Remove Unit.Past

Past is only used in tests. It was added speculatively in expectation that it would be useful for clients. Removing this means that all the fields of a Unit are present in the key, so the key can uniquely determine the Unit or even be parsed into one, and therefore multiple Unit instances can be equivalent if their fields match. If unit pasts are useful later, they can be tracked extrinsically the way timelines are tracked.

MultiversalDiplomacy/Adjudicate/Decision/MovementDecisions.cs

@@ -94,7 +94,7 @@ public class MovementDecisions
             .ToList();
 
         (string province, string season) UnitPoint(Unit unit)
-            => (world.Map.GetLocation(unit.Location).Province.Name, unit.Season.Key);
+            => (unit.GetProvince(world).Name, unit.Season.Key);
         (string province, string season) MovePoint(MoveOrder move)
             => (SplitKey(move.Location).province, move.Season.Key);
 
@@ -102,7 +102,7 @@ public class MovementDecisions
         foreach (UnitOrder order in relevantOrders)
         {
             HoldStrength[UnitPoint(order.Unit)] = new(
-                world.Map.GetLocation(order.Unit.Location).Province,
+                order.Unit.GetProvince(world),
                 order.Unit.Season,
                 order);
         }
@@ -110,7 +110,7 @@ public class MovementDecisions
         bool IsIncoming(UnitOrder me, MoveOrder other)
             => me != other
             && other.Season == me.Unit.Season
-            && SplitKey(other.Location).province == world.Map.GetLocation(me.Unit).Province.Name;
+            && SplitKey(other.Location).province == me.Unit.GetProvince(world).Name;
 
         bool IsSupportFor(SupportMoveOrder me, MoveOrder move)
             => me.Target.Key == move.Unit.Key
@@ -120,8 +120,8 @@ public class MovementDecisions
         bool AreOpposing(MoveOrder one, MoveOrder two)
             => one.Season == two.Unit.Season
             && two.Season == one.Unit.Season
-            && SplitKey(one.Location).province == world.Map.GetLocation(two.Unit).Province.Name
+            && SplitKey(one.Location).province == two.Unit.GetProvince(world).Name
-            && SplitKey(two.Location).province == world.Map.GetLocation(one.Unit).Province.Name;
+            && SplitKey(two.Location).province == one.Unit.GetProvince(world).Name;
 
         bool AreCompeting(MoveOrder one, MoveOrder two)
             => one != two
@@ -174,7 +174,7 @@ public class MovementDecisions
 
                 // Ensure a hold strength decision exists for the target's province.
                 HoldStrength.Ensure(UnitPoint(support.Target), () => new(
-                    world.Map.GetLocation(support.Target.Location).Province,
+                    support.Target.GetProvince(world),
                     support.Target.Season));
 
                 if (support is SupportHoldOrder supportHold)

