Add probabilistic branching helper

07_Basketball/csharp/Game.cs

@@ -32,16 +32,16 @@ internal class Game
         while (true)
         {
             _io.WriteLine("Center jump");
-            scoreboard.Offense = ContestBall(0.4f, scoreboard, "{0} controls the tap");
+            ContestBall(0.4f, scoreboard, "{0} controls the tap");
 
             _io.WriteLine();
 
-            do
+            while (scoreboard.Offense is not null)
             {
                 var gameOver = scoreboard.Offense.ResolvePlay(scoreboard);
                 if (gameOver) { return; }
                 if (clock.IsHalfTime) { scoreboard.StartPeriod(); }
-            } while (scoreboard.Offense is not null);
+            }
         }
     }
 
@@ -67,62 +67,23 @@ internal class Game
         if (shot == 0)
         {
             defense.Set(_io.ReadDefense("Your new defensive alignment is"));
+            _io.WriteLine();
             return false;
         }
 
-        var playContinues = false;
+        var playContinues = shot >= 3;
 
         if (shot == 1 || shot == 2)
         {
             clock.Increment(scoreboard);
             if (clock.IsHalfTime) { return false; }
 
-            _io.WriteLine("Jump shot");
+            Resolve("Jump shot", defense / 8)
-            if (_random.NextFloat() <= 0.341f * defense / 8)
+                .Do(0.341f, () => scoreboard.AddBasket("Shot is good"))
-            {
+                .Or(0.682f, () => ResolveShotOffTarget())
-                scoreboard.AddBasket("Shot is good");
+                .Or(0.782f, () => ContestBall(0.5f, scoreboard, "Shot is blocked.  Ball controlled by {0}."))
-            }
+                .Or(0.843f, () => ResolveFreeThrows(scoreboard, "Shooter is fouled.  Two shots."))
-            else if (_random.NextFloat() <= 0.682f * defense / 8)
+                .Or(() => scoreboard.Turnover("Charging foul.  Dartmouth loses ball."));
-            {
-                _io.WriteLine("Shot is off target");
-                if (defense / 6 * _random.NextFloat() > 0.45f)
-                {
-                    scoreboard.Turnover($"Rebound to {scoreboard.Visitors}");
-                }
-                else
-                {
-                    _io.WriteLine("Dartmouth controls the rebound.");
-                    if (_random.NextFloat() <= 0.4f)
-                    {
-                        playContinues = true;
-                    }
-                    else
-                    {
-                        if (defense == 6)
-                        {
-                            if (_random.NextFloat() > 0.6f)
-                            {
-                                scoreboard.Turnover();
-                                scoreboard.AddBasket($"Pass stolen by {scoreboard.Visitors} easy layup.");
-                                _io.WriteLine();
-                            }
-                        }
-                        _io.Write("Ball passed back to you. ");
-                    }
-                }
-            }
-            else if (_random.NextFloat() <= 0.782f * defense / 8)
-            {
-                scoreboard.Offense = ContestBall(0.5f, scoreboard, "Shot is blocked.  Ball controlled by {0}.");
-            }
-            else if (_random.NextFloat() <= 0.843f * defense / 8)
-            {
-                FreeThrows(scoreboard, "Shooter is fouled.  Two shots.");
-            }
-            else
-            {
-                scoreboard.Turnover("Charging foul.  Dartmouth loses ball.");
-            }
         }
 
         while (playContinues)
@@ -132,47 +93,38 @@ internal class Game
 
             playContinues = false;
 
-            _io.WriteLine(shot == 3 ? "Lay up." : "Set shot.");
+            Resolve(shot == 3 ? "Lay up." : "Set shot.", defense / 7)
-
+                .Do(0.4f, () => scoreboard.AddBasket("Shot is good.  Two points."))
-            if (_random.NextFloat() <= 0.4f * defense / 7)
+                .Or(0.7f, () => ResolveShotOffTheRim())
-            {
+                .Or(0.875f, () => ResolveFreeThrows(scoreboard, "Shooter fouled.  Two shots."))
-                scoreboard.AddBasket("Shot is good.  Two points.");
+                .Or(0.925f, () => scoreboard.Turnover($"Shot blocked. {scoreboard.Visitors}'s ball."))
-            }
+                .Or(() => scoreboard.Turnover("Charging foul.  Dartmouth loses ball."));
-            else if (_random.NextFloat() <= 0.7f * defense / 7)
-            {
-                _io.WriteLine("Shot is off the rim.");
-                if (_random.NextFloat() <= 2 / 3f)
-                {
-                    scoreboard.Turnover($"{scoreboard.Visitors} controls the rebound.");
-                }
-                else
-                {
-                    _io.WriteLine("Dartmouth controls the rebound");
-                    if (_random.NextFloat() <= 0.4f)
-                    {
-                        playContinues = true;
-                    }
-                    else
-                    {
-                        _io.WriteLine("Ball passed back to you.");
-                    }
-                }
-            }
-            else if (_random.NextFloat() <= 0.875f * defense / 7)
-            {
-                FreeThrows(scoreboard, "Shooter fouled.  Two shots.");
-            }
-            else if (_random.NextFloat() <= 0.925f * defense / 7)
-            {
-                scoreboard.Turnover($"Shot blocked. {scoreboard.Visitors}'s ball.");
-            }
-            else
-            {
-                scoreboard.Turnover("Charging foul.  Dartmouth loses ball.");
-            }
         }
 
