Layering for atmospheric pipes (#36124)

Co-authored-by: ArtisticRoomba <145879011+ArtisticRoomba@users.noreply.github.com>
Co-authored-by: Kevin Zheng <kevinz5000@gmail.com>

Content.Server/Atmos/EntitySystems/AtmosPipeLayersSystem.cs

@@ -0,0 +1,77 @@
+using Content.Server.Atmos.Components;
+using Content.Server.NodeContainer.EntitySystems;
+using Content.Server.NodeContainer.NodeGroups;
+using Content.Server.NodeContainer.Nodes;
+using Content.Shared.Atmos.Components;
+using Content.Shared.Atmos.EntitySystems;
+using Content.Shared.Construction.Components;
+using Content.Shared.NodeContainer;
+using Content.Shared.Popups;
+
+namespace Content.Server.Atmos.EntitySystems;
+
+/// <summary>
+/// The system responsible for checking and adjusting the connection layering of gas pipes
+/// </summary>
+public sealed partial class AtmosPipeLayersSystem : SharedAtmosPipeLayersSystem
+{
+    [Dependency] private readonly NodeGroupSystem _nodeGroup = default!;
+    [Dependency] private readonly PipeRestrictOverlapSystem _pipeRestrictOverlap = default!;
+    [Dependency] private readonly SharedPopupSystem _popup = default!;
+    [Dependency] private readonly SharedTransformSystem _xform = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<AtmosPipeLayersComponent, ComponentInit>(OnInit);
+    }
+
+    private void OnInit(Entity<AtmosPipeLayersComponent> ent, ref ComponentInit args)
+    {
+        SetPipeLayer(ent, ent.Comp.CurrentPipeLayer);
+    }
+
+    /// <inheritdoc/>
+    public override void SetPipeLayer(Entity<AtmosPipeLayersComponent> ent, AtmosPipeLayer layer, EntityUid? user = null, EntityUid? used = null)
+    {
+        if (ent.Comp.PipeLayersLocked)
+            return;
+
+        base.SetPipeLayer(ent, layer);
+
+        if (!TryComp<NodeContainerComponent>(ent, out var nodeContainer))
+            return;
+
+        // Update the layer values of all pipe nodes associated with the entity
+        foreach (var (id, node) in nodeContainer.Nodes)
+        {
+            if (node is not PipeNode { } pipeNode)
+                continue;
+
+            if (pipeNode.CurrentPipeLayer == ent.Comp.CurrentPipeLayer)
+                continue;
+
+            pipeNode.CurrentPipeLayer = ent.Comp.CurrentPipeLayer;
+
+            if (pipeNode.NodeGroup != null)
+                _nodeGroup.QueueRemakeGroup((BaseNodeGroup)pipeNode.NodeGroup);
+        }
+
+        // If a user wasn't responsible for unanchoring the pipe, leave it be
+        if (user == null || used == null)
+            return;
+
+        // Unanchor the pipe if its new layer overlaps with another pipe
+        var xform = Transform(ent);
+
+        if (!HasComp<PipeRestrictOverlapComponent>(ent) || !_pipeRestrictOverlap.CheckOverlap((ent, nodeContainer, xform)))
+            return;
+
+        RaiseLocalEvent(ent, new BeforeUnanchoredEvent(user.Value, used.Value));
+        _xform.Unanchor(ent, xform);
+        RaiseLocalEvent(ent, new UserUnanchoredEvent(user.Value, used.Value));
+
+        _popup.PopupEntity(Loc.GetString("pipe-restrict-overlap-popup-blocked", ("pipe", ent)), ent, user.Value);
+    }
+}