MultiversalDiplomacy/Adjudicate/MovementPhaseAdjudicator.cs

@@ -92,7 +92,7 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
         ILookup<bool, MoveOrder> moveOrdersByAdjacency = moveOrders
             .ToLookup(order =>
                 // Map adjacency
-                world.Map.GetLocation(order.Unit).Adjacents.Select(loc => loc.Key).Contains(order.Location)
+                order.Unit.GetLocation(world).Adjacents.Select(loc => loc.Key).Contains(order.Location)
                 // Turn adjacency
                 && Math.Abs(order.Unit.Season.Turn - order.Season.Turn) <= 1
                 // Timeline adjacency
@@ -177,8 +177,8 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
         AdjudicatorHelpers.InvalidateIfNotMatching(
             order =>
                 // Map adjacency with respect to province
-                world.Map.GetLocation(order.Unit).Adjacents.Any(
+                order.Unit.GetLocation(world).Adjacents.Any(
-                    adjLocation => adjLocation.Province == world.Map.GetLocation(order.Target).Province)
+                    adjLocation => adjLocation.Province == order.Target.GetLocation(world).Province)
                 // Turn adjacency
                 && Math.Abs(order.Unit.Season.Turn - order.Target.Season.Turn) <= 1
                 // Timeline adjacency
@@ -197,7 +197,7 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
         // Support-move orders are invalid if the unit supports a move to any location in its own
         // province.
         AdjudicatorHelpers.InvalidateIfNotMatching(
-            order => world.Map.GetLocation(order.Unit).Province != order.Province,
+            order => order.Unit.GetProvince(world) != order.Province,
             ValidationReason.NoSupportMoveAgainstSelf,
             ref supportMoveOrders,
             ref validationResults);
@@ -209,7 +209,7 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
         AdjudicatorHelpers.InvalidateIfNotMatching(
             order =>
                 // Map adjacency with respect to province
-                world.Map.GetLocation(order.Unit).Adjacents.Any(
+                order.Unit.GetLocation(world).Adjacents.Any(
                     adjLocation => adjLocation.Province == order.Province)
                 // Turn adjacency
                 && Math.Abs(order.Unit.Season.Turn - order.Season.Turn) <= 1
@@ -370,7 +370,7 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
             if (isDislodged.Outcome == false)
             {
                 // Non-dislodged units continue into the future.
-                Unit next = order.Unit.Next(world.Map.GetLocation(order.Unit).Key, future);
+                Unit next = order.Unit.Next(order.Unit.GetLocation(world).Key, future);
                 logger.Log(3, "Advancing unit to {0}", next);
                 createdUnits.Add(next);
             }
@@ -379,7 +379,7 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
                 // Create a retreat for each dislodged unit.
                 // TODO check valid retreats and disbands
                 logger.Log(3, "Creating retreat for {0}", order.Unit);
-                var validRetreats = world.Map.GetLocation(order.Unit).Adjacents
+                var validRetreats = order.Unit.GetLocation(world).Adjacents
                     .Select(loc => (future, loc))
                     .ToList();
                 RetreatingUnit retreat = new(order.Unit, validRetreats);
@@ -640,7 +640,7 @@ public class MovementPhaseAdjudicator : IPhaseAdjudicator
 
         // If the origin and destination are adjacent, then there is a path.
         if (// Map adjacency
-            world.Map.GetLocation(decision.Order.Unit).Adjacents.Select(loc => loc.Key).Contains(decision.Order.Location)
+            decision.Order.Unit.GetLocation(world).Adjacents.Select(loc => loc.Key).Contains(decision.Order.Location)
             // Turn adjacency
             && Math.Abs(decision.Order.Unit.Season.Turn - decision.Order.Season.Turn) <= 1
             // Timeline adjacency

MultiversalDiplomacy/Adjudicate/PathFinder.cs

@@ -12,7 +12,7 @@ public static class PathFinder
     /// Determines if a convoy path exists for a move in a convoy order.
     /// </summary>
     public static bool ConvoyPathExists(World world, ConvoyOrder order)
-        => ConvoyPathExists(world, world.Map.GetLocation(order.Target), order.Location, order.Season);
+        => ConvoyPathExists(world, order.Target.GetLocation(world), order.Location, order.Season);
 
     /// <summary>
     /// Determines if a convoy path exists for a move order.
@@ -20,7 +20,7 @@ public static class PathFinder
     public static bool ConvoyPathExists(World world, MoveOrder order)
         => ConvoyPathExists(
             world,
-            world.Map.GetLocation(order.Unit),
+            order.Unit.GetLocation(world),
             world.Map.GetLocation(order.Location),
             order.Season);
 

MultiversalDiplomacy/Model/Map.cs

@@ -72,9 +72,6 @@ public class Map
     public Location GetLocation(string designation)
         => LocationLookup[designation];
 
-    public Location GetLocation(Unit unit)
-        => GetLocation(unit.Location);
-
     /// <summary>
     /// Get the sole land location of a province.
     /// </summary>