         return false;
+
+        void ResolveShotOffTarget() =>
+            Resolve("Shot is off target", 6 / defense)
+                .Do(0.45f, () => Resolve("Dartmouth controls the rebound.")
+                    .Do(0.4f, () => playContinues = true)
+                    .Or(() =>
+                    {
+                        if (defense == 6 && _random.NextFloat() > 0.6f)
+                        {
+                            scoreboard.Turnover();
+                            scoreboard.AddBasket($"Pass stolen by {scoreboard.Visitors} easy layup.");
+                            _io.WriteLine();
+                        }
+                        _io.Write("Ball passed back to you. ");
+                    }))
+                .Or(() => scoreboard.Turnover($"Rebound to {scoreboard.Visitors}"));
+
+        void ResolveShotOffTheRim() =>
+            Resolve("Shot is off the rim.")
+                .Do(2 / 3f, () => scoreboard.Turnover($"{scoreboard.Visitors} controls the rebound."))
+                .Or(() => Resolve("Dartmouth controls the rebound")
+                    .Do(0.4f, () => playContinues = true)
+                    .Or(() => _io.WriteLine("Ball passed back to you.")));
     };
 
     private Func<Scoreboard, bool> VisitingTeamPlay(Clock clock, Defense defense) => scoreboard =>
@@ -180,123 +132,79 @@ internal class Game
         clock.Increment(scoreboard);
         if (clock.IsHalfTime) { return false; }
 
-        var playContinues = false;
 
         _io.WriteLine();
         var shot = _random.NextFloat(1, 3.5f);
+        var playContinues = shot > 2;
+
         if (shot <= 2)
         {
-            _io.WriteLine("Jump shot.");
+            Resolve("Jump shot.", defense / 8)
+                .Do(0.35f, () => scoreboard.AddBasket("Shot is good."))
+                .Or(0.75f, () => ResolveBadShot("Shot is off the rim.", defense * 6))
+                .Or(0.9f, () => ResolveFreeThrows(scoreboard, "Player fouled.  Two shots."))
+                .Or(() => _io.WriteLine("Offensive foul.  Dartmouth's ball."));
 
-            if (_random.NextFloat() <= 0.35f * defense / 8)
+            _io.WriteLine();
-            {
-                scoreboard.AddBasket("Shot is good.");
-            }
-            else if (_random.NextFloat() <= 0.75f * defense / 8)
-            {
-                _io.WriteLine("Shot is off the rim.");
-                if (_random.NextFloat() <= 0.5f / defense * 6)
-                {
-                    scoreboard.Turnover("Dartmouth controls the rebound.");
-                }
-                else
-                {
-                    _io.WriteLine($"{scoreboard.Visitors} controls the rebound.");
-                    if (defense == 6)
-                    {
-                        if (_random.NextFloat() <= 0.25f)
-                        {
-                            scoreboard.Turnover();
-                            scoreboard.AddBasket("Ball stolen.  Easy lay up for Dartmouth.");
-                            _io.WriteLine();
-                            return false;
-                        }
-                    }
-                    if (_random.NextFloat() <= 0.5f)
-                    {
-                        _io.WriteLine($"Pass back to {scoreboard.Visitors} guard.");
-                        return false;
-                    }
-
-                    playContinues = true;
-                }
-            }
-            else if (_random.NextFloat() <= 0.9f * defense / 8)
-            {
-                FreeThrows(scoreboard, "Player fouled.  Two shots.");
-            }
-            else
-            {
-                _io.WriteLine("Offensive foul.  Dartmouth's ball.");
-            }
         }
 
         while (playContinues)
         {
             playContinues = false;
 
