TF-EssentialsX/Essentials/src/com/earth2me/essentials/commands/Commandpotion.java

package com.earth2me.essentials.commands;

import com.earth2me.essentials.MetaItemStack;
import com.earth2me.essentials.Potions;
import com.earth2me.essentials.User;
import com.earth2me.essentials.utils.StringUtil;
import org.bukkit.Material;
import org.bukkit.Server;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.PotionMeta;
import org.bukkit.potion.PotionEffect;
import org.bukkit.potion.PotionEffectType;

import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;

import static com.earth2me.essentials.I18n.tl;


public class Commandpotion extends EssentialsCommand {
    public Commandpotion() {
        super("potion");
    }

    @Override
    protected void run(final Server server, final User user, final String commandLabel, final String[] args) throws Exception {
        final ItemStack stack = user.getBase().getItemInHand();

        if (args.length == 0) {
            final Set<String> potionslist = new TreeSet<>();
            for (Map.Entry<String, PotionEffectType> entry : Potions.entrySet()) {
                final String potionName = entry.getValue().getName().toLowerCase(Locale.ENGLISH);
                if (potionslist.contains(potionName) || (user.isAuthorized("essentials.potion." + potionName))) {
                    potionslist.add(entry.getKey());
                }
            }
            throw new NotEnoughArgumentsException(tl("potions", StringUtil.joinList(potionslist.toArray())));
        }

        if (stack.getType() == Material.POTION) {
            PotionMeta pmeta = (PotionMeta) stack.getItemMeta();
            if (args.length > 0) {
                if (args[0].equalsIgnoreCase("clear")) {
                    pmeta.clearCustomEffects();
                    stack.setItemMeta(pmeta);
                } else if (args[0].equalsIgnoreCase("apply") && user.isAuthorized("essentials.potion.apply")) {
                    for (PotionEffect effect : pmeta.getCustomEffects()) {
                        effect.apply(user.getBase());
                    }
                } else if (args.length < 3) {
                    throw new NotEnoughArgumentsException();
                } else {
                    final MetaItemStack mStack = new MetaItemStack(stack);
                    for (String arg : args) {
                        mStack.addPotionMeta(user.getSource(), true, arg, ess);
                    }
                    if (mStack.completePotion()) {
                        pmeta = (PotionMeta) mStack.getItemStack().getItemMeta();
                        stack.setItemMeta(pmeta);
                    } else {
                        user.sendMessage(tl("invalidPotion"));
                        throw new NotEnoughArgumentsException();
                    }
                }
            }

        } else {
            throw new Exception(tl("holdPotion"));
        }
    }
}