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.input.MouseEvent;
import javafx.scene.layout.HBox;

import envoy.client.data.*;
import envoy.client.event.BackEvent;
import envoy.client.ui.control.*;
import envoy.client.ui.listcell.ListCellFactory;
import envoy.data.*;
import envoy.event.GroupCreation;
import envoy.event.contact.ContactOperation;
import envoy.util.Bounds;

import dev.kske.eventbus.*;

/**
 * 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).
 *
 * @author Maximilian K&auml;fer
 * @since Envoy Client v0.1-beta
 */
public class GroupCreationTab implements EventListener {

	@FXML
	private Button createButton;

	@FXML
	private Button cancelButton;

	@FXML
	private TextArea groupNameField;

	@FXML
	private ListView<User> userList;

	@FXML
	private Label errorMessageLabel;

	@FXML
	private Button proceedDuplicateButton;

	@FXML
	private Button cancelDuplicateButton;

	@FXML
	private HBox errorProceedBox;

	@FXML
	private ListView<QuickSelectControl> quickSelectList;

	private String name;

	private final LocalDB localDB = Context.getInstance().getLocalDB();

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

	@FXML
	private void initialize() {
		userList.setCellFactory(new ListCellFactory<>(ContactControl::new));
		createButton.setDisable(true);
		eventBus.registerListener(this);
		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()));
		resizeQuickSelectSpace(0);
		quickSelectList.addEventFilter(MouseEvent.MOUSE_PRESSED, evt -> evt.consume());
	}

	/**
	 * Enables the {@code createButton} if at least one contact is selected.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void userListClicked() {
		if (userList.getSelectionModel().getSelectedItem() != null) {
			quickSelectList.getItems().add(new QuickSelectControl(userList.getSelectionModel().getSelectedItem(), this::removeFromQuickSelection));
			createButton.setDisable(quickSelectList.getItems().isEmpty() || groupNameField.getText().isBlank());
			resizeQuickSelectSpace(60);
			userList.getItems().remove(userList.getSelectionModel().getSelectedItem());
			userList.getSelectionModel().clearSelection();
		}
	}

	/**
	 * 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(quickSelectList.getItems().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() {
		name = groupNameField.getText();
		if (!Bounds.isValidContactName(name)) {
			setErrorMessageLabelSize(30);
			errorMessageLabel.setText("The group name is not valid!");
			groupNameField.clear();
		} else if (groupNameAlreadyPresent(name)) {
			setErrorMessageLabelSize(30);
			errorMessageLabel.setText("Name does already exist! Proceed anyways?");
			setProcessPaneSize(30);
			createButton.setDisable(true);
			cancelButton.setDisable(true);
		} else {
			createGroup(name);
			eventBus.dispatch(new BackEvent());
			// Restoring the original design as tabs will always be reused
			setErrorMessageLabelSize(0);
			groupNameField.clear();
			quickSelectList.getItems().forEach(q -> userList.getItems().add(q.getUser()));
			quickSelectList.getItems().clear();
			resizeQuickSelectSpace(0);
		}
	}

	/**
	 * 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) {
		Context.getInstance()
			.getClient()
			.send(new GroupCreation(name, quickSelectList.getItems().stream().map(q -> q.getUser().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);
	}

	/**
	 * Removes an element from the quickSelectList.
	 * 
	 * @param element the element to be removed.
	 * @since Envoy Client v0.3-beta
	 */
	public void removeFromQuickSelection(QuickSelectControl element) {
		quickSelectList.getItems().remove(element);
		userList.getItems().add(element.getUser());
		if (quickSelectList.getItems().isEmpty()) {
			resizeQuickSelectSpace(0);
			createButton.setDisable(true);
		}
	}

	private void resizeQuickSelectSpace(int value) {
		quickSelectList.setPrefHeight(value);
		quickSelectList.setMaxHeight(value);
		quickSelectList.setMinHeight(value);
	}

	@FXML
	private void backButtonClicked() {
		eventBus.dispatch(new BackEvent());
		setErrorMessageLabelSize(0);
		setProcessPaneSize(0);
	}

	@FXML
	private void proceedOnNameDuplication() {
		createButton.setDisable(false);
		cancelButton.setDisable(false);
		createGroup(name);
		eventBus.dispatch(new BackEvent());
		setErrorMessageLabelSize(0);
		setProcessPaneSize(0);
		groupNameField.clear();
	}

	@FXML
	private void cancelOnNameDuplication() {
		createButton.setDisable(false);
		cancelButton.setDisable(false);
		setErrorMessageLabelSize(0);
		setProcessPaneSize(0);
		groupNameField.clear();
	}

	private void setErrorMessageLabelSize(int value) {
		errorMessageLabel.setPrefHeight(value);
		errorMessageLabel.setMinHeight(value);
		errorMessageLabel.setMaxHeight(value);
	}

	private void setProcessPaneSize(int value) {
		proceedDuplicateButton.setPrefHeight(value);
		proceedDuplicateButton.setMinHeight(value);
		proceedDuplicateButton.setMaxHeight(value);
		cancelDuplicateButton.setPrefHeight(value);
		cancelDuplicateButton.setMinHeight(value);
		cancelDuplicateButton.setMaxHeight(value);
		errorProceedBox.setPrefHeight(value);
		errorProceedBox.setMinHeight(value);
		errorProceedBox.setMaxHeight(value);
	}

	@Event
	private void onContactOperation(ContactOperation operation) {
		if (operation.get() instanceof User) Platform.runLater(() -> {
			switch (operation.getOperationType()) {
				case ADD:
					userList.getItems().add((User) operation.get());
					break;
				case REMOVE:
					userList.getItems().removeIf(operation.get()::equals);
					break;
			}
		});
	}
}