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/AtmosphereSystem.API.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics;
 using System.Linq;
 using Content.Server.Atmos.Components;
 using Content.Server.Atmos.Piping.Components;
@@ -5,6 +6,7 @@ using Content.Server.NodeContainer.NodeGroups;
 using Content.Shared.Atmos;
 using Content.Shared.Atmos.Components;
 using Content.Shared.Atmos.Reactions;
+using JetBrains.Annotations;
 using Robust.Shared.Map.Components;
 using Robust.Shared.Utility;
 
@@ -319,6 +321,107 @@ public partial class AtmosphereSystem
         return true;
     }
 
+    /// <summary>
+    /// Adds an entity with a DeltaPressureComponent to the DeltaPressure processing list.
+    /// Also fills in important information on the component itself.
+    /// </summary>
+    /// <param name="grid">The grid to add the entity to.</param>
+    /// <param name="ent">The entity to add.</param>
+    /// <returns>True if the entity was added to the list, false if it could not be added or
+    /// if the entity was already present in the list.</returns>
+    [PublicAPI]
+    public bool TryAddDeltaPressureEntity(Entity<GridAtmosphereComponent?> grid, Entity<DeltaPressureComponent> ent)
+    {
+        // The entity needs to be part of a grid, and it should be the right one :)
+        var xform = Transform(ent);
+
+        // The entity is not on a grid, so it cannot possibly have an atmosphere that affects it.
+        if (xform.GridUid == null)
+        {
+            return false;
+        }
+
+        // Entity should be on the grid it's being added to.
+        Debug.Assert(xform.GridUid == grid.Owner);
+
+        if (!_atmosQuery.Resolve(grid, ref grid.Comp, false))
+            return false;
+
+        if (grid.Comp.DeltaPressureEntityLookup.ContainsKey(ent.Owner))
+        {
+            return false;
+        }
+
+        grid.Comp.DeltaPressureEntityLookup[ent.Owner] = grid.Comp.DeltaPressureEntities.Count;
+        grid.Comp.DeltaPressureEntities.Add(ent);
+
+        ent.Comp.CurrentPosition = _map.CoordinatesToTile(grid,
+            Comp<MapGridComponent>(grid),
+            xform.Coordinates);
+
+        ent.Comp.GridUid = grid.Owner;
+        ent.Comp.InProcessingList = true;
+
+        return true;
+    }
+
+    /// <summary>
+    /// Removes an entity with a DeltaPressureComponent from the DeltaPressure processing list.
+    /// </summary>
+    /// <param name="grid">The grid to remove the entity from.</param>
+    /// <param name="ent">The entity to remove.</param>
+    /// <returns>True if the entity was removed from the list, false if it could not be removed or
+    /// if the entity was not present in the list.</returns>
+    [PublicAPI]
+    public bool TryRemoveDeltaPressureEntity(Entity<GridAtmosphereComponent?> grid, Entity<DeltaPressureComponent> ent)
+    {
+        if (!_atmosQuery.Resolve(grid, ref grid.Comp, false))
+            return false;
+
+        if (!grid.Comp.DeltaPressureEntityLookup.TryGetValue(ent.Owner, out var index))
+            return false;
+
+        var lastIndex = grid.Comp.DeltaPressureEntities.Count - 1;
+        if (lastIndex < 0)
+            return false;
+
+        if (index != lastIndex)
+        {
+            var lastEnt = grid.Comp.DeltaPressureEntities[lastIndex];
+            grid.Comp.DeltaPressureEntities[index] = lastEnt;
+            grid.Comp.DeltaPressureEntityLookup[lastEnt.Owner] = index;
+        }
+
+        grid.Comp.DeltaPressureEntities.RemoveAt(lastIndex);
+        grid.Comp.DeltaPressureEntityLookup.Remove(ent.Owner);
+
+        if (grid.Comp.DeltaPressureCursor > grid.Comp.DeltaPressureEntities.Count)
+            grid.Comp.DeltaPressureCursor = grid.Comp.DeltaPressureEntities.Count;
+
+        ent.Comp.InProcessingList = false;
+        ent.Comp.GridUid = null;
+        return true;
+    }
+
+    /// <summary>
+    /// Checks if a DeltaPressureComponent is currently considered for processing on a grid.
+    /// </summary>
+    /// <param name="grid">The grid that the entity may belong to.</param>
+    /// <param name="ent">The entity to check.</param>
+    /// <returns>True if the entity is part of the processing list, false otherwise.</returns>
+    [PublicAPI]
+    public bool IsDeltaPressureEntityInList(Entity<GridAtmosphereComponent?> grid, Entity<DeltaPressureComponent> ent)
+    {
+        // Dict and list must be in sync - deep-fried if we aren't.
+        if (!_atmosQuery.Resolve(grid, ref grid.Comp, false))
+            return false;
+
+        var contains = grid.Comp.DeltaPressureEntityLookup.ContainsKey(ent.Owner);
+        Debug.Assert(contains == grid.Comp.DeltaPressureEntities.Contains(ent));
+
+        return contains;
+    }
+
     [ByRefEvent] private record struct SetSimulatedGridMethodEvent
         (EntityUid Grid, bool Simulated, bool Handled = false);