Adds support for a map rotation system. (#7162)

* Adds support for a map rotation system.
It is now the default way of selecting a map, map votes have been disabled.

* whoops

* Randomize the map it starts off with, too.
(it'd pick bagel every time otherwise)

* Address review

* remove knight from rotation due to it being an unmaintained map.

* minor cleanup

Content.Server/Maps/GameMapManager.cs

@@ -22,8 +22,11 @@ public sealed class GameMapManager : IGameMapManager
     [Dependency] private readonly IRobustRandom _random = default!;
     [Dependency] private readonly IChatManager _chatManager = default!;
 
+    private readonly Queue<string> _previousMaps = new Queue<string>();
     private GameMapPrototype _currentMap = default!;
     private bool _currentMapForced;
+    private bool _mapRotationEnabled;
+    private int _mapQueueDepth = 1;
 
     public void Initialize()
     {
@@ -35,6 +38,25 @@ public sealed class GameMapManager : IGameMapManager
                 throw new ArgumentException($"Unknown map prototype {value} was selected!");
         }, true);
         _configurationManager.OnValueChanged(CCVars.GameMapForced, value => _currentMapForced = value, true);
+        _configurationManager.OnValueChanged(CCVars.GameMapRotation, value => _mapRotationEnabled = value, true);
+        _configurationManager.OnValueChanged(CCVars.GameMapMemoryDepth, value =>
+        {
+            _mapQueueDepth = value;
+            // Drain excess.
+            while (_previousMaps.Count > _mapQueueDepth)
+            {
+                _previousMaps.Dequeue();
+            }
+        }, true);
+
+        var maps = AllVotableMaps().ToArray();
+        _random.Shuffle(maps);
+        foreach (var map in maps)
+        {
+            if (_previousMaps.Count >= _mapQueueDepth)
+                break;
+            _previousMaps.Enqueue(map.ID);
+        }
     }
 
     public IEnumerable<GameMapPrototype> CurrentlyEligibleMaps()
@@ -75,17 +97,18 @@ public sealed class GameMapManager : IGameMapManager
     public void SelectRandomMap()
     {
         var maps = CurrentlyEligibleMaps().ToList();
-        _random.Shuffle(maps);
-        _currentMap = maps[0];
+        _currentMap = _random.Pick(maps);
         _currentMapForced = false;
     }
 
     public GameMapPrototype GetSelectedMap()
     {
-        return _currentMap;
+        if (!_mapRotationEnabled || _currentMapForced)
+            return _currentMap;
+        return SelectMapInQueue() ?? CurrentlyEligibleMaps().First();
     }
 
-    public GameMapPrototype GetSelectedMapChecked(bool loud = false)
+    public GameMapPrototype GetSelectedMapChecked(bool loud = false, bool markAsPlayed = false)
     {
         if (!_currentMapForced && !IsMapEligible(GetSelectedMap()))
         {
@@ -100,7 +123,11 @@ public sealed class GameMapManager : IGameMapManager
             }
         }
 
-        return GetSelectedMap();
+        var map = GetSelectedMap();
+
+        if (markAsPlayed)
+            _previousMaps.Enqueue(map.ID);
+        return map;
     }
 
     public bool CheckMapExists(string gameMap)
@@ -127,4 +154,39 @@ public sealed class GameMapManager : IGameMapManager
         else
             return gameMap.MapName;
     }
+
+    public int GetMapQueuePriority(string gameMapProtoName)
+    {
+        var i = 0;
+        foreach (var map in _previousMaps.Reverse())
+        {
+            if (map == gameMapProtoName)
+                return i;
+            i++;
+        }
+
+        return _mapQueueDepth;
+    }
+
+    public GameMapPrototype? SelectMapInQueue()
+    {
+        var eligible = CurrentlyEligibleMaps()
+            .Where(x => x.Votable)
+            .Select(x => (proto: x, weight: GetMapQueuePriority(x.ID)))
+            .OrderByDescending(x => x.weight).ToArray();
+        if (eligible.Length is 0)
+            return null;
+
+        var weight = eligible[0].weight;
+        return eligible.Where(x => x.Item2 == weight).OrderBy(x => x.proto.ID).First().proto;
+    }
+
+    private void EnqueueMap(string mapProtoName)
+    {
+        _previousMaps.Enqueue(mapProtoName);
+        while (_previousMaps.Count > _mapQueueDepth)
+        {
+            _previousMaps.Dequeue();
+        }
+    }
 }