Blindness refactor (#15705)

Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Shared/Eye/Blinding/Systems/BlurryVisionSystem.cs

@@ -0,0 +1,72 @@
+using Content.Shared.Eye.Blinding.Components;
+using Content.Shared.Inventory.Events;
+using Content.Shared.Inventory;
+
+namespace Content.Shared.Eye.Blinding.Systems;
+
+public sealed class BlurryVisionSystem : EntitySystem
+{
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<BlindableComponent, EyeDamageChangedEvent>(OnDamageChanged);
+        SubscribeLocalEvent<VisionCorrectionComponent, GotEquippedEvent>(OnGlassesEquipped);
+        SubscribeLocalEvent<VisionCorrectionComponent, GotUnequippedEvent>(OnGlassesUnequipped);
+        SubscribeLocalEvent<VisionCorrectionComponent, InventoryRelayedEvent<GetBlurEvent>>(OnGetBlur);
+    }
+
+    private void OnGetBlur(EntityUid uid, VisionCorrectionComponent component, InventoryRelayedEvent<GetBlurEvent> args)
+    {
+        args.Args.Blur += component.VisionBonus;
+    }
+
+    private void OnDamageChanged(EntityUid uid, BlindableComponent component, ref EyeDamageChangedEvent args)
+    {
+        UpdateBlurMagnitude(uid, component);
+    }
+
+    private void UpdateBlurMagnitude(EntityUid uid, BlindableComponent? component = null)
+    {
+        if (!Resolve(uid, ref component, false))
+            return;
+
+        var ev = new GetBlurEvent(component.EyeDamage);
+        RaiseLocalEvent(uid, ev);
+
+        var blur = Math.Clamp(0, ev.Blur, BlurryVisionComponent.MaxMagnitude);
+        if (blur <= 0)
+        {
+            RemCompDeferred<BlurryVisionComponent>(uid);
+            return;
+        }
+
+        var blurry = EnsureComp<BlurryVisionComponent>(uid);
+        blurry.Magnitude = blur;
+        Dirty(blurry);
+    }
+
+    private void OnGlassesEquipped(EntityUid uid, VisionCorrectionComponent component, GotEquippedEvent args)
+    {
+        UpdateBlurMagnitude(uid);
+    }
+
+    private void OnGlassesUnequipped(EntityUid uid, VisionCorrectionComponent component, GotUnequippedEvent args)
+    {
+        UpdateBlurMagnitude(uid);
+    }
+}
+
+public sealed class GetBlurEvent : EntityEventArgs, IInventoryRelayEvent
+{
+    public readonly float BaseBlur;
+    public float Blur;
+
+    public GetBlurEvent(float blur)
+    {
+        Blur = blur;
+        BaseBlur = blur;
+    }
+
+    public SlotFlags TargetSlots => SlotFlags.HEAD | SlotFlags.MASK | SlotFlags.EYES;
+}