Hot potato on fire (#16017)

Content.Shared/Damage/Components/DamageOnHoldingComponent.cs

@@ -0,0 +1,33 @@
+using Content.Shared.Damage.Systems;
+using Robust.Shared.GameStates;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom;
+
+namespace Content.Shared.Damage.Components;
+
+[RegisterComponent, NetworkedComponent]
+[AutoGenerateComponentState]
+[Access(typeof(DamageOnHoldingSystem))]
+public sealed partial class DamageOnHoldingComponent : Component
+{
+    [DataField("enabled"), ViewVariables(VVAccess.ReadWrite)]
+    [AutoNetworkedField]
+    public bool Enabled = true;
+
+    /// <summary>
+    /// Damage per interval dealt to entity holding the entity with this component
+    /// </summary>
+    [DataField("damage"), ViewVariables(VVAccess.ReadWrite)]
+    public DamageSpecifier Damage = new();
+    // TODO: make it networked
+
+    /// <summary>
+    /// Delay between damage events in seconds
+    /// </summary>
+    [DataField("interval"), ViewVariables(VVAccess.ReadWrite)]
+    [AutoNetworkedField]
+    public float Interval = 1f;
+
+    [DataField("nextDamage", customTypeSerializer: typeof(TimeOffsetSerializer)), ViewVariables(VVAccess.ReadWrite)]
+    [AutoNetworkedField]
+    public TimeSpan NextDamage = TimeSpan.Zero;
+}

Content.Shared/Damage/Systems/DamageOnHoldingSystem.cs

@@ -0,0 +1,53 @@
+using Content.Shared.Damage.Components;
+using Robust.Shared.Containers;
+using Robust.Shared.Timing;
+
+namespace Content.Shared.Damage.Systems;
+
+public sealed class DamageOnHoldingSystem : EntitySystem
+{
+    [Dependency] private readonly SharedContainerSystem _container = default!;
+    [Dependency] private readonly DamageableSystem _damageableSystem = default!;
+    [Dependency] private readonly IGameTiming _timing = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<DamageOnHoldingComponent, EntityUnpausedEvent>(OnUnpaused);
+        SubscribeLocalEvent<DamageOnHoldingComponent, MapInitEvent>(OnMapInit);
+    }
+
+    public void SetEnabled(EntityUid uid, bool enabled, DamageOnHoldingComponent? component = null)
+    {
+        if (Resolve(uid, ref component))
+        {
+            component.Enabled = enabled;
+            component.NextDamage = _timing.CurTime;
+        }
+    }
+
+    private void OnUnpaused(EntityUid uid, DamageOnHoldingComponent component, ref EntityUnpausedEvent args)
+    {
+        component.NextDamage += args.PausedTime;
+    }
+
+    private void OnMapInit(EntityUid uid, DamageOnHoldingComponent component, MapInitEvent args)
+    {
+        component.NextDamage = _timing.CurTime;
+    }
+
+    public override void Update(float frameTime)
+    {
+        var query = EntityQueryEnumerator<DamageOnHoldingComponent>();
+        while (query.MoveNext(out var uid, out var component))
+        {
+            if (!component.Enabled || component.NextDamage > _timing.CurTime)
+                continue;
+            if (_container.TryGetContainingContainer(uid, out var container))
+            {
+                _damageableSystem.TryChangeDamage(container.Owner, component.Damage, origin: uid);
+            }
+            component.NextDamage = _timing.CurTime + TimeSpan.FromSeconds(component.Interval);
+        }
+    }
+}

Content.Shared/HotPotato/HotPotatoComponent.cs

@@ -3,7 +3,7 @@ using Robust.Shared.GameStates;
 namespace Content.Shared.HotPotato;
 
 /// <summary>
-/// Similar to <see cref="Content.Shared.Interaction.Components.UnremoveableComponent"/>
+/// Similar to <see cref="Interaction.Components.UnremoveableComponent"/>
 /// except entities with this component can be removed in specific case: <see cref="CanTransfer"/>
 /// </summary>
 [RegisterComponent, NetworkedComponent]