bukkit: add GameMode.SPECTATOR for mods that provide the game type

patches/org/bukkit/GameMode.java.patch

@@ -14,3 +14,22 @@
       * Creative mode may fly, build instantly, become invulnerable and create
       * free items.
       */
+@@ -25,8 +31,17 @@
+     /**
+      * Adventure mode cannot break blocks, use chat, use buckets, etc.
+      */
+-    ADVENTURE(2);
++    ADVENTURE(2),
+
++    // Crucible start - plugins built against 1.8+ APIs reference SPECTATOR directly
++    /**
++     * Spectator mode cannot interact with the world and is invisible to
++     * other players. Only available when a mod adds the spectator game type;
++     * otherwise the server refuses to switch to it.
++     */
++    SPECTATOR(3);
++    // Crucible end
++
+     private final int value;
+     private final static Map<Integer, GameMode> BY_ID = Maps.newHashMap();
+

patches/org/bukkit/command/defaults/GameModeCommand.java.patch

@@ -1,6 +1,22 @@
 --- ../src-base/minecraft/org/bukkit/command/defaults/GameModeCommand.java
 +++ ../src-work/minecraft/org/bukkit/command/defaults/GameModeCommand.java
-@@ -50,7 +50,7 @@
+@@ -9,13 +9,14 @@
+ import org.bukkit.GameMode;
+ import org.bukkit.command.Command;
+ import org.bukkit.command.CommandSender;
++import org.bukkit.craftbukkit.v1_7_R4.entity.CraftPlayer; // Crucible
+ import org.bukkit.entity.Player;
+ import org.bukkit.util.StringUtil;
+
+ import com.google.common.collect.ImmutableList;
+
+ public class GameModeCommand extends VanillaCommand {
+-    private static final List<String> GAMEMODE_NAMES = ImmutableList.of("adventure", "creative", "survival");
++    private static final List<String> GAMEMODE_NAMES = ImmutableList.of("adventure", "creative", "survival", "spectator"); // Crucible
+
+     public GameModeCommand() {
+         super("gamemode");
+@@ -50,16 +51,28 @@
 
              GameMode mode = GameMode.getByValue(value);
 
@@ -9,3 +25,24 @@
                  if (modeArg.equalsIgnoreCase("creative") || modeArg.equalsIgnoreCase("c")) {
                      mode = GameMode.CREATIVE;
                  } else if (modeArg.equalsIgnoreCase("adventure") || modeArg.equalsIgnoreCase("a")) {
+                     mode = GameMode.ADVENTURE;
++                // Crucible start
++                } else if (modeArg.equalsIgnoreCase("spectator") || modeArg.equalsIgnoreCase("sp")) {
++                    mode = GameMode.SPECTATOR;
++                // Crucible end
+                 } else {
+                     mode = GameMode.SURVIVAL;
+                 }
+             }
+
++            // Crucible start
++            if (!CraftPlayer.isGameModeAvailable(mode)) {
++                sender.sendMessage(ChatColor.RED + "Game mode " + mode + " is not available on this server: no installed mod adds it. "
++                        + "Install a mod that does (suggestion: Et Futurum Requiem) to use it.");
++                return true;
++            }
++            // Crucible end
++
+             if (mode != player.getGameMode()) {
+                 player.setGameMode(mode);
+

src/main/java/org/bukkit/craftbukkit/v1_7_R4/entity/CraftPlayer.java

@@ -11,6 +11,7 @@
 import net.minecraft.item.Item;
 import net.minecraft.network.play.server.*;
 import net.minecraft.world.WorldServer;
+import net.minecraft.world.WorldSettings;
 import org.apache.commons.lang.NotImplementedException;
 import org.apache.commons.lang.Validate;
 import org.bukkit.*;
@@ -859,6 +860,15 @@ public GameMode getGameMode() {
         return GameMode.getByValue(getHandle().theItemInWorldManager.getGameType().getID());
     }
 
+    /**
+     * Whether the server has a game type for {@code mode}. SPECTATOR exists in the API for newer plugins,
+     * but only becomes available when a mod registers the spectator game type.
+     */
+    public static boolean isGameModeAvailable(GameMode mode) {
+        // GameType.getByID falls back to SURVIVAL for an id no one registered
+        return WorldSettings.GameType.getByID(mode.getValue()).getID() == mode.getValue();
+    }
+
     @Override
     public void setGameMode(GameMode mode) {
         if (getHandle().playerNetServerHandler == null) return;
@@ -867,6 +877,12 @@ public void setGameMode(GameMode mode) {
             throw new IllegalArgumentException("Mode cannot be null");
         }
 
+        if (!isGameModeAvailable(mode)) {
+            server.getLogger().warning("Game mode of " + getName() + " left unchanged at " + getGameMode() + ": " + mode
+                    + " is not available because no installed mod adds that game type. Install one that does, or pick another mode.");
+            return;
+        }
+
         if (mode != getGameMode()) {
             PlayerGameModeChangeEvent event = new PlayerGameModeChangeEvent(this, mode);
             server.getPluginManager().callEvent(event);