/*

 * Copyright (c) 2005, 2006, 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

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 */

package java.awt;

import java.io.File;

import java.io.IOException;

import java.net.URISyntaxException;

import java.net.URI;

import java.net.URL;

import java.net.MalformedURLException;

import java.awt.AWTPermission;

import java.awt.GraphicsEnvironment;

import java.awt.HeadlessException;

import java.awt.peer.DesktopPeer;

import sun.awt.SunToolkit;

import sun.awt.HeadlessToolkit;

import java.io.FilePermission;

import sun.security.util.SecurityConstants;

/**

 * The {@code Desktop} class allows a Java application to launch

 * associated applications registered on the native desktop to handle

 * a {@link java.net.URI} or a file.

 *

 * <p> Supported operations include:

 * <ul>

 *   <li>launching the user-default browser to show a specified

 *       URI;</li>

 *   <li>launching the user-default mail client with an optional

 *       {@code mailto} URI;</li>

 *   <li>launching a registered application to open, edit or print a

 *       specified file.</li>

 * </ul>

 *

 * <p> This class provides methods corresponding to these

 * operations. The methods look for the associated application

 * registered on the current platform, and launch it to handle a URI

 * or file. If there is no associated application or the associated

 * application fails to be launched, an exception is thrown.

 *

 * <p> An application is registered to a URI or file type; for

 * example, the {@code "sxi"} file extension is typically registered

 * to StarOffice.  The mechanism of registering, accessing, and

 * launching the associated application is platform-dependent.

 *

 * <p> Each operation is an action type represented by the {@link

 * Desktop.Action} class.

 *

 * <p> Note: when some action is invoked and the associated

 * application is executed, it will be executed on the same system as

 * the one on which the Java application was launched.

 *

 * @since 1.6

 * @author Armin Chen

 * @author George Zhang

 */

public class Desktop {

    /**

     * Represents an action type.  Each platform supports a different

     * set of actions.  You may use the {@link Desktop#isSupported}

     * method to determine if the given action is supported by the

     * current platform.

     * @see java.awt.Desktop#isSupported(java.awt.Desktop.Action)

     * @since 1.6

     */

    public static enum Action {

        /**

         * Represents an "open" action.

         * @see Desktop#open(java.io.File)

         */

        OPEN,

        /**

         * Represents an "edit" action.

         * @see Desktop#edit(java.io.File)

         */

        EDIT,

        /**

         * Represents a "print" action.

         * @see Desktop#print(java.io.File)

         */

        PRINT,

        /**

         * Represents a "mail" action.

         * @see Desktop#mail()

         * @see Desktop#mail(java.net.URI)

         */

        MAIL,

        /**

         * Represents a "browse" action.

         * @see Desktop#browse(java.net.URI)

         */

        BROWSE

    };

    private DesktopPeer peer;

    /**

     * Suppresses default constructor for noninstantiability.

     */

    private Desktop() {

        peer = Toolkit.getDefaultToolkit().createDesktopPeer(this);

    }

    /**

     * Returns the <code>Desktop</code> instance of the current

     * browser context.  On some platforms the Desktop API may not be

     * supported; use the {@link #isDesktopSupported} method to

     * determine if the current desktop is supported.

     * @return the Desktop instance of the current browser context

     * @throws HeadlessException if {@link

     * GraphicsEnvironment#isHeadless()} returns {@code true}

     * @throws UnsupportedOperationException if this class is not

     * supported on the current platform

     * @see #isDesktopSupported()

     * @see java.awt.GraphicsEnvironment#isHeadless

     */

    public static synchronized Desktop getDesktop(){

        if (GraphicsEnvironment.isHeadless()) throw new HeadlessException();

        if (!Desktop.isDesktopSupported()) {

            throw new UnsupportedOperationException("Desktop API is not " +

                                                    "supported on the current platform");

        }

        sun.awt.AppContext context = sun.awt.AppContext.getAppContext();

        Desktop desktop = (Desktop)context.get(Desktop.class);

        if (desktop == null) {

            desktop = new Desktop();

            context.put(Desktop.class, desktop);

        }

        return desktop;

    }

    /**

     * Tests whether this class is supported on the current platform.

     * If it's supported, use {@link #getDesktop()} to retrieve an

     * instance.

     *

     * @return <code>true</code> if this class is supported on the

     *         current platform; <code>false</code> otherwise

     * @see #getDesktop()

     */

    public static boolean isDesktopSupported(){

        Toolkit defaultToolkit = Toolkit.getDefaultToolkit();

        if (defaultToolkit instanceof SunToolkit) {

            return ((SunToolkit)defaultToolkit).isDesktopSupported();

        }

        return false;

    }

    /**

     * Tests whether an action is supported on the current platform.

