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package net.java.html.boot.fx;

import java.net.URL;

import javafx.application.Platform;

import javafx.beans.value.ChangeListener;

import javafx.beans.value.ObservableValue;

import javafx.concurrent.Worker;

import javafx.scene.web.WebView;

import net.java.html.BrwsrCtx;

import net.java.html.boot.BrowserBuilder;

import net.java.html.js.JavaScriptBody;

import org.netbeans.html.boot.fx.AbstractFXPresenter;

/** Utility methods to use {@link WebView} and {@link JavaScriptBody} code

 * in existing <em>JavaFX</em> applications.

 * This class is for those who want to instantiate their own {@link WebView},

 * configure it manually, embed it into own <em>JavaFX</em>

 * application and based on other events in the application

 * {@link #runInBrowser(javafx.scene.web.WebView, java.lang.Runnable) re-execute code} 

 * inside of such {@link WebView}s.

 * In case such detailed control is not necessary,

 * consider using {@link BrowserBuilder}.

 * 

 * @author Jaroslav Tulach

 * @since 0.6

 */

public final class FXBrowsers {

    private FXBrowsers() {

    }

    /** Enables the Java/JavaScript bridge (that supports {@link JavaScriptBody} and co.)

     * in the provided <code>webView</code>. This method returns 

     * immediately. Once the support is active, it calls back specified

     * method in <code>onPageLoad</code> class - the class can possibly be

     * loaded by a different classloader (to enable replacement of

     * methods with {@link JavaScriptBody} annotations with executable

     * versions). The method <code>methodName</code> needs to be <code>public</code>

     * (in a public class), <code>static</code> and take either no parameters

     * or an array of {@link String}s.

     * <p>

     * This method sets {@link WebView#getUserData()} and {@link #runInBrowser(javafx.scene.web.WebView, java.lang.Runnable)}

     * relies on the value. Please don't alter it.

     * 

     * @param webView the instance of Web View to tweak

     * @param url the URL of the HTML page to load into the view

     * @param onPageLoad callback class with method <code>methodName</code>

     * @param methodName the method to call when the page is loaded

     * @param args arguments to pass to the <code>methodName</code> method

     */

    public static void load(

        final WebView webView, final URL url, 

        Class<?> onPageLoad, String methodName,

        String... args

    ) {

        BrowserBuilder.newBrowser(new Load(webView)).

            loadPage(url.toExternalForm()).

            loadClass(onPageLoad).

            invoke(methodName, args).

            showAndWait();

    }

    /** Enables the Java/JavaScript bridge (that supports {@link JavaScriptBody} and co.)

     * in the provided <code>webView</code>. This method returns 

     * immediately. Once the support is active, it calls back specified

     * method in <code>onPageLoad</code>'s run method. 

     * This is more convenient way to initialize the webview, 

     * but it requires one to make sure

     * all {@link JavaScriptBody} methods has been post-processed during

     * compilation and there will be no need to instantiate new classloader.

     * <p>

     * This method sets {@link WebView#getUserData()} and {@link #runInBrowser(javafx.scene.web.WebView, java.lang.Runnable)}

     * relies on the value. Please don't alter it.

     * 

     * @param webView the instance of Web View to tweak

     * @param url the URL of the HTML page to load into the view

     * @param onPageLoad callback to call when the page is ready

     * @since 0.8.1

     */

    public static void load(

        WebView webView, final URL url, Runnable onPageLoad

    ) {

        load(webView, url, onPageLoad, null);

    }

    /** Enables the Java/JavaScript bridge (that supports {@link JavaScriptBody} and co.)

     * in the provided <code>webView</code>. This method returns 

     * immediately. Once the support is active, it calls back specified

     * method in <code>onPageLoad</code>'s run method. 

     * This is more convenient way to initialize the webview, 

     * but it requires one to make sure

     * all {@link JavaScriptBody} methods has been post-processed during

     * compilation and there will be no need to instantiate new classloader.

     * <p>

     * This method sets {@link WebView#getUserData()} and {@link #runInBrowser(javafx.scene.web.WebView, java.lang.Runnable)}

     * relies on the value. Please don't alter it.

     * 

     * @param webView the instance of Web View to tweak

     * @param url the URL of the HTML page to load into the view

     * @param onPageLoad callback to call when the page is ready

     * @param loader the loader to use when constructing initial {@link BrwsrCtx} or <code>null</code>

     * @since 0.9

     */

    public static void load(

        WebView webView, final URL url, Runnable onPageLoad, ClassLoader loader

    ) {

        BrowserBuilder.newBrowser(new Load(webView)).

                loadPage(url.toExternalForm()).

                loadFinished(onPageLoad).

                classloader(loader).

                showAndWait();

    }

    /** Executes a code inside of provided {@link WebView}. This method

     * associates the {@link BrwsrCtx execution context} with provided browser,

     * so the {@link JavaScriptBody} annotations know where to execute

     * their JavaScript bodies.

     * The code is going to be executed synchronously

     * in case {@link Platform#isFxApplicationThread()} returns <code>true</code>.

     * Otherwise this method returns immediately and the code is executed

     * later via {@link Platform#runLater(java.lang.Runnable)}.

     * <p>

     * This method relies on {@link WebView#getUserData()} being properly

     * provided by the <code>load</code> methods in this class.

     * 

     * @param webView the web view previously prepared by one of the <code>load</code>

     *   methods in this class

     * @param code the code to execute

     * @throws IllegalArgumentException if the web view was not properly

     *   initialized

     * @see BrwsrCtx#execute(java.lang.Runnable) 

     * @since 0.8.1

     */

    public static void runInBrowser(WebView webView, Runnable code) {

        Object ud = webView.getUserData();

        if (!(ud instanceof Load)) {

            throw new IllegalArgumentException();

        }

        ((Load)ud).execute(code);

    }

    private static class Load extends AbstractFXPresenter {

        private final WebView webView;

        public Load(WebView webView) {

            webView.setUserData(this);

            this.webView = webView;

        }

        @Override

        protected void waitFinished() {

            // don't wait

        }

        @Override

        protected WebView findView(final URL resource) {

            final Worker<Void> w = webView.getEngine().getLoadWorker();

            w.stateProperty().addListener(new ChangeListener<Worker.State>() {

                private String previous;

                @Override

                public void changed(ObservableValue<? extends Worker.State> ov, Worker.State t, Worker.State newState) {

                    if (newState.equals(Worker.State.SUCCEEDED)) {

                        if (checkValid()) {

                            onPageLoad();

                        }

                    }

                    if (newState.equals(Worker.State.FAILED)) {

                        checkValid();

                        throw new IllegalStateException("Failed to load " + resource);

                    }

                }

                private boolean checkValid() {

                    final String crnt = webView.getEngine().getLocation();

                    if (previous != null && !previous.equals(crnt)) {

                        w.stateProperty().removeListener(this);

                        return false;

                    }

                    previous = crnt;

                    return true;

                }

            });

            return webView;

        }

    }

}