Refactor timelines and season creation logic into World

MultiversalDiplomacy/Adjudicate/MovementPhaseAdjudicator.cs

@@ -312,9 +312,9 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
 
         // All moves to a particular season in a single phase result in the same future. Keep a
         // record of when a future season has been created.
-        Dictionary<Season, Season> createdFutures = new();
+        Dictionary<Season, Season> createdFutures = [];
-        List<Unit> createdUnits = new();
+        List<Unit> createdUnits = [];
-        List<RetreatingUnit> retreats = new();
+        List<RetreatingUnit> retreats = [];
 
         // Populate createdFutures with the timeline fork decisions
         logger.Log(1, "Processing AdvanceTimeline decisions");
@@ -324,9 +324,7 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
             if (advanceTimeline.Outcome == true)
             {
                 // A timeline that doesn't have a future yet simply continues. Otherwise, it forks.
-                createdFutures[advanceTimeline.Season] = !world.GetFutures(advanceTimeline.Season).Any()
+                createdFutures[advanceTimeline.Season] = world.ContinueOrFork(advanceTimeline.Season);
-                    ? advanceTimeline.Season.MakeNext()
-                    : advanceTimeline.Season.MakeFork();
             }
         }
 

MultiversalDiplomacy/Model/ModelExtensions.cs

@@ -20,4 +20,10 @@ public static class ModelExtensions
     {
         return $"{coord.season.Timeline}-{coord.province.Abbreviations[0]}@{coord.season.Turn}";
     }
+
+    public static World ContinueOrFork(this World world, Season season, out Season future)
+    {
+        future = world.ContinueOrFork(season);
+        return world.Update(seasons: world.Seasons.Append(future));
+    }
 }

MultiversalDiplomacy/Model/Season.cs

@@ -43,44 +43,12 @@ public class Season
     [JsonIgnore]
     public (string Timeline, int Turn) Coord => (this.Timeline, this.Turn);
 
-    /// <summary>
+    public Season(string? past, int turn, string timeline)
-    /// The shared timeline number generator.
-    /// </summary>
-    [JsonIgnore]
-    private TimelineFactory Timelines { get; }
-
-    private Season(string? past, int turn, string timeline, TimelineFactory factory)
     {
         this.Past = past;
         this.Turn = turn;
         this.Timeline = timeline;
-        this.Timelines = factory;
     }
 
     public override string ToString() => Designation;
-
-    /// <summary>
-    /// Create a root season at the beginning of time.
-    /// </summary>
-    public static Season MakeRoot()
-    {
-        TimelineFactory factory = new();
-        return new Season(
-            past: null,
-            turn: FIRST_TURN,
-            timeline: factory.NextTimeline(),
-            factory: factory);
-    }
-
-    /// <summary>
-    /// Create a season immediately after this one in the same timeline.
-    /// </summary>
-    public Season MakeNext()
-        => new(this.Designation, Turn + 1, Timeline, Timelines);
-
-    /// <summary>
-    /// Create a season immediately after this one in a new timeline.
-    /// </summary>
-    public Season MakeFork()
-        => new(this.Designation, Turn + 1, Timelines.NextTimeline(), Timelines);
 }

MultiversalDiplomacy/Model/TimelineFactory.cs

@@ -3,7 +3,7 @@ namespace MultiversalDiplomacy.Model;
 /// <summary>
 /// A shared counter for handing out new timeline designations.
 /// </summary>
-internal class TimelineFactory
+public class TimelineFactory
 {
     private static readonly char[] Letters = [
         'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',

MultiversalDiplomacy/Model/World.cs

@@ -63,6 +63,11 @@ public class World
     /// </summary>
     public ReadOnlyDictionary<string, OrderHistory> OrderHistory { get; }
 
+    /// <summary>
+    /// The shared timeline number generator.
+    /// </summary>
+    public TimelineFactory Timelines { get; }
+
     /// <summary>
     /// Immutable game options.
     /// </summary>
@@ -77,6 +82,7 @@ public class World
         ReadOnlyCollection<Unit> units,
         ReadOnlyCollection<RetreatingUnit> retreatingUnits,
         ReadOnlyDictionary<string, OrderHistory> orderHistory,
+        TimelineFactory timelines,
         Options options)
     {
         this.Map = map;
@@ -84,6 +90,7 @@ public class World
         this.Units = units;
         this.RetreatingUnits = retreatingUnits;
         this.OrderHistory = orderHistory;
+        this.Timelines = timelines;
         this.Options = options;
 
