Implement invulnerability/intangibility and sakurai angle (#78)

Reviewed-on: #78
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/mod.rs

@@ -85,12 +85,12 @@ pub struct FighterHitstop {
     pub remaining_frames: u32,
 }
 
-#[derive(Component, Default, Copy, Clone, Hash, PartialEq, Eq)]
+#[derive(Component, Default, Copy, Clone, Hash)]
 pub enum FighterInvulnerabilityState {
     #[default]
     Vulnerable,
-    Invulnerable,
-    Intangible
+    Invulnerable { frames_remaining: Option<u32> },
+    Intangible { frames_remaining: Option<u32> }
 }
 
 impl FighterFacingDirection {
@@ -179,7 +179,7 @@ impl Plugin for FighterPlugin {
             )
             .add_systems(
                 GgrsSchedule,
-                (state::state_update_system, decay_hitstop)
+                (state::state_update_system, decay_hitstop, decay_invulnerability)
                     .chain()
                     .in_set(GameplaySet::StateUpdate),
             )
@@ -360,3 +360,34 @@ pub fn decay_hitstop(query: Query<(&mut FighterHitstop, &mut FighterHitstopShake
         hitstop_shake.remaining_frames = hitstop_shake.remaining_frames.saturating_sub(1);
     }
 }
+
+pub fn decay_invulnerability(query: Query<&mut FighterInvulnerabilityState>) {
+    for invuln_state in query {
+        let invuln_state = invuln_state.into_inner();
+        let frames_remaining = match invuln_state {
+            FighterInvulnerabilityState::Vulnerable => None,
+            FighterInvulnerabilityState::Invulnerable { frames_remaining } => {
+                if let Some(frames_remaining) = frames_remaining {
+                    *frames_remaining = frames_remaining.saturating_sub(1);
+                    Some(*frames_remaining)
+                } else {
+                    None
+                }
+            },
+            FighterInvulnerabilityState::Intangible { frames_remaining } => {
+                if let Some(frames_remaining) = frames_remaining {
+                    *frames_remaining = frames_remaining.saturating_sub(1);
+                    Some(*frames_remaining)
+                } else {
+                    None
+                }
+            },
+        };
+
+        if let Some(frames_remaining) = frames_remaining {
+            if frames_remaining == 0 {
+                *invuln_state = FighterInvulnerabilityState::Vulnerable;
+            }
+        }
+    }
+}