Add support for extended and/or upgraded potions in the item syntax.

This commit adds support for altering the data portion of a potion item by prefixing either `long_` or `strong_` to get extended duration or level II versions of the given potion, respectively.

Closes #520

changelog.md

@@ -11,6 +11,7 @@ These changes will (most likely) be included in the next version.
 
 
 ## [Unreleased]
+- Extended and upgraded potions are now supported in the item syntax by prepending `long_` or `strong_` to the data portion of a potion item (e.g. `potion:strong_instant_heal:1` will yield a Potion of Healing II). Check the wiki for details.
 - Tridents and crossbows are now considered weapons with regards to the `unbreakable-weapons` flag. All class items that have durability now have their unbreakable flag set to true unless the `unbreakable-weapons` and/or `unbreakable-armor` flags are set to `false`.
 - Leaderboards now work again on servers running Minecraft 1.14+.
 - Class chests (non-linked) now work again on servers running Minecraft 1.14+.

src/main/java/com/garbagemule/MobArena/util/ItemParser.java

@@ -100,22 +100,28 @@ public class ItemParser
     }
     
     private static ItemStack withPotionMeta(ItemStack stack, String data) {
-        PotionType type = getPotionType(data);
-        if (type == null) {
-            return null;
-        }
-        PotionMeta meta = (PotionMeta) stack.getItemMeta();
-        meta.setBasePotionData(new PotionData(type));
-        stack.setItemMeta(meta);
-        return stack;
-    }
+        PotionType type;
+        boolean extended = false;
+        boolean upgraded = false;
 
-    private static PotionType getPotionType(String data) {
+        if (data.startsWith("long_")) {
+            extended = true;
+            data = data.substring(5);
+        }
+        if (data.startsWith("strong_")) {
+            upgraded = true;
+            data = data.substring(7);
+        }
         try {
-            return PotionType.valueOf(data.toUpperCase());
+            type = PotionType.valueOf(data.toUpperCase());
         } catch (IllegalArgumentException e) {
             return null;
         }
+
+        PotionMeta meta = (PotionMeta) stack.getItemMeta();
+        meta.setBasePotionData(new PotionData(type, extended, upgraded));
+        stack.setItemMeta(meta);
+        return stack;
     }
 
     private static Optional<Material> getType(String item) {