Advanced Features

/**
 * Main entry point for collaboration features
 * Provides real-time synchronization across multiple users
 */
class CollaborationEngine {
    /**
     * Gets the collaboration engine instance
     * @return CollaborationEngine instance
     */
    static CollaborationEngine getInstance();

    /**
     * Configures the collaboration engine
     * @param service - Vaadin service
     * @param configuration - Engine configuration
     */
    static void configure(VaadinService service, CollaborationEngineConfiguration configuration);

    /**
     * Gets user info from request
     * @param request - Vaadin request
     * @return UserInfo instance
     */
    UserInfo getUserInfo(VaadinRequest request);

    /**
     * Creates a collaborative binder
     * @param session - Vaadin session
     * @param beanType - Bean class type
     * @return CollaborationBinder instance
     */
    CollaborationBinder createBinder(VaadinSession session, Class<?> beanType);
}

/**
 * Configuration for collaboration engine
 */
class CollaborationEngineConfiguration {
    /**
     * Sets whether to automatically activate push
     * @param automaticallyActivatePush - true to auto-activate
     */
    void setAutomaticallyActivatePush(boolean automaticallyActivatePush);

    /**
     * Sets the license key for production use
     * @param licenseKey - License key string
     */
    void setLicenseKey(String licenseKey);
}

/**
 * User information for collaboration
 */
class UserInfo {
    UserInfo(String userId);
    UserInfo(String userId, String name);
    UserInfo(String userId, String name, String image);
    String getId();
    String getName();
    String getImage();
    String getAbbreviation();
    String getColorIndex();
}

/**
 * Avatar group showing active collaborators
 */
class CollaborationAvatarGroup extends Component {
    /**
     * Creates collaborative avatar group
     * @param localUser - Local user info
     * @param topicId - Topic identifier
     */
    CollaborationAvatarGroup(UserInfo localUser, String topicId);

    /**
     * Creates with engine instance
     * @param localUser - Local user info
     * @param engine - Collaboration engine
     * @param topicId - Topic identifier
     */
    CollaborationAvatarGroup(UserInfo localUser, CollaborationEngine engine, String topicId);

    /**
     * Sets maximum avatars visible
     * @param maxItemsVisible - Maximum count
     */
    void setMaxItemsVisible(int maxItemsVisible);

    /**
     * Sets whether to show own user
     * @param ownUser - true to show own user
     */
    void setOwnUser(boolean ownUser);
}

/**
 * Collaborative form binder with real-time synchronization
 */
class CollaborationBinder extends Binder {
    /**
     * Creates collaborative binder
     * @param beanType - Bean class type
     * @param localUser - Local user info
     * @param topicId - Topic identifier
     */
    CollaborationBinder(Class<?> beanType, UserInfo localUser, String topicId);

    /**
     * Sets the collaboration topic
     * @param topicId - Topic identifier
     * @param defaultValue - Supplier for default value
     */
    void setTopic(String topicId, Supplier<?> defaultValue);

    /**
     * Adds value change listener for collaborative updates
     * @param listener - Value change listener
     * @return Registration for removing listener
     */
    Registration addValueChangeListener(ValueChangeListener listener);
}

/**
 * Collaborative list with real-time synchronization
 */
class CollaborationList<T> {
    /**
     * Creates collaborative list
     * @param engine - Collaboration engine
     * @param localUser - Local user info
     * @param topicId - Topic identifier
     * @param itemType - Item class type
     */
    CollaborationList(CollaborationEngine engine, UserInfo localUser, String topicId, Class<T> itemType);

    /**
     * Inserts item at index
     * @param index - Insert position
     * @param item - Item to insert
     */
    void insertItem(int index, T item);

    /**
     * Appends item to end
     * @param item - Item to append
     */
    void appendItem(T item);

    /**
     * Removes item at index
     * @param index - Item index
     */
    void removeItem(int index);

    /**
     * Updates item at index
     * @param index - Item index
     * @param item - Updated item
     */
    void setItem(int index, T item);

