Fix godmode mispredicts (#18524)

Co-authored-by: Leon Friedrich <60421075+ElectroJr@users.noreply.github.com>

Content.Shared/Damage/Components/GodmodeComponent.cs

@@ -0,0 +1,14 @@
+using Content.Shared.Damage.Systems;
+using Robust.Shared.GameStates;
+
+namespace Content.Shared.Damage.Components;
+
+[RegisterComponent, NetworkedComponent, Access(typeof(SharedGodmodeSystem))]
+public sealed class GodmodeComponent : Component
+{
+    [DataField("wasMovedByPressure")]
+    public bool WasMovedByPressure;
+
+    [DataField("oldDamage")]
+    public DamageSpecifier? OldDamage = null;
+}

Content.Shared/Damage/Systems/SharedGodmodeSystem.cs

@@ -0,0 +1,84 @@
+using Content.Shared.Damage.Components;
+using Content.Shared.Rejuvenate;
+using Content.Shared.Slippery;
+using Content.Shared.StatusEffect;
+
+namespace Content.Shared.Damage.Systems;
+
+public abstract class SharedGodmodeSystem : EntitySystem
+{
+    [Dependency] private readonly DamageableSystem _damageable = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<GodmodeComponent, BeforeDamageChangedEvent>(OnBeforeDamageChanged);
+        SubscribeLocalEvent<GodmodeComponent, BeforeStatusEffectAddedEvent>(OnBeforeStatusEffect);
+        SubscribeLocalEvent<GodmodeComponent, BeforeStaminaDamageEvent>(OnBeforeStaminaDamage);
+        SubscribeLocalEvent<GodmodeComponent, SlipAttemptEvent>(OnSlipAttempt);
+    }
+
+    private void OnSlipAttempt(EntityUid uid, GodmodeComponent component, SlipAttemptEvent args)
+    {
+        args.Cancel();
+    }
+
+    private void OnBeforeDamageChanged(EntityUid uid, GodmodeComponent component, ref BeforeDamageChangedEvent args)
+    {
+        args.Cancelled = true;
+    }
+
+    private void OnBeforeStatusEffect(EntityUid uid, GodmodeComponent component, ref BeforeStatusEffectAddedEvent args)
+    {
+        args.Cancelled = true;
+    }
+
+    private void OnBeforeStaminaDamage(EntityUid uid, GodmodeComponent component, ref BeforeStaminaDamageEvent args)
+    {
+        args.Cancelled = true;
+    }
+
+    public virtual void EnableGodmode(EntityUid uid, GodmodeComponent? godmode = null)
+    {
+        godmode ??= EnsureComp<GodmodeComponent>(uid);
+
+        if (TryComp<DamageableComponent>(uid, out var damageable))
+        {
+            godmode.OldDamage = new DamageSpecifier(damageable.Damage);
+        }
+
+        // Rejuv to cover other stuff
+        RaiseLocalEvent(uid, new RejuvenateEvent());
+    }
+
+    public virtual void DisableGodmode(EntityUid uid, GodmodeComponent? godmode = null)
+    {
+        if (!Resolve(uid, ref godmode, false))
+            return;
+
+        if (TryComp<DamageableComponent>(uid, out var damageable) && godmode.OldDamage != null)
+        {
+            _damageable.SetDamage(uid, damageable, godmode.OldDamage);
+        }
+
+        RemComp<GodmodeComponent>(uid);
+    }
+
+    /// <summary>
+    ///     Toggles godmode for a given entity.
+    /// </summary>
+    /// <param name="uid">The entity to toggle godmode for.</param>
+    /// <returns>true if enabled, false if disabled.</returns>
+    public bool ToggleGodmode(EntityUid uid)
+    {
+        if (TryComp<GodmodeComponent>(uid, out var godmode))
+        {
+            DisableGodmode(uid, godmode);
+            return false;
+        }
+
+        EnableGodmode(uid, godmode);
+        return true;
+    }
+}