Add Modular grenades (chemnades). (#7138)

Content.Shared/Payload/Components/PayloadTriggerComponent.cs

@@ -0,0 +1,45 @@
+using Robust.Shared.GameStates;
+using Robust.Shared.Prototypes;
+
+namespace Content.Shared.Payload.Components;
+
+/// <summary>
+///     Component for providing the means of triggering an explosive payload. Used in grenade construction.
+/// </summary>
+/// <remarks>
+///     This component performs two functions. Firstly, it will add or remove other components to some entity when this
+///     item is installed inside of it. This is intended for use with constructible grenades. For example, this allows
+///     you to add things like <see cref="OnUseTimerTriggerComponent"/>, or <see cref="TriggerOnProximityComponent"/>.
+///     This is required because otherwise you would have to forward arbitrary interaction directed at the casing
+///     through to the trigger, which would be quite complicated. Also proximity triggers don't really work inside of
+///     containers.
+///
+///     Secondly, if the entity that this component is attached to is ever triggered directly (e.g., via a device
+///     network message), the trigger will be forwarded to the device that this entity is installed in (if any).
+/// </remarks>
+[RegisterComponent, NetworkedComponent]
+public sealed class PayloadTriggerComponent : Component
+{
+    /// <summary>
+    ///     If true, triggering this entity will also cause the parent of this entity to be triggered.
+    /// </summary>
+    public bool Active = false;
+
+    /// <summary>
+    ///     List of components to add or remove from an entity when this trigger is (un)installed.
+    /// </summary>
+    [DataField("components", serverOnly:true, readOnly: true)]
+    public readonly EntityPrototype.ComponentRegistry? Components = null;
+
+    /// <summary>
+    ///     Keeps track of what components this trigger has granted to the payload case.
+    /// </summary>
+    /// <remarks>
+    ///     This is required in case someone creates a construction graph that accepts more than one trigger, and those
+    ///     trigger grant the same type of component (or the case just innately has that component). This list is used
+    ///     when removing the component, to ensure that removal of this trigger only removes the components that it was
+    ///     responsible for adding.
+    /// </remarks>
+    [DataField("grantedComponents", serverOnly: true)]
+    public readonly HashSet<Type> GrantedComponents = new();
+}