Expand GameRule API

src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -22,6 +22,7 @@ import org.bukkit.Chunk;
 import org.bukkit.ChunkSnapshot;
 import org.bukkit.Difficulty;
 import org.bukkit.Effect;
+import org.bukkit.GameRule;
 import org.bukkit.Location;
 import org.bukkit.Particle;
 import org.bukkit.Sound;
@@ -41,7 +42,6 @@ import org.bukkit.craftbukkit.inventory.CraftItemStack;
 import org.bukkit.craftbukkit.metadata.BlockMetadataStore;
 import org.bukkit.craftbukkit.potion.CraftPotionUtil;
 import org.bukkit.craftbukkit.util.CraftMagicNumbers;
-import org.bukkit.craftbukkit.util.LongHash;
 import org.bukkit.entity.*;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.minecart.CommandMinecart;
@@ -1465,9 +1465,48 @@ public class CraftWorld implements World {
     }
 
     public boolean isGameRule(String rule) {
+        Validate.isTrue(rule != null && !rule.isEmpty(), "Rule cannot be null nor empty");
         return GameRules.getGameRules().containsKey(rule);
     }
 
+    @Override
+    public <T> T getGameRuleValue(GameRule<T> rule) {
+        Validate.notNull(rule, "GameRule cannot be null");
+        return convert(rule, getHandle().getGameRules().get(rule.getName()));
+    }
+
+    @Override
+    public <T> T getGameRuleDefault(GameRule<T> rule) {
+        Validate.notNull(rule, "GameRule cannot be null");
+        return convert(rule, GameRules.getGameRules().get(rule.getName()).a());
+    }
+
+    @Override
+    public <T> boolean setGameRule(GameRule<T> rule, T newValue) {
+        Validate.notNull(rule, "GameRule cannot be null");
+        Validate.notNull(newValue, "GameRule value cannot be null");
+
+        if (!isGameRule(rule.getName())) return false;
+
+        getHandle().getGameRules().set(rule.getName(), newValue.toString(), getHandle().getMinecraftServer());
+        return true;
+    }
+
+    private <T> T convert(GameRule<T> rule, GameRules.GameRuleValue value) {
+        if (value == null) {
+            return null;
+        }
+
+        switch (value.e()) {
+            case BOOLEAN_VALUE:
+                return rule.getType().cast(value.b());
+            case NUMERICAL_VALUE:
+                return rule.getType().cast(value.c());
+            default:
+                throw new IllegalArgumentException("Invalid GameRule type (" + value.e() + ") for GameRule " + rule.getName());
+        }
+    }
+
     @Override
     public WorldBorder getWorldBorder() {
         if (this.worldBorder == null) {

src/test/java/org/bukkit/GameRuleTest.java

@@ -0,0 +1,56 @@
+package org.bukkit;
+
+import java.util.Map;
+import java.util.TreeMap;
+import net.minecraft.server.GameRules;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class GameRuleTest {
+
+    @Test
+    public void testBukkitRules() {
+        GameRule<?>[] rules = GameRule.values();
+
+        for (GameRule<?> rule : rules) {
+            GameRule<?> registeredRule = GameRule.getByName(rule.getName());
+            Assert.assertNotNull("Null GameRule", registeredRule);
+            Assert.assertEquals("Invalid GameRule equality", rule, registeredRule);
+        }
+    }
+
+    @Test
+    public void testMinecraftRules() {
+        TreeMap<String, GameRules.b> minecraftRules = GameRules.getGameRules();
+
+        for (Map.Entry<String, GameRules.b> entry : minecraftRules.entrySet()) {
+            GameRule<?> bukkitRule = GameRule.getByName(entry.getKey());
+
+            Assert.assertNotNull(bukkitRule);
+            Assert.assertEquals("Invalid GameRule Name", bukkitRule.getName(), entry.getKey());
+        }
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void nullGameRuleName() {
+        GameRule.getByName(null);
+    }
+
+    @Test
+    public void emptyGameRuleName() {
+        Assert.assertNull(GameRule.getByName(""));
+    }
+
+    @Test
+    public void incorrectGameRuleName() {
+        Assert.assertNull(GameRule.getByName("doAnnounceAdvancements"));
+        Assert.assertNull(GameRule.getByName("sendCommandBlockFeedback"));
+    }
+
+    @Test
+    public void invalidCasing() {
+        Assert.assertNull(GameRule.getByName("CommandBlockOutput"));
+        Assert.assertNull(GameRule.getByName("spAwnRadius"));
+        Assert.assertNull(GameRule.getByName("rand0mTickSpeEd"));
+    }
+}