Skills now always have mana and stamina

src/main/java/net/Indyuce/mmocore/api/skill/Skill.java

@@ -1,23 +1,16 @@
 package net.Indyuce.mmocore.api.skill;
 
-import java.util.ArrayList;
+import net.Indyuce.mmocore.api.player.PlayerData;
-import java.util.Arrays;
+import net.Indyuce.mmocore.api.util.MMOCoreUtils;
-import java.util.HashMap;
+import net.Indyuce.mmocore.api.util.math.formula.IntegerLinearValue;
-import java.util.List;
+import net.Indyuce.mmocore.api.util.math.formula.LinearValue;
-import java.util.Map;
-import java.util.Random;
-import java.util.Set;
-
 import org.apache.commons.lang.Validate;
 import org.bukkit.Material;
 import org.bukkit.configuration.ConfigurationSection;
 import org.bukkit.configuration.file.FileConfiguration;
 import org.bukkit.inventory.ItemStack;
 
-import net.Indyuce.mmocore.api.player.PlayerData;
+import java.util.*;
-import net.Indyuce.mmocore.api.util.MMOCoreUtils;
-import net.Indyuce.mmocore.api.util.math.formula.IntegerLinearValue;
-import net.Indyuce.mmocore.api.util.math.formula.LinearValue;
 
 public abstract class Skill {
     private final String id;
@@ -38,6 +31,10 @@ public abstract class Skill {
 
         Validate.notNull(id, "ID cannot be null");
         Validate.notNull(id, "Name cannot be null");
+
+        // Default modifiers
+        addModifierIfNone("mana", LinearValue.ZERO);
+        addModifierIfNone("stamina", LinearValue.ZERO);
     }
 
     public Skill(String id) {
@@ -88,8 +85,10 @@ public abstract class Skill {
         return icon.clone();
     }
 
-	/*
+    /**
-	 * passive skills do not display any message
+     * Passive skills do not display any message when trying to cast them
+     *
+     * @return If the skill is passive
      */
     public boolean isPassive() {
         return passive;
@@ -103,6 +102,11 @@ public abstract class Skill {
         modifiers.put(modifier, linear);
     }
 
+    public void addModifierIfNone(String mod, LinearValue defaultValue) {
+        if (!hasModifier(mod))
+            addModifier(mod, defaultValue);
+    }
+
     public LinearValue getModifierInfo(String modifier) {
         return modifiers.get(modifier);
     }

src/main/java/net/Indyuce/mmocore/api/util/math/formula/LinearValue.java

@@ -7,11 +7,15 @@ public class LinearValue {
     private final double base, perLevel, min, max;
     private final boolean hasmin, hasmax;
 
+    public static final LinearValue ZERO = new LinearValue(0, 0, 0, 0);
 
-	/*
+    /**
-	 * a number which depends on the player level. it can be used as a skill
+     * A number formula which depends on the player level. It can be used
-	 * modifier to make the ability better depending on the player level or as
+     * to handle skill modifiers so that the ability gets better with the
-	 * an attrribute value to make attributes increase with the player level
+     * skill level, or as an attribute value to make them scale with the class level.
+     *
+     * @param base     Base value
+     * @param perLevel Every level, final value is increased by X
      */
     public LinearValue(double base, double perLevel) {
         this.base = base;
@@ -22,6 +26,16 @@ public class LinearValue {
         max = 0;
     }
 
+    /**
+     * A number formula which depends on the player level. It can be used
+     * to handle skill modifiers so that the ability gets better with the
+     * skill level, or as an attribute value to make them scale with the class level.
+     *
+     * @param base     Base value
+     * @param perLevel Every level, final value is increased by X
+     * @param min      Minimum final value
+     * @param max      Maximum final value
+     */
     public LinearValue(double base, double perLevel, double min, double max) {
         this.base = base;
         this.perLevel = perLevel;
@@ -31,6 +45,11 @@ public class LinearValue {
         this.max = max;
     }
 
+    /**
+     * Copies a linear formula
+     *
+     * @param value Formula to copy
+     */
     public LinearValue(LinearValue value) {
         base = value.base;
         perLevel = value.perLevel;
@@ -40,6 +59,11 @@ public class LinearValue {
         max = value.max;
     }
 
+    /**
+     * Loads a linear formula from a config section
+     *
+     * @param config Config to load the formula from
+     */
     public LinearValue(ConfigurationSection config) {
         base = config.getDouble("base");
         perLevel = config.getDouble("per-level");