public class CommandHandler implements CommandExecutor {

    public static HashMap<UUID, Integer> cooldownTime = new HashMap<UUID, Integer>();
    public static HashMap<UUID, BukkitRunnable> cooldownTask = new HashMap<UUID, BukkitRunnable>();

    public boolean onCommand(CommandSender sender, Command cmd, String command, String[] args) {
        if (!(sender instanceof Player)) {
            sender.sendMessage("You aint no player!");
            return false;
        }
        final Player p = (Player) sender;
        if (command.equalsIgnoreCase("smelt")) {
            if (cooldownTime.containsKey(p.getUniqueId())) {
                p.sendMessage(ChatColor.AQUA + "You must wait " + cooldownTime.get(p.getUniqueId()) + " seconds before using that command again!");
                return true;
            }
            cooldownTime.put(p.getUniqueId(), 5 * 60 * 20);
            cooldownTask.put(p.getUniqueId(), new BukkitRunnable() {
                public void run() {
                    cooldownTime.put(p.getUniqueId(), cooldownTime.get(p.getUniqueId()) - 1);
                    if (cooldownTime.get(p.getUniqueId()) == 0) {
                        cooldownTime.remove(p.getUniqueId());
                        cooldownTask.remove(p.getUniqueId());
                        cancel();
                    }
                }
            });
            cooldownTask.get(p.getUniqueId()).runTaskTimer(Bukkit.getPluginManager().getPlugin("Smelt"), 20, 20);

            for (ItemStack is : p.getInventory().getContents()) {
                if (is == null) continue;
                if (is.getType() == null) continue;
                int amount = is.getAmount();

                switch (is.getType()) {
                case DIAMOND_ORE:
                    p.getInventory().remove(is);
                    p.getInventory().addItem(new ItemStack(Material.DIAMOND, amount));
                    break;
                case EMERALD_ORE:
                    p.getInventory().remove(is);
                    p.getInventory().addItem(new ItemStack(Material.EMERALD, amount));
                    break;
                case GOLD_ORE:
                    p.getInventory().remove(is);
                    p.getInventory().addItem(new ItemStack(Material.GOLD_INGOT, amount));
                    break;
                case IRON_ORE:
                    p.getInventory().remove(is);
                    p.getInventory().addItem(new ItemStack(Material.IRON_INGOT, amount));
                    break;
                case COAL_ORE:
                    p.getInventory().remove(is);
                    p.getInventory().addItem(new ItemStack(Material.COAL, amount));
                    break;
                }
            }
            p.sendMessage(ChatColor.AQUA + "You have smelted your inventory!");
            return true;
        }
        return false;
    }

}