//
//  ========================================================================
//  Copyright (c) 1995-2019 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.olamy;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyUpEvent;
import com.google.gwt.event.dom.client.KeyUpHandler;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.DialogBox;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;

/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class App implements EntryPoint
{
    /**
     * The message displayed to the user when the server cannot be reached or
     * returns an error.
     */
    private static final String SERVER_ERROR = "An error occurred while "
        + "attempting to contact the server. Please check your network "
        + "connection and try again.";

    /**
     * Create a remote service proxy to talk to the server-side Greeting service.
     */
    private final GreetingServiceAsync greetingService = GWT
        .create(GreetingService.class);

    /**
     * This is the entry point method.
     */
    public void onModuleLoad()
    {
        final Button sendButton = new Button("Send");
        final TextBox nameField = new TextBox();
        nameField.setText("GWT User");
        final Label errorLabel = new Label();

        // We can add style names to widgets
        sendButton.addStyleName("sendButton");

        // Add the nameField and sendButton to the RootPanel
        // Use RootPanel.get() to get the entire body element
        RootPanel.get("nameFieldContainer").add(nameField);
        RootPanel.get("sendButtonContainer").add(sendButton);
        RootPanel.get("errorLabelContainer").add(errorLabel);

        // Focus the cursor on the name field when the app loads
        nameField.setFocus(true);
        nameField.selectAll();

        // Create the popup dialog box
        final DialogBox dialogBox = new DialogBox();
        dialogBox.setText("Remote Procedure Call");
        dialogBox.setAnimationEnabled(true);
        final Button closeButton = new Button("Close");
        // We can set the id of a widget by accessing its Element
        closeButton.getElement().setId("closeButton");
        final Label textToServerLabel = new Label();
        final HTML serverResponseLabel = new HTML();
        VerticalPanel dialogVPanel = new VerticalPanel();
        dialogVPanel.addStyleName("dialogVPanel");
        dialogVPanel.add(new HTML("<b>Sending name to the server:</b>"));
        dialogVPanel.add(textToServerLabel);
        dialogVPanel.add(new HTML("<br><b>Server replies:</b>"));
        dialogVPanel.add(serverResponseLabel);
        dialogVPanel.setHorizontalAlignment(VerticalPanel.ALIGN_RIGHT);
        dialogVPanel.add(closeButton);
        dialogBox.setWidget(dialogVPanel);

        // Add a handler to close the DialogBox
        closeButton.addClickHandler(new ClickHandler()
        {
            public void onClick(ClickEvent event)
            {
                dialogBox.hide();
                sendButton.setEnabled(true);
                sendButton.setFocus(true);
            }
        });

        // Create a handler for the sendButton and nameField
        class MyHandler implements ClickHandler, KeyUpHandler
        {
            /**
             * Fired when the user clicks on the sendButton.
             */
            public void onClick(ClickEvent event)
            {
                sendNameToServer();
            }

            /**
             * Fired when the user types in the nameField.
             */
            public void onKeyUp(KeyUpEvent event)
            {
                if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER)
                {
                    sendNameToServer();
                }
            }

            /**
             * Send the name from the nameField to the server and wait for a response.
             */
            private void sendNameToServer()
            {
                // First, we validate the input.
                errorLabel.setText("");
                String textToServer = nameField.getText();
                if (!FieldVerifier.isValidName(textToServer))
                {
                    errorLabel.setText("Please enter at least four characters");
                    return;
                }

                // Then, we send the input to the server.
                sendButton.setEnabled(false);
                textToServerLabel.setText(textToServer);
                serverResponseLabel.setText("");
                greetingService.greetServer(textToServer,
                    new AsyncCallback<GreetingResponse>()
                    {
                        public void onFailure(Throwable caught)
                        {
                            // Show the RPC error message to the user
                            dialogBox
                                .setText("Remote Procedure Call - Failure");
                            serverResponseLabel
                                .addStyleName("serverResponseLabelError");
                            serverResponseLabel.setHTML(SERVER_ERROR);
                            dialogBox.center();
                            closeButton.setFocus(true);
                        }

                        public void onSuccess(GreetingResponse result)
                        {
                            dialogBox.setText("Remote Procedure Call");
                            serverResponseLabel
                                .removeStyleName("serverResponseLabelError");
                            serverResponseLabel.setHTML(new SafeHtmlBuilder()
                                .appendEscaped(result.getGreeting())
                                .appendHtmlConstant("<br><br>I am running ")
                                .appendEscaped(result.getServerInfo())
                                .appendHtmlConstant(".<br><br>It looks like you are using:<br>")
                                .appendEscaped(result.getUserAgent())
                                .toSafeHtml());
                            dialogBox.center();
                            closeButton.setFocus(true);
                        }
                    });
            }
        }

        // Add a handler to send the name to the server
        MyHandler handler = new MyHandler();
        sendButton.addClickHandler(handler);
        nameField.addKeyUpHandler(handler);
    }
}
