[Bleeding] Implement methods for /achievement command. Addresses BUKKIT-4932

src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java

@@ -1,5 +1,7 @@
 package org.bukkit.craftbukkit.util;
 
+import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.List;
 
 import net.minecraft.server.Block;
@@ -7,9 +9,13 @@ import net.minecraft.server.Blocks;
 import net.minecraft.server.Item;
 import net.minecraft.server.MojangsonParser;
 import net.minecraft.server.NBTTagCompound;
+import net.minecraft.server.StatisticList;
 
+import org.bukkit.Achievement;
 import org.bukkit.Material;
+import org.bukkit.Statistic;
 import org.bukkit.UnsafeValues;
+import org.bukkit.craftbukkit.CraftStatistic;
 import org.bukkit.craftbukkit.inventory.CraftItemStack;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.util.StringUtil;
@@ -100,4 +106,27 @@ public final class CraftMagicNumbers implements UnsafeValues {
 
         return stack;
     }
+
+    @Override
+    public Statistic getStatisticFromInternalName(String name) {
+        return CraftStatistic.getBukkitStatisticByName(name);
+    }
+
+    @Override
+    public Achievement getAchievementFromInternalName(String name) {
+        return CraftStatistic.getBukkitAchievementByName(name);
+    }
+
+    @Override
+    public List<String> tabCompleteInternalStatisticOrAchievementName(String token, List<String> completions) {
+        List<String> matches = new ArrayList<String>();
+        Iterator iterator = StatisticList.b.iterator();
+        while (iterator.hasNext()) {
+            String statistic = ((net.minecraft.server.Statistic) iterator.next()).e;
+            if (statistic.startsWith(token)) {
+                matches.add(statistic);
+            }
+        }
+        return matches;
+    }
 }