NPC refactor (#10122)

Co-authored-by: metalgearsloth <metalgearsloth@gmail.com>

Content.IntegrationTests/Tests/NPC/NPCTest.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Content.Server.NPC.HTN;
+using NUnit.Framework;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Utility;
+
+namespace Content.IntegrationTests.Tests.NPC;
+
+[TestFixture]
+public sealed class NPCTest
+{
+    [Test]
+    public async Task CompoundRecursion()
+    {
+        var pool = await PoolManager.GetServerClient(new PoolSettings() { NoClient = true });
+        var server = pool.Pair.Server;
+
+        await server.WaitIdleAsync();
+
+        var protoManager = server.ResolveDependency<IPrototypeManager>();
+
+        await server.WaitAssertion(() =>
+        {
+            var counts = new Dictionary<string, int>();
+
+            foreach (var compound in protoManager.EnumeratePrototypes<HTNCompoundTask>())
+            {
+                Count(compound, counts);
+                counts.Clear();
+            }
+        });
+
+        await pool.CleanReturnAsync();
+    }
+
+    private static void Count(HTNCompoundTask compound, Dictionary<string, int> counts)
+    {
+        foreach (var branch in compound.Branches)
+        {
+            foreach (var task in branch.Tasks)
+            {
+                if (task is HTNCompoundTask compoundTask)
+                {
+                    var count = counts.GetOrNew(compound.ID);
+                    count++;
+
+                    Assert.That(count, Is.LessThan(50));
+                    counts[compound.ID] = count;
+                    Count(compoundTask, counts);
+                }
+            }
+        }
+    }
+}