From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sat, 15 May 2021 10:04:43 -0700
Subject: [PATCH] additions to PlayerGameModeChangeEvent


diff --git a/src/main/java/net/minecraft/server/commands/DefaultGameModeCommands.java b/src/main/java/net/minecraft/server/commands/DefaultGameModeCommands.java
index d25a27f3a6775ca86092ea8bdeab4abdd8909d35..7d9ec435f3821f95d3bed893c4e46d5a2531cd58 100644
--- a/src/main/java/net/minecraft/server/commands/DefaultGameModeCommands.java
+++ b/src/main/java/net/minecraft/server/commands/DefaultGameModeCommands.java
@@ -31,9 +31,13 @@ public class DefaultGameModeCommands {
         GameType gameType = minecraftServer.getForcedGameType();
         if (gameType != null) {
             for(ServerPlayer serverPlayer : minecraftServer.getPlayerList().getPlayers()) {
-                if (serverPlayer.setGameMode(gameType)) {
-                    ++i;
+                // Paper start - extend PlayerGameModeChangeEvent
+                org.bukkit.event.player.PlayerGameModeChangeEvent event = serverPlayer.setGameMode(gameType, org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.DEFAULT_GAMEMODE, net.kyori.adventure.text.Component.empty());
+                if (event != null && event.isCancelled()) {
+                    source.sendSuccess(io.papermc.paper.adventure.PaperAdventure.asVanilla(event.cancelMessage()), false);
                 }
+                // Paper end
+                    ++i;
             }
         }
 
diff --git a/src/main/java/net/minecraft/server/commands/GameModeCommand.java b/src/main/java/net/minecraft/server/commands/GameModeCommand.java
index d75f78d2e3fb1376e8f6a8668c98a04a693c99e1..79f6089b934124c3309c6bee2e48b36b937252e0 100644
--- a/src/main/java/net/minecraft/server/commands/GameModeCommand.java
+++ b/src/main/java/net/minecraft/server/commands/GameModeCommand.java
@@ -52,9 +52,14 @@ public class GameModeCommand {
         int i = 0;
 
         for(ServerPlayer serverPlayer : targets) {
-            if (serverPlayer.setGameMode(gameMode)) {
+            // Paper start - extend PlayerGameModeChangeEvent
+            org.bukkit.event.player.PlayerGameModeChangeEvent event = serverPlayer.setGameMode(gameMode, org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.COMMAND, net.kyori.adventure.text.Component.empty());
+            if (event != null && !event.isCancelled()) {
                 logGamemodeChange(context.getSource(), serverPlayer, gameMode);
                 ++i;
+            } else if (event != null && event.cancelMessage() != null) {
+                context.getSource().sendSuccess(io.papermc.paper.adventure.PaperAdventure.asVanilla(event.cancelMessage()), true);
+                // Paper end
             }
         }
 
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index a5bf54d6ad99d2cd860e9a8dc87a5dcfac5c18ac..53f6a45a505725c81ab15bd2daa1c61b024f1d68 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -1783,8 +1783,15 @@ public class ServerPlayer extends Player {
     }
 
     public boolean setGameMode(GameType gameMode) {
-        if (!this.gameMode.changeGameModeForPlayer(gameMode)) {
-            return false;
+        // Paper start - Add cause and nullable message to event
+        PlayerGameModeChangeEvent event = this.setGameMode(gameMode, org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.UNKNOWN, null);
+        return event == null ? false : event.isCancelled();
+    }
+    public PlayerGameModeChangeEvent setGameMode(GameType gameMode, PlayerGameModeChangeEvent.Cause cause, net.kyori.adventure.text.Component message) {
+        PlayerGameModeChangeEvent event = this.gameMode.changeGameModeForPlayer(gameMode, cause, message);
+        if (event == null || event.isCancelled()) {
+            // Paper end
+            return null;
         } else {
             this.connection.send(new ClientboundGameEventPacket(ClientboundGameEventPacket.CHANGE_GAME_MODE, (float) gameMode.getId()));
             if (gameMode == GameType.SPECTATOR) {
@@ -1796,7 +1803,7 @@ public class ServerPlayer extends Player {
 
             this.onUpdateAbilities();
             this.updateEffectVisibility();
-            return true;
+            return event; // Paper
         }
     }
 
