package org.bukkit.plugin.messaging;

import org.bukkit.entity.Player;
import org.bukkit.plugin.Plugin;

import java.util.Set;

/**
 * A class responsible for managing the registrations of plugin channels and
 * their listeners.
 */
public interface Messenger
{

	/**
	 * Represents the largest size that an individual Plugin Message may be.
	 */
	public static final int MAX_MESSAGE_SIZE = 32766;

	/**
	 * Represents the largest size that a Plugin Channel may be.
	 */
	public static final int MAX_CHANNEL_SIZE = 20; // Cauldron - Vanilla increased limit of C17PacketCustomPayload size from 16 -> 20 in 1.7

	/**
	 * Checks if the specified channel is a reserved name.
	 *
	 * @param channel Channel name to check.
	 * @return True if the channel is reserved, otherwise false.
	 * @throws IllegalArgumentException Thrown if channel is null.
	 */
	public boolean isReservedChannel(String channel);

	/**
	 * Registers the specific plugin to the requested outgoing plugin channel,
	 * allowing it to send messages through that channel to any clients.
	 *
	 * @param plugin  Plugin that wishes to send messages through the channel.
	 * @param channel Channel to register.
	 * @throws IllegalArgumentException Thrown if plugin or channel is null.
	 */
	public void registerOutgoingPluginChannel(Plugin plugin, String channel);

	/**
	 * Unregisters the specific plugin from the requested outgoing plugin
	 * channel, no longer allowing it to send messages through that channel to
	 * any clients.
	 *
	 * @param plugin  Plugin that no longer wishes to send messages through the
	 *                channel.
	 * @param channel Channel to unregister.
	 * @throws IllegalArgumentException Thrown if plugin or channel is null.
	 */
	public void unregisterOutgoingPluginChannel(Plugin plugin, String channel);

	/**
	 * Unregisters the specific plugin from all outgoing plugin channels, no
	 * longer allowing it to send any plugin messages.
	 *
	 * @param plugin Plugin that no longer wishes to send plugin messages.
	 * @throws IllegalArgumentException Thrown if plugin is null.
	 */
	public void unregisterOutgoingPluginChannel(Plugin plugin);

	/**
	 * Registers the specific plugin for listening on the requested incoming
	 * plugin channel, allowing it to act upon any plugin messages.
	 *
	 * @param plugin   Plugin that wishes to register to this channel.
	 * @param channel  Channel to register.
	 * @param listener Listener to receive messages on.
	 * @return The resulting registration that was made as a result of this
	 * method.
	 * @throws IllegalArgumentException Thrown if plugin, channel or listener
	 *                                  is null, or the listener is already registered for this channel.
	 */
	public PluginMessageListenerRegistration registerIncomingPluginChannel(Plugin plugin, String channel, PluginMessageListener listener);

	/**
	 * Unregisters the specific plugin's listener from listening on the
	 * requested incoming plugin channel, no longer allowing it to act upon
	 * any plugin messages.
	 *
	 * @param plugin   Plugin that wishes to unregister from this channel.
	 * @param channel  Channel to unregister.
	 * @param listener Listener to stop receiving messages on.
	 * @throws IllegalArgumentException Thrown if plugin, channel or listener
	 *                                  is null.
	 */
	public void unregisterIncomingPluginChannel(Plugin plugin, String channel, PluginMessageListener listener);

	/**
	 * Unregisters the specific plugin from listening on the requested
	 * incoming plugin channel, no longer allowing it to act upon any plugin
	 * messages.
	 *
	 * @param plugin  Plugin that wishes to unregister from this channel.
	 * @param channel Channel to unregister.
	 * @throws IllegalArgumentException Thrown if plugin or channel is null.
	 */
	public void unregisterIncomingPluginChannel(Plugin plugin, String channel);

