Implements switching Pokemon and fleeing from battle

Plugins/PkmnLib.Plugin.Gen7/Libraries/Gen7MiscLibrary.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Linq;
 using PkmnLib.Dynamic;
 using PkmnLib.Dynamic.Libraries;
 using PkmnLib.Dynamic.Models;
@@ -35,4 +36,31 @@ public class Gen7MiscLibrary : IMiscLibrary
             _ => TimeOfDay.Night,
         };
     }
+
+    /// <inheritdoc />
+    public bool CanFlee(IBattle battle, IFleeChoice fleeChoice)
+    {
+        var user = fleeChoice.User;
+        var battleData = user.BattleData;
+        if (battleData == null)
+            return false;
+        var opponentSide = battle.Sides[battleData.SideIndex == 0 ? 1 : 0];
+        var opponent = opponentSide.Pokemon.FirstOrDefault(x => x is not null);
+        if (opponent == null)
+            return true;
+        
+        var userSpeed = user.FlatStats.Speed;
+        var opponentSpeed = opponent.FlatStats.Speed;
+        // If the player's active Pokémon's Speed is greater than or equal to the wild Pokémon's Speed, fleeing will
+        // always succeed
+        if (userSpeed >= opponentSpeed)
+            return true;
+        
+        var userSide = battle.Sides[battleData.SideIndex];
+        
+        userSide.RegisterFleeAttempt();
+        var fleeChance = ((userSpeed * 32) / (opponentSpeed / 4) + (30 * userSide.FleeAttempts)) / 256;
+        var random = battle.Random.GetInt(0, 100);
+        return random < fleeChance;
+    }
 }