         this.SeasonLookup = new(Seasons.ToDictionary(season => $"{season.Timeline}{season.Turn}"));
@@ -105,6 +112,7 @@ public class World
             units ?? previous.Units,
             retreatingUnits ?? previous.RetreatingUnits,
             orderHistory ?? previous.OrderHistory,
+            previous.Timelines,
             options ?? previous.Options)
     {
     }
@@ -114,12 +122,14 @@ public class World
     /// </summary>
     public static World WithMap(Map map)
     {
+        TimelineFactory timelines = new();
         return new World(
             map,
-            new([Season.MakeRoot()]),
+            new([new(past: null, Season.FIRST_TURN, timelines.NextTimeline())]),
             new([]),
             new([]),
             new(new Dictionary<string, OrderHistory>()),
+            timelines,
             new Options());
     }
 
@@ -209,21 +219,12 @@ public class World
     }
 
     /// <summary>
-    /// Create a season immediately after this one in the same timeline.
+    /// Create a continuation of this season if it has no futures, otherwise ceate a fork.
     /// </summary>
-    public World ContinueSeason(string season)
+    public Season ContinueOrFork(Season season)
-        => Update(seasons: Seasons.Append(SeasonLookup[season].MakeNext()));
+        => GetFutures(season).Any()
-
+        ? new(season.Designation, season.Turn + 1, Timelines.NextTimeline())
-    /// <summary>
+        : new(season.Designation, season.Turn + 1, season.Timeline);
-    /// Create a season immediately after this one in the same timeline.
-    /// </summary>
-    public World ContinueSeason(Season season) => ContinueSeason(season.ToString());
-
-    /// <summary>
-    /// Create a season immediately after this one in a new timeline.
-    /// </summary>
-    public World ForkSeason(string season)
-        => Update(seasons: Seasons.Append(SeasonLookup[season].MakeFork()));
 
     /// <summary>
     /// A standard Diplomacy game setup.

MultiversalDiplomacyTests/SeasonTests.cs

@@ -9,30 +9,22 @@ public class SeasonTests
     [Test]
     public void TimelineForking()
     {
-        World world = World
+        World world = World.WithMap(Map.Test);
-            .WithMap(Map.Test)
+        Season a0 = world.GetSeason("a0");
-            .ContinueSeason("a0")
+        world = world
-            .ContinueSeason("a1")
+            .ContinueOrFork(a0, out Season a1)
-            .ContinueSeason("a2")
+            .ContinueOrFork(a1, out Season a2)
-            .ForkSeason("a1")
+            .ContinueOrFork(a2, out Season a3)
-            .ContinueSeason("b2")
+            .ContinueOrFork(a1, out Season b2)
-            .ForkSeason("a1")
+            .ContinueOrFork(b2, out Season b3)
-            .ForkSeason("a2");
+            .ContinueOrFork(a1, out Season c2)
+            .ContinueOrFork(a2, out Season d3);
 
         Assert.That(
             world.Seasons.Select(season => season.ToString()),
             Is.EquivalentTo(new List<string> { "a0", "a1", "a2", "a3", "b2", "b3", "c2", "d3" }),
             "Unexpected seasons");
 
-        Season a0 = world.GetSeason("a0");
-        Season a1 = world.GetSeason("a1");
-        Season a2 = world.GetSeason("a2");
-        Season a3 = world.GetSeason("a3");
-        Season b2 = world.GetSeason("b2");
-        Season b3 = world.GetSeason("b3");
-        Season c2 = world.GetSeason("c2");
-        Season d3 = world.GetSeason("d3");
-
         Assert.That(a0.Timeline, Is.EqualTo("a"), "Unexpected trunk timeline");
         Assert.That(a1.Timeline, Is.EqualTo("a"), "Unexpected trunk timeline");
         Assert.That(a2.Timeline, Is.EqualTo("a"), "Unexpected trunk timeline");

MultiversalDiplomacyTests/UnitTests.cs

@@ -17,12 +17,10 @@ public class UnitTests
         Season a0 = world.RootSeason;
         Unit u1 = Unit.Build(Mun, a0, pw1, UnitType.Army);
 
-        world = world.ContinueSeason(a0);
+        world = world.ContinueOrFork(a0, out Season a1);
-        Season a1 = world.GetSeason("a1");
         Unit u2 = u1.Next(Boh, a1);
 
-        world = world.ContinueSeason(a1);
+        _ = world.ContinueOrFork(a1, out Season a2);
-        Season a2 = world.GetSeason("a2");
         Unit u3 = u2.Next(Tyr, a2);
 
         Assert.That(u3.Past, Is.EqualTo(u2), "Missing unit past");