src/protocolsupport/api/ProtocolSupportAPI.java

package protocolsupport.api;

import java.math.BigInteger;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.commons.lang3.Validate;
import org.bukkit.entity.Player;

import protocolsupport.protocol.storage.ProtocolStorage;

public class ProtocolSupportAPI {

	private static final BigInteger apiversion = BigInteger.valueOf(8);
	/**
	 * Returns ProtocolSupport API version <br>
	 * This number is incremented every time API changes (behavior change, method/field added/removed)
	 * @return API version
	 */
	public static BigInteger getAPIVersion() {
		return apiversion;
	}

	/**
	 * Returns player {@link ProtocolVersion} <br>
	 * Returns {@link ProtocolVersion#UNKNOWN} if player is not online or is not a real player
	 * @param player player
	 * @return player protocol version or UNKNOWN
	 */
	public static ProtocolVersion getProtocolVersion(Player player) {
		Connection connection = getConnection(player);
		return connection != null ? connection.getVersion() : ProtocolVersion.UNKNOWN;
	}

	/**
	 * Returns {@link ProtocolVersion} of connection with specified address <br>
	 * Returns {@link ProtocolVersion#UNKNOWN} if there is no connection with specified address
	 * @param address address
	 * @return connection protocol version or UNKNOWN
	 */
	public static ProtocolVersion getProtocolVersion(SocketAddress address) {
		Connection connection = getConnection(address);
		return connection != null ? connection.getVersion() : ProtocolVersion.UNKNOWN;
	}

	/**
	 * Returns all currently active connections
	 * @return all currently active connections
	 */
	public static List<Connection> getConnections() {
		return new ArrayList<>(ProtocolStorage.getConnections());
	}

	/**
	 * Returns player {@link Connection} <br>
	 * Returns null if player is not online or is not a real player
	 * @param player player
	 * @return player {@link Connection} or null
	 */
	public static Connection getConnection(Player player) {
		return getConnection(player.spigot().getRawAddress());
	}

	/**
	 * Returns connection with specified address <br>
	 * Returns null if there is no connection with specified address
	 * @param address address
	 * @return {@link Connection} with specified address
	 */
	public static Connection getConnection(SocketAddress address) {
		return ProtocolStorage.getConnection(address);
	}


	private static final Set<ProtocolVersion> enabledVersions = Collections.newSetFromMap(new ConcurrentHashMap<>());
	static {
		enabledVersions.addAll(Arrays.asList(ProtocolVersion.getAllSupported()));
	}

	/**
	 * Enables protocol version support if it was disabled previously <br>
	 * By default all supported versions are enabled
	 * @param version protocol version which support needs to be enabled
	 */
	public static void enableProtocolVersion(ProtocolVersion version) {
		Validate.isTrue(version.isSupported(), "Can't enable support for version that is not supported at all");
		enabledVersions.add(version);
	}

	/**
	 * Disables protocol version support, players with that version won't be able to login to server and ping will report server as unsupported version <br>
	 * Disabling all versions before 1.9 will allow multiple passengers on entity
	 * @param version protocol version which support needs to be disabled
	 */
	public static void disableProtocolVersion(ProtocolVersion version) {
		Validate.isTrue(version.isSupported(), "Can't disable support for version that is not supported at all");
		enabledVersions.remove(version);
	}

	/**
	 * Return true if protocol version support is enabled
	 * @param version protocol version for which support enabled should be checked
	 * @return true if protocol version support is enabled, false otherwise
	 */
	public static boolean isProtocolVersionEnabled(ProtocolVersion version) {
		return enabledVersions.contains(version);
	}

	/**
	 * Returns all currently enabled protocol versions
	 * @return all currently enabled protocol versions
	 */
	public static Collection<ProtocolVersion> getEnabledProtocolVersions() {
		return new ArrayList<>(enabledVersions);
	}

}