     *

     * <p>Even when the platform supports an action, a file or URI may

     * not have a registered application for the action.  For example,

     * most of the platforms support the {@link Desktop.Action#OPEN}

     * action.  But for a specific file, there may not be an

     * application registered to open it.  In this case, {@link

     * #isSupported} may return {@code true}, but the corresponding

     * action method will throw an {@link IOException}.

     *

     * @param action the specified {@link Action}

     * @return <code>true</code> if the specified action is supported on

     *         the current platform; <code>false</code> otherwise

     * @see Desktop.Action

     */

    public boolean isSupported(Action action) {

        return peer.isSupported(action);

    }

    /**

     * Checks if the file is a valid file and readable.

     *

     * @throws SecurityException If a security manager exists and its

     *         {@link SecurityManager#checkRead(java.lang.String)} method

     *         denies read access to the file

     * @throws NullPointerException if file is null

     * @throws IllegalArgumentException if file doesn't exist

     */

    private static void checkFileValidation(File file){

        if (file == null) throw new NullPointerException("File must not be null");

        if (!file.exists()) {

            throw new IllegalArgumentException("The file: "

                                               + file.getPath() + " doesn't exist.");

        }

        file.canRead();

    }

    /**

     * Checks if the action type is supported.

     *

     * @param actionType the action type in question

     * @throws UnsupportedOperationException if the specified action type is not

     *         supported on the current platform

     */

    private void checkActionSupport(Action actionType){

        if (!isSupported(actionType)) {

            throw new UnsupportedOperationException("The " + actionType.name()

                                                    + " action is not supported on the current platform!");

        }

    }

    /**

     *  Calls to the security manager's <code>checkPermission</code> method with

     *  an <code>AWTPermission("showWindowWithoutWarningBanner")</code>

     *  permission.

     */

    private void checkAWTPermission(){

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new AWTPermission(

                                   "showWindowWithoutWarningBanner"));

        }

    }

    /**

     * Launches the associated application to open the file.

     *

     * <p> If the specified file is a directory, the file manager of

     * the current platform is launched to open it.

     *

     * @param file the file to be opened with the associated application

     * @throws NullPointerException if {@code file} is {@code null}

     * @throws IllegalArgumentException if the specified file doesn't

     * exist

     * @throws UnsupportedOperationException if the current platform

     * does not support the {@link Desktop.Action#OPEN} action

     * @throws IOException if the specified file has no associated

     * application or the associated application fails to be launched

     * @throws SecurityException if a security manager exists and its

     * {@link java.lang.SecurityManager#checkRead(java.lang.String)}

     * method denies read access to the file, or it denies the

     * <code>AWTPermission("showWindowWithoutWarningBanner")</code>

     * permission, or the calling thread is not allowed to create a

     * subprocess

     * @see java.awt.AWTPermission

     */

    public void open(File file) throws IOException {

        checkAWTPermission();

        checkExec();

        checkActionSupport(Action.OPEN);

        checkFileValidation(file);

        peer.open(file);

    }

    /**

     * Launches the associated editor application and opens a file for

     * editing.

     *

     * @param file the file to be opened for editing

     * @throws NullPointerException if the specified file is {@code null}

     * @throws IllegalArgumentException if the specified file doesn't

     * exist

     * @throws UnsupportedOperationException if the current platform

     * does not support the {@link Desktop.Action#EDIT} action

     * @throws IOException if the specified file has no associated

     * editor, or the associated application fails to be launched

     * @throws SecurityException if a security manager exists and its

     * {@link java.lang.SecurityManager#checkRead(java.lang.String)}

     * method denies read access to the file, or {@link

     * java.lang.SecurityManager#checkWrite(java.lang.String)} method

     * denies write access to the file, or it denies the

     * <code>AWTPermission("showWindowWithoutWarningBanner")</code>

     * permission, or the calling thread is not allowed to create a

     * subprocess

     * @see java.awt.AWTPermission

     */

    public void edit(File file) throws IOException {

        checkAWTPermission();

        checkExec();

        checkActionSupport(Action.EDIT);

        file.canWrite();

        checkFileValidation(file);

        peer.edit(file);

    }

    /**

     * Prints a file with the native desktop printing facility, using

     * the associated application's print command.

