Scale fishing drop chance by lure rather than subtracting 1

Fixes mcMMO-Dev/mcMMO#3383
Added config option for lure enchantment modifier
Fixes lure enchantment having no effect on drops from offhand

src/main/java/com/gmail/nossr50/config/Config.java

@@ -178,6 +178,10 @@ public class Config extends AutoUpdateConfigLoader {
             reason.add("Abilities.Limits.Tree_Feller_Threshold should be greater than 0!");
         }
 
+        if (getFishingLureModifier() < 0) {
+            reason.add("Abilities.Fishing.Lure_Modifier should be at least 0!");
+        }
+
         if (getDetonatorItem() == null) {
             reason.add("Skills.Mining.Detonator_Item is invalid!");
         }
@@ -481,6 +485,7 @@ public class Config extends AutoUpdateConfigLoader {
     public boolean getFishingDropsEnabled() { return config.getBoolean("Skills.Fishing.Drops_Enabled", true); }
     public boolean getFishingOverrideTreasures() { return config.getBoolean("Skills.Fishing.Override_Vanilla_Treasures", true); }
     public boolean getFishingExtraFish() { return config.getBoolean("Skills.Fishing.Extra_Fish", true); }
+    public double getFishingLureModifier() { return config.getDouble("Skills.Fishing.Lure_Modifier", 4.0D); }
 
     /* Mining */
     public Material getDetonatorItem() { return Material.matchMaterial(config.getString("Skills.Mining.Detonator_Name", "FLINT_AND_STEEL")); }

src/main/java/com/gmail/nossr50/skills/fishing/FishingManager.java

@@ -478,7 +478,18 @@ public class FishingManager extends SkillManager {
      */
     private FishingTreasure getFishingTreasure() {
         double diceRoll = Misc.getRandom().nextDouble() * 100;
-        diceRoll -= getPlayer().getInventory().getItemInMainHand().getEnchantmentLevel(Enchantment.LUCK);
+        int luck;
+
+        if (getPlayer().getInventory().getItemInMainHand().getType() == Material.FISHING_ROD) {
+            luck = getPlayer().getInventory().getItemInMainHand().getEnchantmentLevel(Enchantment.LUCK);
+        }
+        else {
+            // We know something was caught, so if the rod wasn't in the main hand it must be in the offhand
+        	luck = getPlayer().getInventory().getItemInOffHand().getEnchantmentLevel(Enchantment.LUCK);
+        }
+
+        // Rather than subtracting luck (and causing a minimum 3% chance for every drop), scale by luck.
+        diceRoll *= (1.0 - luck * Config.getInstance().getFishingLureModifier() / 100);
 
         FishingTreasure treasure = null;
 

src/main/resources/config.yml

@@ -330,6 +330,7 @@ Skills:
         Override_Vanilla_Treasures: true
         # Always catch fish, even when treasure is found
         Extra_Fish: false
+        Lure_Modifier: 4.0
     Herbalism:
         Level_Cap: 0
         Prevent_AFK_Leveling: true