MultiversalDiplomacy/Model/OrderParser.cs

@@ -259,7 +259,7 @@ public class OrderParser(World world)
         // and the location is ignored. This also satisfies DATC 4.B.5, which requires that a wrong coast for the
         // subject be ignored.
         subject = world.Units.FirstOrDefault(unit
-            => world.Map.GetLocation(unit!.Location).ProvinceName == province.Name
+            => unit!.GetProvince(world).Name == province.Name
             && unit!.Season.Timeline == timeline
             && unit!.Season.Turn == turn,
             null);
@@ -338,7 +338,7 @@ public class OrderParser(World world)
         // If the order location didn't disambiguate the coasts, either because it's missing or it's nonsense, the
         // order can be disambiguated by there being one accessible coast from the order source.
         if (destLocationKey is null) {
-            Location source = world.Map.GetLocation(subject.Location);
+            Location source = subject.GetLocation(world);
             var accessibleLocations = destProvince.Locations.Where(loc => loc.Adjacents.Contains(source));
             if (accessibleLocations.Count() == 1) destLocationKey ??= accessibleLocations.Single().Key;
         }
@@ -434,7 +434,7 @@ public class OrderParser(World world)
         // If the order location didn't disambiguate the coasts, either because it's missing or it's nonsense, the
         // order can be disambiguated by there being one accessible coast from the order source.
         if (destLocationKey is null) {
-            Location source = world.Map.GetLocation(target.Location);
+            Location source = target.GetLocation(world);
             var accessibleLocations = destProvince.Locations.Where(loc => loc.Adjacents.Contains(source));
             if (accessibleLocations.Count() == 1) destLocationKey ??= accessibleLocations.Single().Key;
         }

MultiversalDiplomacy/Model/Unit.cs

@@ -7,11 +7,6 @@ namespace MultiversalDiplomacy.Model;
 /// </summary>
 public class Unit
 {
-    /// <summary>
-    /// The previous iteration of a unit. This is null if the unit was just built.
-    /// </summary>
-    public string? Past { get; }
-
     /// <summary>
     /// The location on the map where the unit is.
     /// </summary>
@@ -38,9 +33,8 @@ public class Unit
     [JsonIgnore]
     public string Key => $"{Type.ToShort()} {Season.Timeline}-{Location}@{Season.Turn}";
 
-    public Unit(string? past, string location, Season season, string power, UnitType type)
+    public Unit(string location, Season season, string power, UnitType type)
     {
-        this.Past = past;
         this.Location = location;
         this.Season = season;
         this.Power = power;
@@ -55,11 +49,15 @@ public class Unit
     /// method after accepting a build order.
     /// </summary>
     public static Unit Build(string location, Season season, string power, UnitType type)
-        => new(past: null, location, season, power, type);
+        => new(location, season, power, type);
 
     /// <summary>
     /// Advance this unit's timeline to a new location and season.
     /// </summary>
     public Unit Next(string location, Season season)
-        => new(past: this.Key, location, season, this.Power, this.Type);
+        => new(location, season, this.Power, this.Type);
+
+    public Location GetLocation(World world) => world.Map.GetLocation(Location);
+
+    public Province GetProvince(World world) => GetLocation(world).Province;
 }

MultiversalDiplomacy/Model/World.cs

@@ -231,7 +231,7 @@ public class World
         Province province = Map.GetProvince(provinceName);
         season ??= Season.First;
         Unit? foundUnit = this.Units.SingleOrDefault(
-            u => Map.GetLocation(u!).Province == province && u!.Season == season,
+            u => u!.GetProvince(this) == province && u!.Season == season,
             null)
             ?? throw new KeyNotFoundException($"Unit at {province} at {season} not found");
         return foundUnit;

MultiversalDiplomacy/Script/AdjudicationQueryScriptHandler.cs

@@ -100,7 +100,7 @@ public class AdjudicationQueryScriptHandler(
                     => val.Valid
                     && val.Order is HoldOrder hold
                     && hold.Unit.Season == season
-                    && World.Map.GetLocation(hold.Unit.Location).ProvinceName == province.Name);
+                    && hold.Unit.GetProvince(World).Name == province.Name);
                 if (!matchingHolds.Any()) return ScriptResult.Fail("No matching holds");
 
                 return ScriptResult.Succeed(this);
@@ -129,7 +129,7 @@ public class AdjudicationQueryScriptHandler(
                 var matching = Validations.Where(val
                     => val.Order is UnitOrder order
                     && order.Unit.Season == season
-                    && World.Map.GetLocation(order.Unit.Location).ProvinceName == province.Name);
+                    && order.Unit.GetProvince(World).Name == province.Name);
                 if (!matching.Any()) return ScriptResult.Fail("No matching validations");
 
                 if (args[0] == "order-valid" && !matching.First().Valid) {
@@ -181,7 +181,7 @@ public class AdjudicationQueryScriptHandler(
                 var matchingDislodges = Adjudications.Where(adj
                     => adj is IsDislodged dislodge
                     && dislodge.Order.Unit.Season == season
-                    && World.Map.GetLocation(dislodge.Order.Unit.Location).ProvinceName == province.Name);
+                    && dislodge.Order.Unit.GetProvince(World).Name == province.Name);
                 if (!matchingDislodges.Any()) return ScriptResult.Fail("No matching dislodge decisions");
                 var isDislodged = matchingDislodges.Cast<IsDislodged>().First();
 
