Atmos Delta-Pressure Window Shattering (#39238)

This PR adds delta-pressure damage. In short, airtight structures can now take damage proportional to the difference in pressures between the sides of the structure.

Content.Server/Atmos/EntitySystems/DeltaPressureSystem.cs

@@ -0,0 +1,82 @@
+using Content.Server.Atmos.Components;
+using Content.Shared.Examine;
+using Robust.Shared.Map.Components;
+
+namespace Content.Server.Atmos.EntitySystems;
+
+/// <summary>
+/// <para>System that handles <see cref="DeltaPressureComponent"/>.</para>
+///
+/// <para>Entities with a <see cref="DeltaPressureComponent"/> will take damage per atmostick
+/// depending on the pressure they experience.</para>
+///
+/// <para>DeltaPressure logic is mostly handled in a partial class in Atmospherics.
+/// This system handles the adding and removing of entities to a processing list,
+/// as well as any field changes via the API.</para>
+/// </summary>
+public sealed class DeltaPressureSystem : EntitySystem
+{
+    [Dependency] private readonly AtmosphereSystem _atmosphereSystem = default!;
+    [Dependency] private readonly SharedMapSystem _map = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<DeltaPressureComponent, ComponentInit>(OnComponentInit);
+        SubscribeLocalEvent<DeltaPressureComponent, ComponentShutdown>(OnComponentShutdown);
+        SubscribeLocalEvent<DeltaPressureComponent, ExaminedEvent>(OnExamined);
+        SubscribeLocalEvent<DeltaPressureComponent, MoveEvent>(OnMoveEvent);
+
+        SubscribeLocalEvent<DeltaPressureComponent, GridUidChangedEvent>(OnGridChanged);
+    }
+
+    private void OnMoveEvent(Entity<DeltaPressureComponent> ent, ref MoveEvent args)
+    {
+        var xform = Transform(ent);
+        // May move off-grid, so, might as well protect against that.
+        if (!TryComp<MapGridComponent>(xform.GridUid, out var mapGridComponent))
+        {
+            return;
+        }
+
+        ent.Comp.CurrentPosition = _map.CoordinatesToTile(xform.GridUid.Value, mapGridComponent, args.NewPosition);
+    }
+
+    private void OnComponentInit(Entity<DeltaPressureComponent> ent, ref ComponentInit args)
+    {
+        var xform = Transform(ent);
+        if (xform.GridUid == null)
+            return;
+
+        _atmosphereSystem.TryAddDeltaPressureEntity(xform.GridUid.Value, ent);
+    }
+
+    private void OnComponentShutdown(Entity<DeltaPressureComponent> ent, ref ComponentShutdown args)
+    {
+        // Wasn't part of a list, so nothing to clean up.
+        if (ent.Comp.GridUid == null)
+            return;
+
+        _atmosphereSystem.TryRemoveDeltaPressureEntity(ent.Comp.GridUid.Value, ent);
+    }
+
+    private void OnExamined(Entity<DeltaPressureComponent> ent, ref ExaminedEvent args)
+    {
+        if (ent.Comp.IsTakingDamage)
+            args.PushMarkup(Loc.GetString("window-taking-damage"));
+    }
+
+    private void OnGridChanged(Entity<DeltaPressureComponent> ent, ref GridUidChangedEvent args)
+    {
+        if (args.OldGrid != null)
+        {
+            _atmosphereSystem.TryRemoveDeltaPressureEntity(args.OldGrid.Value, ent);
+        }
+
+        if (args.NewGrid != null)
+        {
+            _atmosphereSystem.TryAddDeltaPressureEntity(args.NewGrid.Value, ent);
+        }
+    }
+}