    /**
     * Gets item at index
     * @param index - Item index
     * @return Item at index
     */
    T getItem(int index);

    /**
     * Gets list size
     * @return Size of list
     */
    int getSize();

    /**
     * Subscribes to collaborative changes
     * @param subscriber - Change subscriber
     * @return Registration for removing subscription
     */
    Registration subscribe(CollaborationListSubscriber<T> subscriber);
}

/**
 * Subscriber for collaborative list changes
 */
interface CollaborationListSubscriber<T> {
    /**
     * Called when item is inserted
     * @param index - Insert position
     * @param item - Inserted item
     * @param user - User who inserted
     */
    void onItemInserted(int index, T item, UserInfo user);

    /**
     * Called when item is updated
     * @param index - Item index
     * @param item - Updated item
     * @param user - User who updated
     */
    void onItemUpdated(int index, T item, UserInfo user);

    /**
     * Called when item is removed
     * @param index - Item index
     * @param item - Removed item
     * @param user - User who removed
     */
    void onItemRemoved(int index, T item, UserInfo user);
}

/**
 * Collaborative message list for real-time chat
 */
class CollaborationMessageList {
    /**
     * Creates collaborative message list
     * @param localUser - Local user info
     * @param topicId - Topic identifier
     * @param messageList - MessageList component
     * @param messageInput - MessageInput component
     */
    CollaborationMessageList(UserInfo localUser, String topicId,
                             MessageList messageList, MessageInput messageInput);

    /**
     * Sets custom submit handler
     * @param submitter - Submit handler
     */
    void setSubmitter(BiConsumer<MessageInput, MessageListItem> submitter);
}

// Collaborative avatar group
UserInfo localUser = new UserInfo("user-123", "John Doe", "/images/john.png");
CollaborationAvatarGroup avatarGroup = new CollaborationAvatarGroup(
    localUser, "document-456"
);
avatarGroup.setMaxItemsVisible(5);
add(avatarGroup);

// Collaborative form
UserInfo localUser = new UserInfo("user-123", "John Doe");
CollaborationBinder<Person> binder = new CollaborationBinder<>(
    Person.class, localUser, "person-789"
);
TextField nameField = new TextField("Name");
TextField emailField = new TextField("Email");

binder.forField(nameField).bind(Person::getName, Person::setName);
binder.forField(emailField).bind(Person::getEmail, Person::setEmail);

binder.setTopic("person-789", Person::new);

// Collaborative list
UserInfo localUser = new UserInfo("user-123", "John Doe");
CollaborationList<Task> taskList = new CollaborationList<>(
    CollaborationEngine.getInstance(),
    localUser, "tasks-project-456", Task.class
);

// Add item
taskList.appendItem(new Task("Review documentation"));

// Subscribe to changes
taskList.subscribe(new CollaborationListSubscriber<Task>() {
    @Override
    public void onItemInserted(int index, Task item, UserInfo user) {
        Notification.show(user.getName() + " added: " + item.getTitle());
    }

    @Override
    public void onItemUpdated(int index, Task item, UserInfo user) {
        Notification.show(user.getName() + " updated: " + item.getTitle());
    }

    @Override
    public void onItemRemoved(int index, Task item, UserInfo user) {
        Notification.show(user.getName() + " removed: " + item.getTitle());
    }
});

// Collaborative message list
UserInfo localUser = new UserInfo("user-123", "John Doe");
MessageList messageList = new MessageList();
MessageInput messageInput = new MessageInput();

CollaborationMessageList collaborationMessageList = new CollaborationMessageList(
    localUser, "chat-topic-123", messageList, messageInput
);

