Spigot Menu

Menu.java

import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.HandlerList;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.event.inventory.InventoryCloseEvent;
import org.bukkit.event.inventory.InventoryType;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.InventoryHolder;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
import org.bukkit.plugin.Plugin;
import org.jetbrains.annotations.Contract;
import org.jetbrains.annotations.NotNull;

import java.util.HashMap;
import java.util.Map;
import java.util.function.Consumer;

public abstract class Menu implements InventoryHolder, Listener
{

	private boolean loaded;

	protected final Plugin plugin;

	protected final Inventory                                   inventory;
	protected final Map<Integer, Consumer<InventoryClickEvent>> consumers = new HashMap<>();


	protected Menu(@NotNull final Plugin plugin, @NotNull final String title, @NotNull final Size size)
	{
		this.plugin = plugin;
		this.inventory = plugin.getServer().createInventory(this, (size.ordinal() + 1) * 9, color(title));
	}


	@NotNull
	@Override
	public final Inventory getInventory()
	{
		return inventory;
	}

	@NotNull
	public final Map<Integer, Consumer<InventoryClickEvent>> getConsumers()
	{
		return consumers;
	}


	private void load()
	{
		if (loaded)
		{
			return;
		}

		loaded = true;

		plugin.getServer().getPluginManager().registerEvents(this, plugin);
	}

	private void kill()
	{
		if (!loaded)
		{
			return;
		}

		loaded = false;

		HandlerList.unregisterAll(this);

		getConsumers().clear();
		getInventory().clear();
	}


	public final void open(@NotNull final Player player)
	{
		if (!loaded)
		{
			load();
			make();
		}

		player.openInventory(getInventory());
		opened(player);
	}


	protected void make()
	{

	}

	protected void redo()
	{
		consumers.clear();
		getInventory().clear();

		make();
	}


	protected void opened(@NotNull final Player player)
	{

	}

	protected void closed(@NotNull final Player player)
	{

	}


	protected final void slot(final int slot, @NotNull final ItemStack item)
	{
		getInventory().setItem(slot, item);
	}

	protected final void slot(final int slot, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		consumers.put(slot, consumer);
	}

	protected final void slot(final int slot, @NotNull final ItemStack item, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		slot(slot, item);
		slot(slot, consumer);
	}


	protected final void grid(@NotNull final Rows row, @NotNull final Cols col, @NotNull final ItemStack item)
	{
		slot(Grid.from(row, col), item);
	}

	protected final void grid(@NotNull final Rows row, @NotNull final Cols col, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		slot(Grid.from(row, col), consumer);
	}

	protected final void grid(@NotNull final Rows row, @NotNull final Cols col, @NotNull final ItemStack item, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		grid(row, col, item);
		grid(row, col, consumer);
	}


	protected final void grid(@NotNull final Rows row, @NotNull final ItemStack item)
	{
		for (final Cols col : Cols.COLS)
		{
			final int slot = Grid.from(row, col);
			if (slot > getInventory().getSize())
			{
				break;
			}
			if (getInventory().getItem(slot) != null)
			{
				continue;
			}

			slot(slot, item);
		}
	}

	protected final void grid(@NotNull final Rows row, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		for (final Cols col : Cols.COLS)
		{
			final int slot = Grid.from(row, col);
			if (slot > getInventory().getSize())
			{
				break;
			}
			if (consumers.containsKey(slot))
			{
				continue;
			}

			slot(slot, consumer);
		}
	}

	protected final void grid(@NotNull final Rows row, @NotNull final ItemStack item, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		for (final Cols col : Cols.COLS)
		{
			final int slot = Grid.from(row, col);
			if (slot > getInventory().getSize())
			{
				break;
			}
			if (consumers.containsKey(slot) || getInventory().getItem(slot) != null)
			{
				continue;
			}

			slot(slot, item);
			slot(slot, consumer);
		}
	}


	protected final void grid(@NotNull final Cols col, @NotNull final ItemStack item)
	{
		for (final Rows row : Rows.ROWS)
		{
			final int slot = Grid.from(row, col);
			if (slot > getInventory().getSize())
			{
				break;
			}
			if (getInventory().getItem(slot) != null)
			{
				continue;
			}

			slot(slot, item);
		}
	}

	protected final void grid(@NotNull final Cols col, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		for (final Rows row : Rows.ROWS)
		{
			final int slot = Grid.from(row, col);
			if (slot > getInventory().getSize())
			{
				break;
			}
			if (consumers.containsKey(slot))
			{
				continue;
			}