-            _io.WriteLine(shot > 3 ? "Set shot." : "Lay up.");
+            Resolve(shot > 3 ? "Set shot." : "Lay up.", defense / 7)
-
+                .Do(0.413f, () => scoreboard.AddBasket("Shot is good."))
-            if (_random.NextFloat() <= 0.413f * defense / 7)
+                .Or(() => ResolveBadShot("Shot is missed.", 6 / defense));
-            {
+            _io.WriteLine();
-                scoreboard.AddBasket("Shot is good.");
-            }
-            else
-            {
-                _io.WriteLine("Shot is missed.");
-                if (_random.NextFloat() <= 0.5f * 6 / defense)
-                {
-                    scoreboard.Turnover("Dartmouth controls the rebound.");
-                }
-                else
-                {
-                    _io.WriteLine($"{scoreboard.Visitors} controls the rebound.");
-                    if (defense == 6)
-                    {
-                        if (_random.NextFloat() <= 0.25f)
-                        {
-                            scoreboard.Turnover();
-                            scoreboard.AddBasket("Ball stolen.  Easy lay up for Dartmouth.");
-                            _io.WriteLine();
-                            return false;
-                        }
-                    }
-                    if (_random.NextFloat() <= 0.5f)
-                    {
-                        _io.WriteLine($"Pass back to {scoreboard.Visitors} guard.");
-                        return false;
-                    }
-
-                    playContinues = true;
-                }
-            }
         }
 
         return false;
+
+        void ResolveBadShot(string message, float defenseFactor) =>
+            Resolve("Shot is off the rim.", defense * 6)
+                .Do(0.5f, () => scoreboard.Turnover("Dartmouth controls the rebound."))
+                .Or(() => ResolveVisitorsRebound());
+
+        void ResolveVisitorsRebound()
+        {
+            _io.Write($"{scoreboard.Visitors} controls the rebound.");
+            if (defense == 6 && _random.NextFloat() <= 0.25f)
+            {
+                _io.WriteLine();
+                scoreboard.Turnover();
+                scoreboard.AddBasket("Ball stolen.  Easy lay up for Dartmouth.");
+                return;
+            }
+
+            if (_random.NextFloat() <= 0.5f)
+            {
+                _io.WriteLine();
+                _io.Write($"Pass back to {scoreboard.Visitors} guard.");
+                return;
+            }
+
+            playContinues = true;
+        }
     };
 
-    Team ContestBall(float probability, Scoreboard scoreboard, string messageFormat)
+    void ContestBall(float probability, Scoreboard scoreboard, string messageFormat)
     {
         var winner = _random.NextFloat() <= probability ? scoreboard.Home : scoreboard.Visitors;
+        scoreboard.Offense = winner;
         _io.WriteLine(messageFormat, winner);
-        return winner;
     }
 
-    void FreeThrows(Scoreboard scoreboard, string message)
+    void ResolveFreeThrows(Scoreboard scoreboard, string message) =>
+        Resolve(message)
+            .Do(0.49f, () => scoreboard.AddFreeThrows(2, "Shooter makes both shots."))
+            .Or(0.75f, () => scoreboard.AddFreeThrows(1, "Shooter makes one shot and misses one."))
+            .Or(() => scoreboard.AddFreeThrows(0, "Both shots missed."));
+
+    private Probably Resolve(string message) => Resolve(message, 1f);
+
+    private Probably Resolve(string message, float defenseFactor)
     {
         _io.WriteLine(message);
-
+        return new Probably(defenseFactor, _random);
-        if (_random.NextFloat() <= 0.49)
-        {
-            scoreboard.AddFreeThrows(2, "Shooter makes both shots.");
-        }
-        else if (_random.NextFloat() <= 0.75)
-        {
-            scoreboard.AddFreeThrows(1, "Shooter makes one shot and misses one.");
-        }
-        else
-        {
-            scoreboard.AddFreeThrows(0, "Both shots missed.");
-        }
     }
 }

07_Basketball/csharp/Probably.cs

@@ -0,0 +1,32 @@
+using Games.Common.Randomness;
+
+namespace Basketball;
+
+internal struct Probably
+{
+    private readonly float _defenseFactor;
+    private readonly IRandom _random;
+    private readonly bool _done;
+
+    internal Probably(float defenseFactor, IRandom random, bool done = false)
+    {
+        _defenseFactor = defenseFactor;
+        _random = random;
+        _done = done;
+    }
+
+    public Probably Do(float probability, Action action)
+    {
+        if (!_done && _random.NextFloat() <= probability * _defenseFactor)
+        {
+            action.Invoke();
+            return new Probably(_defenseFactor, _random, true);
+        }
+
+        return this;
+    }
+
+    public Probably Or(float probability, Action action) => Do(probability, action);
+
+    public Probably Or(Action action) => Do(1f, action);
+}