Delta-v/Content.Client/Atmos/EntitySystems/GasTileOverlaySystem.cs

using Content.Shared.Atmos;
using Content.Shared.Atmos.Components;
using Content.Shared.Atmos.EntitySystems;
using JetBrains.Annotations;
using Robust.Shared.GameStates;

namespace Content.Client.Atmos.EntitySystems;

[UsedImplicitly]
public sealed class GasTileOverlaySystem : SharedGasTileOverlaySystem
{
    public override void Initialize()
    {
        base.Initialize();
        SubscribeNetworkEvent<GasOverlayUpdateEvent>(HandleGasOverlayUpdate);
        SubscribeLocalEvent<GasTileOverlayComponent, ComponentHandleState>(OnHandleState);
    }

    private void OnHandleState(EntityUid gridUid, GasTileOverlayComponent comp, ref ComponentHandleState args)
    {
        Dictionary<Vector2i, GasOverlayChunk> modifiedChunks;

        switch (args.Current)
        {
            // is this a delta or full state?
            case GasTileOverlayDeltaState delta:
            {
                modifiedChunks = delta.ModifiedChunks;
                foreach (var index in comp.Chunks.Keys)
                {
                    if (!delta.AllChunks.Contains(index))
                        comp.Chunks.Remove(index);
                }

                break;
            }
            case GasTileOverlayState state:
            {
                modifiedChunks = state.Chunks;
                foreach (var index in comp.Chunks.Keys)
                {
                    if (!state.Chunks.ContainsKey(index))
                        comp.Chunks.Remove(index);
                }

                break;
            }
            default:
                return;
        }

        foreach (var (index, data) in modifiedChunks)
        {
            comp.Chunks[index] = data;
        }
    }

    private void HandleGasOverlayUpdate(GasOverlayUpdateEvent ev)
    {
        foreach (var (nent, removedIndicies) in ev.RemovedChunks)
        {
            var grid = GetEntity(nent);

            if (!TryComp(grid, out GasTileOverlayComponent? comp))
                continue;

            foreach (var index in removedIndicies)
            {
                comp.Chunks.Remove(index);
            }
        }

        foreach (var (nent, gridData) in ev.UpdatedChunks)
        {
            var grid = GetEntity(nent);

            if (!TryComp(grid, out GasTileOverlayComponent? comp))
                continue;

            foreach (var chunkData in gridData)
            {
                comp.Chunks[chunkData.Index] = chunkData;
            }
        }
    }
}