Gas tile overlay state handling changes (#12691)

Content.Shared/Atmos/Components/GasTileOverlayComponent.cs

@@ -0,0 +1,81 @@
+using Robust.Shared.GameStates;
+using Robust.Shared.Serialization;
+using Robust.Shared.Timing;
+using Robust.Shared.Utility;
+
+namespace Content.Shared.Atmos.Components;
+
+[RegisterComponent, NetworkedComponent]
+public sealed class GasTileOverlayComponent : Component
+{
+    /// <summary>
+    ///     The tiles that have had their atmos data updated since last tick
+    /// </summary>
+    public readonly HashSet<Vector2i> InvalidTiles = new();
+
+    /// <summary>
+    ///     Gas data stored in chunks to make PVS / bubbling easier.
+    /// </summary>
+    public readonly Dictionary<Vector2i, GasOverlayChunk> Chunks = new();
+
+    /// <summary>
+    ///     Tick at which PVS was last toggled. Ensures that all players receive a full update when toggling PVS.
+    /// </summary>
+    public GameTick ForceTick { get; set; }
+}
+
+
+[Serializable, NetSerializable]
+public sealed class GasTileOverlayState : ComponentState, IComponentDeltaState
+{
+    public readonly Dictionary<Vector2i, GasOverlayChunk> Chunks;
+    public bool FullState => AllChunks == null;
+
+    // required to infer deleted/missing chunks for delta states
+    public HashSet<Vector2i>? AllChunks;
+
+    public GasTileOverlayState(Dictionary<Vector2i, GasOverlayChunk> chunks)
+    {
+        Chunks = chunks;
+    }
+
+    public void ApplyToFullState(ComponentState fullState)
+    {
+        DebugTools.Assert(!FullState);
+        var state = (GasTileOverlayState) fullState;
+        DebugTools.Assert(state.FullState);
+
+        foreach (var key in state.Chunks.Keys)
+        {
+            if (!AllChunks!.Contains(key))
+                state.Chunks.Remove(key);
+        }
+
+        foreach (var (chunk, data) in Chunks)
+        {
+            state.Chunks[chunk] = new(data);
+        }
+    }
+
+    public ComponentState CreateNewFullState(ComponentState fullState)
+    {
+        DebugTools.Assert(!FullState);
+        var state = (GasTileOverlayState) fullState;
+        DebugTools.Assert(state.FullState);
+
+        var chunks = new Dictionary<Vector2i, GasOverlayChunk>(state.Chunks.Count);
+
+        foreach (var (chunk, data) in Chunks)
+        {
+            chunks[chunk] = new(data);
+        }
+
+        foreach (var (chunk, data) in state.Chunks)
+        {
+            if (AllChunks!.Contains(chunk))
+                chunks.TryAdd(chunk, new(data));
+        }
+
+        return new GasTileOverlayState(chunks);
+    }
+}