Fix fake players not being able to respawn for exiting the end (#1664)

* Allow fake players to respawn (to return from the end)
* Fixes #1645 (Fake players get stuck in the end exit portal)

* fix up some imports

src/main/java/carpet/mixins/PlayerList_fakePlayersMixin.java

@@ -1,8 +1,10 @@
 package carpet.mixins;
 
+import com.mojang.authlib.GameProfile;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.network.Connection;
 import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.server.network.ServerGamePacketListenerImpl;
 import net.minecraft.server.players.PlayerList;
@@ -44,4 +46,13 @@ public abstract class PlayerList_fakePlayersMixin
             return new ServerGamePacketListenerImpl(this.server, clientConnection, playerIn);
         }
     }
-}
+
+    @Redirect(method = "respawn", at = @At(value = "NEW", target = "net/minecraft/server/level/ServerPlayer"))
+    public ServerPlayer makePlayerForRespawn(MinecraftServer minecraftServer, ServerLevel serverLevel, GameProfile gameProfile, ServerPlayer serverPlayer, boolean bl)
+    {
+        if (serverPlayer instanceof EntityPlayerMPFake) {
+            return EntityPlayerMPFake.respawnFake(minecraftServer, serverLevel, gameProfile);
+        }
+        return new ServerPlayer(minecraftServer, serverLevel, gameProfile);
+    }
+}

src/main/java/carpet/patches/EntityPlayerMPFake.java

@@ -9,6 +9,7 @@ import net.minecraft.network.protocol.PacketFlow;
 import net.minecraft.network.protocol.game.ClientboundPlayerInfoUpdatePacket;
 import net.minecraft.network.protocol.game.ClientboundRotateHeadPacket;
 import net.minecraft.network.protocol.game.ClientboundTeleportEntityPacket;
+import net.minecraft.network.protocol.game.ServerboundClientCommandPacket;
 import net.minecraft.resources.ResourceKey;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.TickTask;
@@ -104,6 +105,11 @@ public class EntityPlayerMPFake extends ServerPlayer
         return playerShadow;
     }
 
+    public static EntityPlayerMPFake respawnFake(MinecraftServer server, ServerLevel level, GameProfile profile)
+    {
+        return new EntityPlayerMPFake(server, level, profile, false);
+    }
+
     private EntityPlayerMPFake(MinecraftServer server, ServerLevel worldIn, GameProfile profile, boolean shadow)
     {
         super(server, worldIn, profile);
@@ -137,7 +143,6 @@ public class EntityPlayerMPFake extends ServerPlayer
         {
             this.connection.resetPosition();
             this.getLevel().getChunkSource().move(this);
-            hasChangedDimension(); //<- causes hard crash but would need to be done to enable portals // not as of 1.17
         }
         try
         {
@@ -182,4 +187,21 @@ public class EntityPlayerMPFake extends ServerPlayer
     protected void checkFallDamage(double y, boolean onGround, BlockState state, BlockPos pos) {
         doCheckFallDamage(y, onGround);
     }
+
+    @Override
+    public Entity changeDimension(ServerLevel serverLevel)
+    {
+        super.changeDimension(serverLevel);
+        if (wonGame) {
+            ServerboundClientCommandPacket p = new ServerboundClientCommandPacket(ServerboundClientCommandPacket.Action.PERFORM_RESPAWN);
+            connection.handleClientCommand(p);
+        }
+
+        // If above branch was taken, *this* has been removed and replaced, the new instance has been set
+        // on 'our' connection (which is now theirs, but we still have a ref).
+        if (connection.player.isChangingDimension()) {
+            connection.player.hasChangedDimension();
+        }
+        return connection.player;
+    }
 }