@@ -2178,6 +2185,14 @@ public class ServerPlayer extends Player {
     }
 
     public void loadGameTypes(@Nullable CompoundTag nbt) {
+        if (this.server.getForcedGameType() != null && this.server.getForcedGameType() != ServerPlayer.readPlayerMode(nbt, "playerGameType")) {
+            if (new PlayerGameModeChangeEvent(this.getBukkitEntity(), GameMode.getByValue(this.server.getDefaultGameType().getId()), org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.DEFAULT_GAMEMODE, null).callEvent()) {
+                this.gameMode.setGameModeForPlayer(this.server.getForcedGameType(), GameType.DEFAULT_MODE);
+            } else {
+                this.gameMode.setGameModeForPlayer(ServerPlayer.readPlayerMode(nbt,"playerGameType"), ServerPlayer.readPlayerMode(nbt, "previousPlayerGameType"));
+            }
+            return;
+        }
         this.gameMode.setGameModeForPlayer(this.calculateGameModeForNewPlayer(ServerPlayer.readPlayerMode(nbt, "playerGameType")), ServerPlayer.readPlayerMode(nbt, "previousPlayerGameType"));
     }
 
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayerGameMode.java b/src/main/java/net/minecraft/server/level/ServerPlayerGameMode.java
index b096384cdc7596166e010e06272534b8001693c9..4b756c0a4b607faa03b00ab81761335be63c39eb 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayerGameMode.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayerGameMode.java
@@ -74,18 +74,24 @@ public class ServerPlayerGameMode {
     }
 
     public boolean changeGameModeForPlayer(GameType gameMode) {
+        // Paper end
+        PlayerGameModeChangeEvent event = this.changeGameModeForPlayer(gameMode, org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.UNKNOWN, null);
+        return event == null ? false : event.isCancelled();
+    }
+    public PlayerGameModeChangeEvent changeGameModeForPlayer(GameType gameMode, org.bukkit.event.player.PlayerGameModeChangeEvent.Cause cause, net.kyori.adventure.text.Component component) {
+        // Paper end
         if (gameMode == this.gameModeForPlayer) {
-            return false;
+            return null; // Paper
         } else {
             // CraftBukkit start
             PlayerGameModeChangeEvent event = new PlayerGameModeChangeEvent(this.player.getBukkitEntity(), GameMode.getByValue(gameMode.getId()));
             this.level.getCraftServer().getPluginManager().callEvent(event);
             if (event.isCancelled()) {
-                return false;
+                return event; // Paper
             }
             // CraftBukkit end
             this.setGameModeForPlayer(gameMode, this.gameModeForPlayer);
-            return true;
+            return event; // Paper
         }
     }
 
diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index 0b2cb820b912ddb6366f7ffb79c71047d03f2001..52294f5cfce86faf301c835bf1a9c2a5f4f5d721 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -2470,7 +2470,7 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Ser
 
                     this.player = this.server.getPlayerList().respawn(this.player, false);
                     if (this.server.isHardcore()) {
-                        this.player.setGameMode(GameType.SPECTATOR);
+                        this.player.setGameMode(GameType.SPECTATOR, org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.HARDCORE_DEATH, null); // Paper
                         ((GameRules.BooleanValue) this.player.getLevel().getGameRules().getRule(GameRules.RULE_SPECTATORSGENERATECHUNKS)).set(false, this.server);
                     }
                 }
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index 2314b1ab177fdc5dcbf96a998d9b1d0a86e10037..23bbb36a8035fe29046d51cf18b958d5cad7ea68 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -1246,7 +1246,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
             throw new IllegalArgumentException("Mode cannot be null");
         }
 
-        this.getHandle().setGameMode(GameType.byId(mode.getValue()));
+        this.getHandle().setGameMode(GameType.byId(mode.getValue()), org.bukkit.event.player.PlayerGameModeChangeEvent.Cause.PLUGIN, null); // Paper
     }
 
     @Override