/*
 * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.servicetag;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.io.IOException;
import java.net.URI;

/**
 * BrowserSupport class.
 *
 * The implementation of the com.sun.servicetag API needs to be
 * compiled with JDK 5 as well since the consumer of this API
 * may require to support JDK 5 (e.g. NetBeans).
 *
 * The Desktop.browse() method can be backported in this class
 * if needed.  The current implementation only supports JDK 6.
 */
class BrowserSupport {
    private static boolean isBrowseSupported = false;
    private static Method browseMethod = null;
    private static Object desktop = null;
    private static volatile Boolean result = false;


    private static void initX() {
        if  (desktop != null) {
            return;
        }
        boolean supported = false;
        Method browseM = null;
        Object desktopObj = null;
        try {
            // Determine if java.awt.Desktop is supported
            Class<?> desktopCls = Class.forName("java.awt.Desktop", true, null);
            Method getDesktopM = desktopCls.getMethod("getDesktop");
            browseM = desktopCls.getMethod("browse", URI.class);

            Class<?> actionCls = Class.forName("java.awt.Desktop$Action", true, null);
            final Method isDesktopSupportedMethod = desktopCls.getMethod("isDesktopSupported");
            Method isSupportedMethod = desktopCls.getMethod("isSupported", actionCls);
            Field browseField = actionCls.getField("BROWSE");
            // isDesktopSupported calls getDefaultToolkit which can block
            // infinitely, see 6636099 for details, to workaround we call
            // in a  thread and time it out, noting that the issue is specific
            // to X11, it does not hurt for Windows.
            Thread xthread = new Thread() {
                public void run() {
                    try {
                        // support only if Desktop.isDesktopSupported() and
                        // Desktop.isSupported(Desktop.Action.BROWSE) return true.
                        result = (Boolean) isDesktopSupportedMethod.invoke(null);
                    } catch (IllegalAccessException e) {
                        // should never reach here
                        throw new InternalError("Desktop.getDesktop() method not found", e);
                    } catch (InvocationTargetException e) {
                        // browser not supported
                        if (Util.isVerbose()) {
                            e.printStackTrace();
                        }
                    }
                }
            };
            // set it to daemon, so that the vm will exit.
            xthread.setDaemon(true);
            xthread.start();
            try {
                xthread.join(5 * 1000);
            } catch (InterruptedException ie) {
                // ignore the exception
            }
            if (result.booleanValue()) {
                desktopObj = getDesktopM.invoke(null);
                result = (Boolean) isSupportedMethod.invoke(desktopObj, browseField.get(null));
                supported = result.booleanValue();
            }
        } catch (IllegalAccessException e) {
            // should never reach here
            throw new InternalError("Desktop.getDesktop() method not found", e);
        } catch (ReflectiveOperationException e) {
            // browser not supported
            if (Util.isVerbose()) {
                e.printStackTrace();
            }
        }
        isBrowseSupported = supported;
        browseMethod = browseM;
        desktop = desktopObj;
    }

    static boolean isSupported() {
        initX();
        return isBrowseSupported;
    }

    /**
     * Launches the default browser to display a {@code URI}.
     * If the default browser is not able to handle the specified
     * {@code URI}, the application registered for handling
     * {@code URIs} of the specified type is invoked. The application
     * is determined from the protocol and path of the {@code URI}, as
     * defined by the {@code URI} class.
     * <p>
     * This method calls the Desktop.getDesktop().browse() method.
     * <p>
     * @param uri the URI to be displayed in the user default browser
     *
     * @throws NullPointerException if {@code uri} is {@code null}
     * @throws UnsupportedOperationException if the current platform
     * does not support the {@link Desktop.Action#BROWSE} action
     * @throws IOException if the user default browser is not found,
     * or it fails to be launched, or the default handler application
     * failed to be launched
     * @throws IllegalArgumentException if the necessary permissions
     * are not available and the URI can not be converted to a {@code URL}
     */
    static void browse(URI uri) throws IOException {
        if (uri == null) {
            throw new NullPointerException("null uri");
        }
        if (!isSupported()) {
            throw new UnsupportedOperationException("Browse operation is not supported");
        }

        // Call Desktop.browse() method
        try {
            if (Util.isVerbose()) {
                System.out.println("desktop: " + desktop + ":browsing..." + uri);
            }
            browseMethod.invoke(desktop, uri);
        } catch (IllegalAccessException e) {
            // should never reach here
            throw new InternalError("Desktop.getDesktop() method not found", e);
        } catch (InvocationTargetException e) {
            Throwable x = e.getCause();
            if (x != null) {
                if (x instanceof UnsupportedOperationException) {
                    throw (UnsupportedOperationException) x;
                } else if (x instanceof IllegalArgumentException) {
                    throw (IllegalArgumentException) x;
                } else if (x instanceof IOException) {
                    throw (IOException) x;
                } else if (x instanceof SecurityException) {
                    throw (SecurityException) x;
                } else {
                    // ignore
                }
            }
        }
    }
}