/**

 * Back 2 Browser Bytecode Translator

 * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, version 2 of the License.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. Look for COPYING file in the top folder.

 * If not, see http://opensource.org/licenses/GPL-2.0.

 */

package org.apidesign.bck2brwsr.launcher;

import java.io.Closeable;

import java.io.File;

import java.io.IOException;

import java.lang.reflect.Constructor;

/** An abstraction for executing tests in a Bck2Brwsr virtual machine.

 * Either in {@link Launcher#createJavaScript JavaScript engine}, 

 * or in {@link Launcher#createBrowser external browser}.

 * <p>

 * There also are methods to {@link #showDir(java.io.File, java.lang.String) display pages} 

 * in an external browser served by internal HTTP server.

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

public abstract class Launcher {

    Launcher() {

    }

    /** Initializes the launcher. This may mean starting a web browser or

     * initializing execution engine.

     * @throws IOException if something goes wrong

     */

    public abstract void initialize() throws IOException;

    /** Shuts down the launcher.

     * @throws IOException if something goes wrong

     */

    public abstract void shutdown() throws IOException;

    /** Builds an invocation context. The context can later be customized

     * and {@link InvocationContext#invoke() invoked}.

     * 

     * @param clazz the class to execute method from

     * @param method the method to execute

     * @return the context pointing to the selected method

     */

    public InvocationContext createInvocation(Class<?> clazz, String method) {

        return new InvocationContext(this, clazz, method);

    }

    /** Creates launcher that uses internal JavaScript engine (Rhino).

     * @return the launcher

     */

    public static Launcher createJavaScript() {

        try {

            Class<?> c = loadClass("org.apidesign.bck2brwsr.launcher.JSLauncher");

            return (Launcher) c.newInstance();

        } catch (Exception ex) {

            throw new IllegalStateException("Please include org.apidesign.bck2brwsr:launcher.html dependency!", ex);

        }

    }

    /** Creates launcher that is using external browser.

     * 

     * @param cmd <code>null</code> to use <code>java.awt.Desktop</code> to show the launcher

     *    or a string to execute in an external process (with a parameter to the URL)

     * @return launcher executing in external browser.

     */

    public static Launcher createBrowser(String cmd) {

        String msg = "Trying to create browser '" + cmd + "'";

        try {

            Class<?> c;

            if ("fx".equals(cmd)) { // NOI18N

                msg = "Please include org.apidesign.bck2brwsr:launcher.fx dependency!";

                c = loadClass("org.apidesign.bck2brwsr.launcher.FXBrwsrLauncher"); // NOI18N

            } else {

                msg = "Please include org.apidesign.bck2brwsr:launcher.html dependency!";

                c = loadClass("org.apidesign.bck2brwsr.launcher.Bck2BrwsrLauncher"); // NOI18N

            }

            Constructor<?> cnstr = c.getConstructor(String.class);

            return (Launcher) cnstr.newInstance(cmd);

        } catch (Exception ex) {

            throw new IllegalStateException(msg, ex);

        }

    }

    /** Starts an HTTP server which provides access to classes and resources

     * available in the <code>classes</code> URL and shows a start page

     * available as {@link ClassLoader#getResource(java.lang.String)} from the

     * provide classloader. Opens a browser with URL showing the start page.

     * 

     * @param classes classloader offering access to classes and resources

     * @param startpage page to show in the browser

     * @return interface that allows one to stop the server

     * @throws IOException if something goes wrong

     */

    public static Closeable showURL(ClassLoader classes, String startpage) throws IOException {

        Launcher l = createBrowser(null);

        l.addClassLoader(classes);

        l.showURL(startpage);

        return (Closeable) l;

    }

    /** Starts an HTTP server which provides access to certain directory.

     * The <code>startpage</code> should be relative location inside the root 

     * directory. Opens a browser with URL showing the start page.

     * 

     * @param directory the root directory on disk

     * @param startpage relative path from the root to the page

     * @exception IOException if something goes wrong.

     */

    public static Closeable showDir(File directory, String startpage) throws IOException {

        Launcher l = createBrowser(null);

        l.showDirectory(directory, startpage);

        return (Closeable) l;

    }

    abstract InvocationContext runMethod(InvocationContext c) throws IOException; 

    private static Class<?> loadClass(String cn) throws ClassNotFoundException {

        return Launcher.class.getClassLoader().loadClass(cn);

    }

    void showDirectory(File directory, String startpage) throws IOException {

        throw new UnsupportedOperationException();

    }

    void showURL(String startpage) throws IOException {

        throw new UnsupportedOperationException();

    }

    void addClassLoader(ClassLoader classes) {

        throw new UnsupportedOperationException();

    }

}