     *

     * @param file the file to be printed

     * @throws NullPointerException if the specified file is {@code

     * null}

     * @throws IllegalArgumentException if the specified file doesn't

     * exist

     * @throws UnsupportedOperationException if the current platform

     *         does not support the {@link Desktop.Action#PRINT} action

     * @throws IOException if the specified file has no associated

     * application that can be used to print it

     * @throws SecurityException if a security manager exists and its

     * {@link java.lang.SecurityManager#checkRead(java.lang.String)}

     * method denies read access to the file, or its {@link

     * java.lang.SecurityManager#checkPrintJobAccess()} method denies

     * the permission to print the file, or the calling thread is not

     * allowed to create a subprocess

     */

    public void print(File file) throws IOException {

        checkExec();

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPrintJobAccess();

        }

        checkActionSupport(Action.PRINT);

        checkFileValidation(file);

        peer.print(file);

    }

    /**

     * 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>

     * If the calling thread does not have the necessary permissions,

     * and this is invoked from within an applet,

     * {@code AppletContext.showDocument()} is used. Similarly, if the calling

     * does not have the necessary permissions, and this is invoked from within

     * a Java Web Started application, {@code BasicService.showDocument()}

     * is used.

     *

     * @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 SecurityException if a security manager exists and it

     * denies the

     * <code>AWTPermission("showWindowWithoutWarningBanner")</code>

     * permission, or the calling thread is not allowed to create a

     * subprocess; and not invoked from within an applet or Java Web Started

     * application

     * @throws IllegalArgumentException if the necessary permissions

     * are not available and the URI can not be converted to a {@code URL}

     * @see java.net.URI

     * @see java.awt.AWTPermission

     * @see java.applet.AppletContext

     */

    public void browse(URI uri) throws IOException {

        SecurityException securityException = null;

        try {

            checkAWTPermission();

            checkExec();

        } catch (SecurityException e) {

            securityException = e;

        }

        checkActionSupport(Action.BROWSE);

        if (uri == null) {

            throw new NullPointerException();

        }

        if (securityException == null) {

            peer.browse(uri);

            return;

        }

        // Delegate to DesktopBrowse so that it can work in

        // applet/webstart.

        URL url = null;

        try {

            url = uri.toURL();

        } catch (MalformedURLException e) {

            throw new IllegalArgumentException("Unable to convert URI to URL", e);

        }

        sun.awt.DesktopBrowse db = sun.awt.DesktopBrowse.getInstance();

        if (db == null) {

            // Not in webstart/applet, throw the exception.

            throw securityException;

        }

        db.browse(url);

    }

    /**

     * Launches the mail composing window of the user default mail

     * client.

     *

     * @throws UnsupportedOperationException if the current platform

     * does not support the {@link Desktop.Action#MAIL} action

     * @throws IOException if the user default mail client is not

     * found, or it fails to be launched

     * @throws SecurityException if a security manager exists and it

     * denies the

     * <code>AWTPermission("showWindowWithoutWarningBanner")</code>

     * permission, or the calling thread is not allowed to create a

     * subprocess

     * @see java.awt.AWTPermission

     */

    public void mail() throws IOException {

        checkAWTPermission();

        checkExec();

        checkActionSupport(Action.MAIL);

        URI mailtoURI = null;

        try{

            mailtoURI = new URI("mailto:?");

            peer.mail(mailtoURI);

        } catch (URISyntaxException e){

            // won't reach here.

        }

    }

    /**

     * Launches the mail composing window of the user default mail

     * client, filling the message fields specified by a {@code

     * mailto:} URI.

     *

     * <p> A <code>mailto:</code> URI can specify message fields

     * including <i>"to"</i>, <i>"cc"</i>, <i>"subject"</i>,

     * <i>"body"</i>, etc.  See <a

     * href="http://www.ietf.org/rfc/rfc2368.txt">The mailto URL

     * scheme (RFC 2368)</a> for the {@code mailto:} URI specification

     * details.

     *

     * @param mailtoURI the specified {@code mailto:} URI

     * @throws NullPointerException if the specified URI is {@code

     * null}

     * @throws IllegalArgumentException if the URI scheme is not

     *         <code>"mailto"</code>

     * @throws UnsupportedOperationException if the current platform

     * does not support the {@link Desktop.Action#MAIL} action

     * @throws IOException if the user default mail client is not

     * found or fails to be launched

     * @throws SecurityException if a security manager exists and it

     * denies the

     * <code>AWTPermission("showWindowWithoutWarningBanner")</code>

     * permission, or the calling thread is not allowed to create a

     * subprocess

     * @see java.net.URI

     * @see java.awt.AWTPermission

     */

    public  void mail(URI mailtoURI) throws IOException {

        checkAWTPermission();

        checkExec();

        checkActionSupport(Action.MAIL);

        if (mailtoURI == null) throw new NullPointerException();

        if (!"mailto".equalsIgnoreCase(mailtoURI.getScheme())) {

            throw new IllegalArgumentException("URI scheme is not \"mailto\"");

        }

        peer.mail(mailtoURI);

    }

    private void checkExec() throws SecurityException {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new FilePermission("<<ALL FILES>>",

                                                  SecurityConstants.FILE_EXECUTE_ACTION));

        }

    }

}