			slot(slot, consumer);
		}
	}

	protected final void grid(@NotNull final Cols col, @NotNull final ItemStack item, @NotNull final Consumer<InventoryClickEvent> consumer)
	{
		for (final Rows row : Rows.ROWS)
		{
			final int slot = Grid.from(row, col);
			if (slot > getInventory().getSize())
			{
				break;
			}
			if (consumers.containsKey(slot) || getInventory().getItem(slot) != null)
			{
				continue;
			}

			slot(slot, item);
			slot(slot, consumer);
		}
	}


	@EventHandler(priority = EventPriority.HIGH, ignoreCancelled = true)
	public final void onClick(@NotNull final InventoryClickEvent event)
	{
		if (event.getView().getTopInventory().getHolder() != this)
		{
			// if we aren't the holder, do nothing
			return;
		}

		if (event.getSlotType() == InventoryType.SlotType.OUTSIDE || event.getRawSlot() > getInventory().getSize())
		{
			// if they click outside of the inventory, or the slot the click isn't in this inventory, do nothing
			return;
		}


		final Consumer<InventoryClickEvent> consumer = consumers.get(event.getRawSlot());
		if (consumer == null)
		{
			// if there is no consumer for this slot, do nothing
			return;
		}

		consumer.accept(event);
	}

	@EventHandler
	public final void onClose(@NotNull final InventoryCloseEvent event)
	{
		if (event.getView().getTopInventory().getHolder() != this)
		{
			// if we aren't the holder, do nothing
			return;
		}


		if (event.getPlayer() instanceof Player)
		{
			closed(((Player) event.getPlayer()));
		}

		if (getInventory().getViewers().size() > 1)
		{
			// if there is more than one player viewing this inventory, do nothing
			return;
		}

		kill();
	}


	@NotNull
	public static String color(@NotNull final String text)
	{
		return ChatColor.translateAlternateColorCodes('&', text);
	}

	@NotNull
	public static ItemStack item(@NotNull final Material type)
	{
		return item(type, 1);
	}

	@NotNull
	public static ItemStack item(@NotNull final Material type, final int amount)
	{
		return new ItemStack(type, amount);
	}

	@NotNull
	public static ItemStack item(@NotNull final Material type, final int amount, @NotNull final Consumer<ItemMeta> consumer)
	{
		return meta(item(type, amount), consumer);
	}

	@NotNull
	@Contract("_, _ -> param1")
	public static ItemStack meta(@NotNull final ItemStack item, @NotNull final Consumer<ItemMeta> consumer)
	{
		final ItemMeta meta = item.getItemMeta();
		consumer.accept(meta);

		item.setItemMeta(meta);

		return item;
	}


	public enum Size
	{
		ROWS_1,
		ROWS_2,
		ROWS_3,
		ROWS_4,
		ROWS_5,
		ROWS_6,
	}

	/**
	 *     C_1 C_2 C_3 C_4 C_5 C_6 C_7 C_8 C_9
	 *    ╔═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╗
	 * R_1║  0║  1║  2║  3║  4║  5║  6║  7║  8║
	 *    ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
	 * R_2║  9║ 10║ 11║ 12║ 13║ 14║ 15║ 16║ 17║
	 *    ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
	 * R_3║ 18║ 19║ 20║ 21║ 22║ 23║ 24║ 25║ 26║
	 *    ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
	 * R_4║ 27║ 28║ 29║ 30║ 31║ 32║ 33║ 34║ 35║
	 *    ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
	 * R_5║ 36║ 37║ 38║ 39║ 40║ 41║ 42║ 43║ 44║
	 *    ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
	 * R_6║ 45║ 46║ 47║ 48║ 49║ 50║ 51║ 52║ 53║
	 *    ╚═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╝
	 */
	public enum Grid
	{
		;


		public static int from(@NotNull final Rows row, @NotNull final Cols col)
		{
			return (row.ordinal() * 9) + col.ordinal();
		}

		@NotNull
		@Contract(value = "_ -> new", pure = true)
		public static RaC into(final int slot)
		{
			final int row = slot / 9;
			final int col = slot - row * 9;

			return new RaC(Rows.ROWS[row], Cols.COLS[col]);
		}


		public static final class RaC
		{

			public final Rows row;
			public final Cols col;


			private RaC(final Rows row, final Cols col)
			{
				this.row = row;
				this.col = col;
			}

		}

	}

	public enum Rows
	{
		R_1,
		R_2,
		R_3,
		R_4,
		R_5,
		R_6;

		public static final Rows[] ROWS = values();

	}

	public enum Cols
	{
		C_1,
		C_2,
		C_3,
		C_4,
		C_5,
		C_6,
		C_7,
		C_8,
		C_9;

		public static final Cols[] COLS = values();

	}

}