Xenoarchaeology artifacts (#6069)

Co-authored-by: Alexander Evgrashin <evgrashin.adl@gmail.com>

Content.Server/Xenoarchaeology/XenoArtifacts/Triggers/Systems/ArtifactGasTriggerSystem.cs

@@ -0,0 +1,51 @@
+using Content.Server.Atmos.EntitySystems;
+using Content.Server.Xenoarchaeology.XenoArtifacts.Triggers.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Random;
+
+namespace Content.Server.Xenoarchaeology.XenoArtifacts.Triggers.Systems;
+
+public class ArtifactGasTriggerSystem : EntitySystem
+{
+    [Dependency] private readonly IRobustRandom _random = default!;
+    [Dependency] private readonly AtmosphereSystem _atmosphereSystem = default!;
+    [Dependency] private readonly ArtifactSystem _artifactSystem = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<ArtifactGasTriggerComponent, ComponentInit>(OnInit);
+    }
+
+    public override void Update(float frameTime)
+    {
+        base.Update(frameTime);
+        var query = EntityManager.EntityQuery<ArtifactGasTriggerComponent, TransformComponent>();
+        foreach (var (trigger, transform) in query)
+        {
+            if (trigger.ActivationGas == null)
+                return;
+
+            var environment = _atmosphereSystem.GetTileMixture(transform.Coordinates, true);
+            if (environment == null)
+                return;
+
+            // check if outside there is enough moles to activate artifact
+            var moles = environment.GetMoles(trigger.ActivationGas.Value);
+            if (moles < trigger.ActivationMoles)
+                return;
+
+            _artifactSystem.TryActivateArtifact(trigger.Owner);
+        }
+    }
+
+    private void OnInit(EntityUid uid, ArtifactGasTriggerComponent component, ComponentInit args)
+    {
+        if (component.ActivationGas == null)
+        {
+            var gas = _random.Pick(component.PossibleGases);
+            component.ActivationGas = gas;
+        }
+    }
+}