package envoy.client.ui.controller;

import static java.util.function.Predicate.not;

import java.util.stream.Collectors;

import javafx.application.Platform;
import javafx.fxml.FXML;
import javafx.scene.control.*;
import javafx.scene.control.Alert.AlertType;

import envoy.client.data.Chat;
import envoy.client.data.LocalDB;
import envoy.client.event.BackEvent;
import envoy.client.event.LoadGroupCreationEvent;
import envoy.client.event.SendEvent;
import envoy.client.ui.SceneContext;
import envoy.client.ui.listcell.ContactControl;
import envoy.client.ui.listcell.ListCellFactory;
import envoy.data.Contact;
import envoy.data.Group;
import envoy.data.User;
import envoy.event.EventBus;
import envoy.event.GroupCreation;
import envoy.util.Bounds;

/**
 * Provides a group creation interface. A group name can be entered in the text
 * field at the top. Available users (local chat recipients) are displayed
 * inside a list and can be selected (multiple selection available).
 * <p>
 * When the group creation button is pressed, a {@link GroupCreation} is sent to
 * the server. This controller enforces a valid group name and a non-empty
 * member list (excluding the client user).
 * <p>
 * Project: <strong>envoy-client</strong><br>
 * File: <strong>GroupCreationScene.java</strong><br>
 * Created: <strong>07.06.2020</strong><br>
 *
 * @author Maximilian K&auml;fer
 * @since Envoy Client v0.1-beta
 */
public class GroupCreationTab {

	@FXML
	private Button createButton;

	@FXML
	private TextArea groupNameField;

	@FXML
	private ListView<User> userList;

	private LocalDB localDB;

	private static final EventBus eventBus = EventBus.getInstance();

	@FXML
	private void initialize() {
		userList.setCellFactory(new ListCellFactory<>(ContactControl::new));
		userList.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
		
		eventBus.register(LoadGroupCreationEvent.class, e -> {
			createButton.setDisable(true);
			this.localDB = e.get();
			userList.getItems().clear();
			Platform.runLater(() -> userList.getItems()
					.addAll(localDB.getChats()
						.stream()
						.map(Chat::getRecipient)
						.filter(User.class::isInstance)
						.filter(not(localDB.getUser()::equals))
						.map(User.class::cast)
						.collect(Collectors.toList())));
		});
	}

	/**
	 * Enables the {@code createButton} if at least one contact is selected.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void userListClicked() {
		createButton.setDisable(userList.getSelectionModel().isEmpty() || groupNameField.getText().isBlank());
	}

	/**
	 * Checks, whether the {@code createButton} can be enabled because text is
	 * present in the text field.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void textUpdated() { createButton.setDisable(userList.getSelectionModel().isEmpty() || groupNameField.getText().isBlank()); }

	/**
	 * Sends a {@link GroupCreation} to the server and closes this scene.
	 * <p>
	 * If the given group name is not valid, an error is displayed instead.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void createButtonClicked() {
		final var name = groupNameField.getText();
		if (!Bounds.isValidContactName(name)) {
			new Alert(AlertType.ERROR, "The entered group name is not valid (" + Bounds.CONTACT_NAME_PATTERN + ")").showAndWait();
			groupNameField.clear();
		} else if (groupNameAlreadyPresent(name)) {
			final var alert = new Alert(AlertType.WARNING, "You already have a group with that name.", ButtonType.OK, ButtonType.CANCEL);
			alert.setTitle("Create Group?");
			alert.setHeaderText("Proceed?");
			alert.showAndWait().filter(btn -> btn == ButtonType.OK).ifPresent(btn -> createGroup(name));
		} else {
			new Alert(AlertType.INFORMATION, String.format("Group '%s' successfully created.", name)).showAndWait();
			createGroup(name);
		}
		eventBus.dispatch(new BackEvent());
	}

	/**
	 * Creates a new group with the given name and all selected members.<br>
	 * Additionally pops the scene automatically.
	 *
	 * @param name the chosen group name
	 * @since Envoy Client v0.1-beta
	 */
	private void createGroup(String name) {
		eventBus.dispatch(new SendEvent(
				new GroupCreation(name, userList.getSelectionModel().getSelectedItems().stream().map(User::getID).collect(Collectors.toSet()))));
	}

	/**
	 * Returns true if the proposed group name is already present in the users
	 * {@code LocalDB}.
	 *
	 * @param newName the chosen group name
	 * @return true if this name is already present
	 * @since Envoy Client v0.1-beta
	 */
	public boolean groupNameAlreadyPresent(String newName) {
		return localDB.getChats()
			.stream()
			.map(Chat::getRecipient)
			.filter(Group.class::isInstance)
			.map(Contact::getName)
			.anyMatch(newName::equals);
	}

	@FXML
	private void backButtonClicked() { eventBus.dispatch(new BackEvent()); }
}