     knockback_velocity: FighterKnockbackVelocity,
     stale_moves: FighterStaleMoveQueue,
     hitboxes: FighterHitboxes,
-    received_attacks: FighterReceivedAttacks,
     solved_hurtboxes: FighterSolvedHurtboxes,
     bone_matrices: FighterBoneMatrices,
     grounded: bool,
@@ -97,9 +97,11 @@ pub(super) fn save_or_restore(world: &mut World) {
             };
             checkpoint_fighters.push(checkpoint);
         }
+        let pending_hits = world.resource::<FighterPendingHits>().clone();
         world.resource_mut::<DebugSaveState>().checkpoint = Some(Checkpoint {
             fighters: checkpoint_fighters,
             stage_collision,
+            pending_hits,
         });
         info!("Saved debug game state");
         return;
@@ -147,7 +149,6 @@ pub(super) fn save_or_restore(world: &mut World) {
         entity.insert(saved.knockback_velocity);
         entity.insert(saved.stale_moves.clone());
         entity.insert(saved.hitboxes.clone());
-        entity.insert(saved.received_attacks.clone());
         entity.insert(saved.solved_hurtboxes.clone());
         entity.insert(saved.bone_matrices.clone());
         if saved.grounded {
@@ -156,6 +157,7 @@ pub(super) fn save_or_restore(world: &mut World) {
             entity.remove::<Grounded>();
         }
     }
+    world.insert_resource(checkpoint.pending_hits.clone());
     world.insert_resource(checkpoint.stage_collision);
     for mut match_camera in world.query::<&mut MatchCamera>().iter_mut(world) {
         match_camera.needs_snap = true;
@@ -184,7 +186,6 @@ fn capture_fighter(world: &World, entity: Entity) -> Option<FighterCheckpoint> {
         knockback_velocity: *fighter.get::<FighterKnockbackVelocity>()?,
         stale_moves: fighter.get::<FighterStaleMoveQueue>()?.clone(),
         hitboxes: fighter.get::<FighterHitboxes>()?.clone(),
-        received_attacks: fighter.get::<FighterReceivedAttacks>()?.clone(),
         solved_hurtboxes: fighter.get::<FighterSolvedHurtboxes>()?.clone(),
         bone_matrices: fighter.get::<FighterBoneMatrices>()?.clone(),
         grounded: fighter.contains::<Grounded>(),