@@ -219,7 +219,7 @@ public class AdjudicationQueryScriptHandler(
                 var matchingMoves = Adjudications.Where(adj
                     => adj is DoesMove moves
                     && moves.Order.Unit.Season == season
-                    && World.Map.GetLocation(moves.Order.Unit.Location).ProvinceName == province.Name);
+                    && moves.Order.Unit.GetProvince(World).Name == province.Name);
                 if (!matchingMoves.Any()) return ScriptResult.Fail("No matching movement decisions");
                 var doesMove = matchingMoves.Cast<DoesMove>().First();
 
@@ -257,7 +257,7 @@ public class AdjudicationQueryScriptHandler(
                 var matchingSupports = Adjudications.Where(adj
                     => adj is GivesSupport sup
                     && sup.Order.Unit.Season == season
-                    && World.Map.GetLocation(sup.Order.Unit.Location).ProvinceName == province.Name);
+                    && sup.Order.Unit.GetProvince(World).Name == province.Name);
                 if (!matchingSupports.Any()) return ScriptResult.Fail("No matching support decisions");
                 var supports = matchingSupports.Cast<GivesSupport>().First();
 

MultiversalDiplomacyTests/MDATC_A.cs

@@ -47,12 +47,9 @@ public class TimeTravelTest
         Unit originalUnit = world.GetUnitAt("Mun", s0);
         Unit aMun0 = world.GetUnitAt("Mun", s1);
         Unit aTyr = world.GetUnitAt("Tyr", fork);
-        Assert.That(aTyr.Past, Is.EqualTo(mun1.Order.Unit.Key));
-        Assert.That(world.GetUnitByKey(aTyr.Past!).Past, Is.EqualTo(mun0.Order.Unit.Key));
 
         // Confirm that there is a unit in Mun b1 originating from Mun a0
         Unit aMun1 = world.GetUnitAt("Mun", fork);
-        Assert.That(aMun1.Past, Is.EqualTo(originalUnit.Key));
     }
 
     [Test]
@@ -94,10 +91,6 @@ public class TimeTravelTest
         World world = setup.UpdateWorld();
         Season fork = new("b1");
         Unit tyr1 = world.GetUnitAt("Tyr", fork);
-        Assert.That(
-            tyr1.Past,
-            Is.EqualTo(mun0.Order.Unit.Key),
-            "Expected A Mun a0 to advance to Tyr b1");
         Assert.That(
             world.RetreatingUnits.Count,
             Is.EqualTo(1),

MultiversalDiplomacyTests/MovementAdjudicatorTest.cs

@@ -171,7 +171,7 @@ public class MovementAdjudicatorTest
 
         // Confirm the unit was created
         Assert.That(updated.Units.Count, Is.EqualTo(2));
-        Unit second = updated.Units.Single(u => u.Past != null);
+        Unit second = updated.Units.OrderBy(u => -u.Season.Turn).First();
         Assert.That(second.Location, Is.EqualTo(mun.Order.Unit.Location));
         Assert.That(second.Season.Timeline, Is.EqualTo(mun.Order.Unit.Season.Timeline));
 
@@ -208,7 +208,6 @@ public class MovementAdjudicatorTest
         Unit u2 = updated.GetUnitAt("Mun", s2);
         Assert.That(updated.Units.Count, Is.EqualTo(2));
         Assert.That(u2.Key, Is.Not.EqualTo(mun1.Order.Unit.Key));
-        Assert.That(u2.Past, Is.EqualTo(mun1.Order.Unit.Key));
         Assert.That(u2.Season, Is.EqualTo(s2));
 
         setup[("a", 1)]
@@ -228,7 +227,6 @@ public class MovementAdjudicatorTest
         updated = setup.UpdateWorld();
         Season s3 = new(s2.Timeline, s2.Turn + 1);
         Unit u3 = updated.GetUnitAt("Mun", s3);
-        Assert.That(u3.Past, Is.EqualTo(mun2.Order.Unit.Key));
     }
 
