Simplify Combat (C#) folder structure

28_Combat/csharp/Ceasefire.cs

@@ -0,0 +1,60 @@
+using System;
+
+namespace Game
+{
+    /// <summary>
+    /// Represents the state of the game after reaching a ceasefire.
+    /// </summary>
+    public sealed class Ceasefire : WarState
+    {
+        /// <summary>
+        /// Gets a flag indicating whether the player achieved absolute victory.
+        /// </summary>
+        public override bool IsAbsoluteVictory { get; }
+
+        /// <summary>
+        /// Gets the outcome of the war.
+        /// </summary>
+        public override WarResult? FinalOutcome
+        {
+            get
+            {
+                if (IsAbsoluteVictory || PlayerForces.TotalTroops > 3 / 2 * ComputerForces.TotalTroops)
+                    return WarResult.PlayerVictory;
+                else
+                if (PlayerForces.TotalTroops < 2 / 3 * ComputerForces.TotalTroops)
+                    return WarResult.ComputerVictory;
+                else
+                    return WarResult.PeaceTreaty;
+            }
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the Ceasefire class.
+        /// </summary>
+        /// <param name="computerForces">
+        /// The computer's forces.
+        /// </param>
+        /// <param name="playerForces">
+        /// The player's forces.
+        /// </param>
+        /// <param name="absoluteVictory">
+        /// Indicates whether the player acheived absolute victory (defeating
+        /// the computer without destroying its military).
+        /// </param>
+        public Ceasefire(ArmedForces computerForces, ArmedForces playerForces, bool absoluteVictory = false)
+            : base(computerForces, playerForces)
+        {
+            IsAbsoluteVictory = absoluteVictory;
+        }
+
+        protected override (WarState nextState, string message) AttackWithArmy(int attackSize) =>
+            throw new InvalidOperationException("THE WAR IS OVER");
+
+        protected override (WarState nextState, string message) AttackWithNavy(int attackSize) =>
+            throw new InvalidOperationException("THE WAR IS OVER");
+
+        protected override (WarState nextState, string message) AttackWithAirForce(int attackSize) =>
+            throw new InvalidOperationException("THE WAR IS OVER");
+    }
+}