envoy/common/src/main/java/envoy/event/GroupResize.java

package envoy.event;

import envoy.data.Contact;
import envoy.data.Group;
import envoy.data.User;

/**
 * This event is used to communicate changes in the group size between client
 * and server.<br>
 * Possible actions are adding or removing certain {@link User}s to or from a
 * certain {@link Group}.
 * <br>
 * Project: <strong>envoy-common</strong><br>
 * File: <strong>GroupResize.java</strong><br>
 * Created: <strong>25 Mar 2020</strong><br>
 *
 * @author Leon Hofmeister
 * @since Envoy Common v0.1-beta
 */
public class GroupResize extends Event<User> {

	private final long				groupID;
	private final ElementOperation	operation;

	private static final long serialVersionUID = 0L;

	/**
	 * Initializes a {@link GroupResize} through a Contact where the name has
	 * already been set.
	 *
	 * @param user      the {@link User} who wants to join or leave a group
	 * @param group     the {@link Group} he wants to join or leave
	 * @param operation describes what to do with the given user:<br>
	 *                  add him to this group or remove him from it
	 * @since Envoy Common v0.2-alpha
	 */
	public GroupResize(User user, Group group, ElementOperation operation) {
		super(user);
		if (group.getContacts().contains(user)) {
			if (operation.equals(ElementOperation.ADD)) throw new IllegalArgumentException(
					"Cannot add " + user + " to group " + group.getID() + " because he is already a member of this group");
		} else if (operation.equals(ElementOperation.REMOVE))
			throw new IllegalArgumentException("Cannot remove " + user + " from group " + group.getID() + " because he is no part of this group");
		groupID			= group.getID();
		this.operation	= operation;
	}

	/**
	 * @return the ID of the {@link Contact} this event is related to
	 * @since Envoy Common v0.2-alpha
	 */
	public long getGroupID() { return groupID; }

	/**
	 * @return the operationType
	 * @since Envoy Common v0.1-beta
	 */
	public ElementOperation getOperation() { return operation; }

	/**
	 * {@inheritDoc}
	 */
	@Override
	public String toString() { return String.format("GroupResize[userid=%d,groupid=%d,operation=%s]", get(), groupID, operation); }
}