// Optional: custom submit handler
collaborationMessageList.setSubmitter((input, item) -> {
    // Custom submission logic
    item.setText(input.getValue());
    item.setTime(Instant.now());
    item.setUserName(localUser.getName());
});

add(messageList, messageInput);

class MessageList extends Component {
    MessageList();
    void setItems(List<MessageListItem> items);
}

class MessageListItem implements Serializable {
    MessageListItem();
    MessageListItem(String text);
    MessageListItem(String text, Instant time, String userName);
    void setText(String text);
    void setTime(Instant time);
    void setUserName(String userName);
    void setUserImage(String userImage);
    void setUserColorIndex(Integer colorIndex);
    void setUserAbbreviation(String abbreviation);
}

class MessageInput extends Component {
    MessageInput();
    void setPlaceholder(String placeholder);
    void setI18n(MessageInputI18n i18n);
    Registration addSubmitListener(ComponentEventListener<SubmitEvent> listener);
}

class SubmitEvent extends ComponentEvent<MessageInput> {
    String getValue();
}

class MessageInputI18n implements Serializable {
    void setSend(String send);
    void setMessage(String message);
}

@Route("chat")
public class ChatView extends VerticalLayout {
    private MessageList messageList;
    private MessageInput messageInput;
    private List<MessageListItem> messages = new ArrayList<>();

    public ChatView() {
        messageList = new MessageList();
        messageList.setHeight("500px");

        messageInput = new MessageInput();
        messageInput.addSubmitListener(e -> addMessage(e.getValue()));

        add(messageList, messageInput);
        setSizeFull();
    }

    private void addMessage(String text) {
        MessageListItem msg = new MessageListItem(
            text, Instant.now(), "Current User"
        );
        msg.setUserAbbreviation("CU");
        msg.setUserColorIndex(2);
        messages.add(msg);
        messageList.setItems(messages);
        messageInput.setValue("");
    }
}

enum ValueChangeMode {
    EAGER,      // On every keystroke
    LAZY,       // On blur
    TIMEOUT,    // After timeout
    ON_BLUR,    // On blur
    ON_CHANGE   // On change
}

TextField searchField = new TextField("Search");
searchField.setValueChangeMode(ValueChangeMode.LAZY);
searchField.setValueChangeTimeout(500);
searchField.addValueChangeListener(e -> performSearch(e.getValue()));

interface ComponentEventListener<E extends ComponentEvent<?>> extends Serializable {
    void onComponentEvent(E event);
}

class ClickEvent<T extends Component> extends ComponentEvent<T> {
    int getClientX();
    int getClientY();
    boolean isAltKey();
    boolean isCtrlKey();
    boolean isShiftKey();
}

class ComponentValueChangeEvent<C extends Component, V>
        extends ComponentEvent<C> implements HasValue.ValueChangeEvent<V> {
    V getOldValue();
    V getValue();
    boolean isFromClient();
}

interface Registration extends Serializable {
    void remove();
}

Button button = new Button("Save", e -> {
    if (e.isCtrlKey()) {
        saveAsDraft();
    } else {
        save();
    }
});

TextField field = new TextField("Name");
field.addValueChangeListener(e -> {
    String oldValue = e.getOldValue();
    String newValue = e.getValue();
    if (!newValue.equals(oldValue)) {
        validate(newValue);
    }
});

@FunctionalInterface
interface ValueProvider<SOURCE, TARGET> extends SerializableFunction<SOURCE, TARGET> {
    TARGET apply(SOURCE source);
}

@FunctionalInterface
interface Setter<BEAN, VALUE> extends BiConsumer<BEAN, VALUE>, Serializable {
    void accept(BEAN bean, VALUE value);
}

@FunctionalInterface
interface ItemLabelGenerator<T> extends SerializableFunction<T, String> {
    String apply(T item);
}

@FunctionalInterface
interface SerializableFunction<T, R> extends Function<T, R>, Serializable {
    R apply(T t);
}

@FunctionalInterface
interface SerializableConsumer<T> extends Consumer<T>, Serializable {
    void accept(T t);
}

@FunctionalInterface
interface SerializablePredicate<T> extends Predicate<T>, Serializable {
    boolean test(T t);
}