     [Test]
@@ -258,7 +256,6 @@ public class MovementAdjudicatorTest
         Unit u2 = updated.GetUnitAt("Tyr", s2);
         Assert.That(updated.Units.Count, Is.EqualTo(2));
         Assert.That(u2.Key, Is.Not.EqualTo(mun1.Order.Unit.Key));
-        Assert.That(u2.Past, Is.EqualTo(mun1.Order.Unit.Key));
         Assert.That(u2.Season, Is.EqualTo(s2));
 
         setup[("a", 1)]
@@ -278,6 +275,5 @@ public class MovementAdjudicatorTest
         updated = setup.UpdateWorld();
         Season s3 = new(s2.Timeline, s2.Turn + 1);
         Unit u3 = updated.GetUnitAt("Mun", s3);
-        Assert.That(u3.Past, Is.EqualTo(u2.Key));
     }
 }

MultiversalDiplomacyTests/OrderReference.cs

@@ -108,7 +108,7 @@ public abstract class OrderReference
                 DefendStrength defend => defend.Order == this.Order,
                 PreventStrength prevent => prevent.Order == this.Order,
                 HoldStrength hold => this.Order is UnitOrder unitOrder
-                    && hold.Province == Builder.World.Map.GetLocation(unitOrder.Unit).Province,
+                    && hold.Province == unitOrder.Unit.GetProvince(Builder.World),
                 _ => false,
             }).ToList();
             return adjudications;

MultiversalDiplomacyTests/SerializationTest.cs

@@ -133,10 +133,6 @@ public class SerializationTest
         World world = setup.UpdateWorld();
         Season fork = new("b1");
         Unit tyr1 = world.GetUnitAt("Tyr", fork);
-        Assert.That(
-            tyr1.Past,
-            Is.EqualTo(mun0.Order.Unit.Key),
-            "Expected A Mun a0 to advance to Tyr b1");
         Assert.That(
             world.RetreatingUnits.Count,
             Is.EqualTo(1),

MultiversalDiplomacyTests/TestCaseBuilder.cs

@@ -263,7 +263,7 @@ public class TestCaseBuilder
         foreach (Unit unit in this.World.Units)
         {
             if (unit.Power == power
-                && World.Map.GetLocation(unit).Province == location.Province
+                && unit.GetProvince(World) == location.Province
                 && unit.Season == season)
             {
                 return unit;

MultiversalDiplomacyTests/TestCaseBuilderTest.cs

@@ -68,7 +68,7 @@ class TestCaseBuilderTest
         List<UnitOrder> orders = setup.Orders.OfType<UnitOrder>().ToList();
 
         Func<UnitOrder, bool> OrderForProvince(string name)
-            => order => setup.World.Map.GetLocation(order.Unit).Province.Name == name;
+            => order => order.Unit.GetProvince(setup.World).Name == name;
 
         UnitOrder orderBer = orders.Single(OrderForProvince("Berlin"));
         Assert.That(orderBer, Is.InstanceOf<MoveOrder>(), "Unexpected order type");

MultiversalDiplomacyTests/UnitTests.cs

@@ -22,10 +22,6 @@ public class UnitTests
         _ = world.WithNewSeason(a1, out Season a2);
         Unit u3 = u2.Next(Tyr.Key, a2);
 
-        Assert.That(u3.Past, Is.EqualTo(u2.Key), "Missing unit past");
-        Assert.That(u2.Past, Is.EqualTo(u1.Key), "Missing unit past");
-        Assert.That(u1.Past, Is.Null, "Unexpected unit past");
-
         Assert.That(u1.Season, Is.EqualTo(a0), "Unexpected unit season");
         Assert.That(u2.Season, Is.EqualTo(a1), "Unexpected unit season");
         Assert.That(u3.Season, Is.EqualTo(a2), "Unexpected unit season");