make dragons breathe fire (#26746)

* add ActionGun system

* add RepeatingTrigger

* dragons breath projectile, repeatedly explodes

* give dragon fire breathing action, fireproof it

* oop

* oop 2

* prevent troll

* proper repeating thing

* pro

* webedit ops

* realops

---------

Co-authored-by: deltanedas <@deltanedas:kde.org>

Content.Server/Explosion/Components/ExplosiveComponent.cs

@@ -81,6 +81,13 @@ public sealed partial class ExplosiveComponent : Component
     [DataField("deleteAfterExplosion")]
     public bool? DeleteAfterExplosion;
 
+    /// <summary>
+    /// Whether to not set <see cref="Exploded"/> to true, allowing it to explode multiple times.
+    /// This should never be used if it is damageable.
+    /// </summary>
+    [DataField]
+    public bool Repeatable;
+
     /// <summary>
     ///     Avoid somehow double-triggering this explosion (e.g. by damaging this entity from its own explosion.
     /// </summary>

Content.Server/Explosion/Components/RepeatingTriggerComponent.cs

@@ -0,0 +1,25 @@
+using Content.Server.Explosion.EntitySystems;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom;
+
+namespace Content.Server.Explosion.Components;
+
+/// <summary>
+/// Constantly triggers after being added to an entity.
+/// </summary>
+[RegisterComponent, Access(typeof(TriggerSystem))]
+[AutoGenerateComponentPause]
+public sealed partial class RepeatingTriggerComponent : Component
+{
+    /// <summary>
+    /// How long to wait between triggers.
+    /// The first trigger starts this long after the component is added.
+    /// </summary>
+    [DataField]
+    public TimeSpan Delay = TimeSpan.FromSeconds(1);
+
+    /// <summary>
+    /// When the next trigger will be.
+    /// </summary>
+    [DataField(customTypeSerializer: typeof(TimeOffsetSerializer)), AutoPausedField]
+    public TimeSpan NextTrigger;
+}

Content.Server/Explosion/EntitySystems/ExplosionSystem.cs

@@ -160,7 +160,7 @@ public sealed partial class ExplosionSystem : EntitySystem
         if (explosive.Exploded)
             return;
 
-        explosive.Exploded = true;
+        explosive.Exploded = !explosive.Repeatable;
 
         // Override the explosion intensity if optional arguments were provided.
         if (radius != null)

Content.Server/Explosion/EntitySystems/TriggerSystem.cs

@@ -94,6 +94,7 @@ namespace Content.Server.Explosion.EntitySystems
             SubscribeLocalEvent<TriggerOnStepTriggerComponent, StepTriggeredOffEvent>(OnStepTriggered);
             SubscribeLocalEvent<TriggerOnSlipComponent, SlipEvent>(OnSlipTriggered);
             SubscribeLocalEvent<TriggerWhenEmptyComponent, OnEmptyGunShotEvent>(OnEmptyTriggered);
+            SubscribeLocalEvent<RepeatingTriggerComponent, MapInitEvent>(OnRepeatInit);
 
             SubscribeLocalEvent<SpawnOnTriggerComponent, TriggerEvent>(OnSpawnTrigger);
             SubscribeLocalEvent<DeleteOnTriggerComponent, TriggerEvent>(HandleDeleteTrigger);
@@ -241,6 +242,11 @@ namespace Content.Server.Explosion.EntitySystems
             Trigger(uid, args.EmptyGun);
         }
 
+        private void OnRepeatInit(Entity<RepeatingTriggerComponent> ent, ref MapInitEvent args)
+        {
+            ent.Comp.NextTrigger = _timing.CurTime + ent.Comp.Delay;
+        }
+
         public bool Trigger(EntityUid trigger, EntityUid? user = null)
         {
             var triggerEvent = new TriggerEvent(trigger, user);
@@ -323,6 +329,7 @@ namespace Content.Server.Explosion.EntitySystems
             UpdateProximity();
             UpdateTimer(frameTime);
             UpdateTimedCollide(frameTime);
+            UpdateRepeat();
         }
 
         private void UpdateTimer(float frameTime)
@@ -357,5 +364,19 @@ namespace Content.Server.Explosion.EntitySystems
                     _appearance.SetData(uid, TriggerVisuals.VisualState, TriggerVisualState.Unprimed, appearance);
             }
         }
+
+        private void UpdateRepeat()
+        {
+            var now = _timing.CurTime;
+            var query = EntityQueryEnumerator<RepeatingTriggerComponent>();
+            while (query.MoveNext(out var uid, out var comp))
+            {
+                if (comp.NextTrigger > now)
+                    continue;
+
+                comp.NextTrigger = now + comp.Delay;
+                Trigger(uid);
+            }
+        }
     }
 }