	/**
	 * Unregisters the specific plugin from listening on all plugin channels
	 * through all listeners.
	 *
	 * @param plugin Plugin that wishes to unregister from this channel.
	 * @throws IllegalArgumentException Thrown if plugin is null.
	 */
	public void unregisterIncomingPluginChannel(Plugin plugin);

	/**
	 * Gets a set containing all the outgoing plugin channels.
	 *
	 * @return List of all registered outgoing plugin channels.
	 */
	public Set<String> getOutgoingChannels();

	/**
	 * Gets a set containing all the outgoing plugin channels that the
	 * specified plugin is registered to.
	 *
	 * @param plugin Plugin to retrieve channels for.
	 * @return List of all registered outgoing plugin channels that a plugin
	 * is registered to.
	 * @throws IllegalArgumentException Thrown if plugin is null.
	 */
	public Set<String> getOutgoingChannels(Plugin plugin);

	/**
	 * Gets a set containing all the incoming plugin channels.
	 *
	 * @return List of all registered incoming plugin channels.
	 */
	public Set<String> getIncomingChannels();

	/**
	 * Gets a set containing all the incoming plugin channels that the
	 * specified plugin is registered for.
	 *
	 * @param plugin Plugin to retrieve channels for.
	 * @return List of all registered incoming plugin channels that the plugin
	 * is registered for.
	 * @throws IllegalArgumentException Thrown if plugin is null.
	 */
	public Set<String> getIncomingChannels(Plugin plugin);

	/**
	 * Gets a set containing all the incoming plugin channel registrations
	 * that the specified plugin has.
	 *
	 * @param plugin Plugin to retrieve registrations for.
	 * @return List of all registrations that the plugin has.
	 * @throws IllegalArgumentException Thrown if plugin is null.
	 */
	public Set<PluginMessageListenerRegistration> getIncomingChannelRegistrations(Plugin plugin);

	/**
	 * Gets a set containing all the incoming plugin channel registrations
	 * that are on the requested channel.
	 *
	 * @param channel Channel to retrieve registrations for.
	 * @return List of all registrations that are on the channel.
	 * @throws IllegalArgumentException Thrown if channel is null.
	 */
	public Set<PluginMessageListenerRegistration> getIncomingChannelRegistrations(String channel);

	/**
	 * Gets a set containing all the incoming plugin channel registrations
	 * that the specified plugin has on the requested channel.
	 *
	 * @param plugin  Plugin to retrieve registrations for.
	 * @param channel Channel to filter registrations by.
	 * @return List of all registrations that the plugin has.
	 * @throws IllegalArgumentException Thrown if plugin or channel is null.
	 */
	public Set<PluginMessageListenerRegistration> getIncomingChannelRegistrations(Plugin plugin, String channel);

	/**
	 * Checks if the specified plugin message listener registration is valid.
	 * <p>
	 * A registration is considered valid if it has not be unregistered and
	 * that the plugin is still enabled.
	 *
	 * @param registration Registration to check.
	 * @return True if the registration is valid, otherwise false.
	 */
	public boolean isRegistrationValid(PluginMessageListenerRegistration registration);

	/**
	 * Checks if the specified plugin has registered to receive incoming
	 * messages through the requested channel.
	 *
	 * @param plugin  Plugin to check registration for.
	 * @param channel Channel to test for.
	 * @return True if the channel is registered, else false.
	 */
	public boolean isIncomingChannelRegistered(Plugin plugin, String channel);

	/**
	 * Checks if the specified plugin has registered to send outgoing messages
	 * through the requested channel.
	 *
	 * @param plugin  Plugin to check registration for.
	 * @param channel Channel to test for.
	 * @return True if the channel is registered, else false.
	 */
	public boolean isOutgoingChannelRegistered(Plugin plugin, String channel);

	/**
	 * Dispatches the specified incoming message to any registered listeners.
	 *
	 * @param source  Source of the message.
	 * @param channel Channel that the message was sent by.
	 * @param message Raw payload of the message.
	 */
	public void dispatchIncomingMessage(Player source, String channel, byte[] message);
}