Add multipart machines system (#35969)

Content.Client/Machines/EntitySystems/MultipartMachineSystem.cs

@@ -0,0 +1,109 @@
+using Content.Client.Examine;
+using Content.Client.Machines.Components;
+using Content.Shared.Machines.Components;
+using Content.Shared.Machines.EntitySystems;
+using Robust.Client.GameObjects;
+using Robust.Shared.Map;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Serialization.Manager;
+using Robust.Shared.Spawners;
+
+namespace Content.Client.Machines.EntitySystems;
+
+/// <summary>
+/// Client side handling of multipart machines.
+/// Handles client side examination events to show the expected layout of the machine
+/// based on the origin of the main entity.
+/// </summary>
+public sealed class MultipartMachineSystem : SharedMultipartMachineSystem
+{
+    private readonly EntProtoId _ghostPrototype = "MultipartMachineGhost";
+    private readonly Color _partiallyTransparent = new Color(255, 255, 255, 180);
+
+    [Dependency] private readonly SpriteSystem _sprite = default!;
+    [Dependency] private readonly IPrototypeManager _prototype = default!;
+    [Dependency] private readonly MetaDataSystem _metaData = default!;
+    [Dependency] private readonly ISerializationManager _serialization= default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<MultipartMachineComponent, ClientExaminedEvent>(OnMachineExamined);
+        SubscribeLocalEvent<MultipartMachineComponent, AfterAutoHandleStateEvent>(OnHandleState);
+        SubscribeLocalEvent<MultipartMachineGhostComponent, TimedDespawnEvent>(OnGhostDespawned);
+    }
+
+    /// <summary>
+    /// Handles spawning several ghost sprites to show where the different parts of the machine
+    /// should go and the rotations they're expected to have.
+    /// Can only show one set of ghost parts at a time and their location depends on the current map/grid
+    /// location of the origin machine.
+    /// </summary>
+    /// <param name="ent">Entity/Component that has been inspected.</param>
+    /// <param name="args">Args for the event.</param>
+    private void OnMachineExamined(Entity<MultipartMachineComponent> ent, ref ClientExaminedEvent args)
+    {
+        if (ent.Comp.Ghosts.Count != 0)
+        {
+            // Already showing some part ghosts
+            return;
+        }
+
+        foreach (var part in ent.Comp.Parts.Values)
+        {
+            if (part.Entity.HasValue)
+                continue;
+
+            var entityCoords = new EntityCoordinates(ent.Owner, part.Offset);
+            var ghostEnt = Spawn(_ghostPrototype, entityCoords);
+
+            if (!XformQuery.TryGetComponent(ghostEnt, out var xform))
+                break;
+
+            xform.LocalRotation = part.Rotation;
+
+            Comp<MultipartMachineGhostComponent>(ghostEnt).LinkedMachine = ent;
+
+            ent.Comp.Ghosts.Add(ghostEnt);
+
+            if (part.GhostProto == null)
+                continue;
+
+            var entProto = _prototype.Index(part.GhostProto.Value);
+            if (!entProto.Components.TryGetComponent("Sprite", out var s) || s is not SpriteComponent protoSprite)
+                return;
+
+            var ghostSprite = EnsureComp<SpriteComponent>(ghostEnt);
+            _serialization.CopyTo(protoSprite, ref ghostSprite, notNullableOverride: true);
+
+            _sprite.SetColor((ghostEnt, ghostSprite), _partiallyTransparent);
+
+            _metaData.SetEntityName(ghostEnt, entProto.Name);
+            _metaData.SetEntityDescription(ghostEnt, entProto.Description);
+        }
+    }
+
+    private void OnHandleState(Entity<MultipartMachineComponent> ent, ref AfterAutoHandleStateEvent args)
+    {
+        foreach (var part in ent.Comp.Parts.Values)
+        {
+            part.Entity = part.NetEntity.HasValue ? EnsureEntity<MultipartMachinePartComponent>(part.NetEntity.Value, ent) : null;
+        }
+    }
+
+    /// <summary>
+    /// Handles when a ghost part despawns after its short lifetime.
+    /// Will attempt to remove itself from the list of known ghost entities in the main multipart
+    /// machine component.
+    /// </summary>
+    /// <param name="ent">Ghost entity that has been despawned.</param>
+    /// <param name="args">Args for the event.</param>
+    private void OnGhostDespawned(Entity<MultipartMachineGhostComponent> ent, ref TimedDespawnEvent args)
+    {
+        if (!TryComp<MultipartMachineComponent>(ent.Comp.LinkedMachine, out var machine))
+            return;
+
+        machine.Ghosts.Remove(ent);
+    }
+}