/*

 * Copyright 1996-2006 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.awt.datatransfer;

import java.awt.Toolkit;

import java.io.*;

import java.nio.*;

import java.util.*;

import sun.awt.datatransfer.DataTransferer;

/**

 * A {@code DataFlavor} provides meta information about data. {@code DataFlavor}

 * is typically used to access data on the clipboard, or during

 * a drag and drop operation.

 * <p>

 * An instance of {@code DataFlavor} encapsulates a content type as

 * defined in <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>

 * and <a href="http://www.ietf.org/rfc/rfc2046.txt">RFC 2046</a>.

 * A content type is typically referred to as a MIME type.

 * <p>

 * A content type consists of a media type (referred

 * to as the primary type), a subtype, and optional parameters. See

 * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>

 * for details on the syntax of a MIME type.

 * <p>

 * The JRE data transfer implementation interprets the parameter "class"

 * of a MIME type as <B>a representation class</b>.

 * The representation class reflects the class of the object being

 * transferred. In other words, the representation class is the type of

 * object returned by {@link Transferable#getTransferData}.

 * For example, the MIME type of {@link #imageFlavor} is

 * {@code "image/x-java-image;class=java.awt.Image"},

 * the primary type is {@code image}, the subtype is

 * {@code x-java-image}, and the representation class is

 * {@code java.awt.Image}. When {@code getTransferData} is invoked

 * with a {@code DataFlavor} of {@code imageFlavor}, an instance of

 * {@code java.awt.Image} is returned.

 * It's important to note that {@code DataFlavor} does no error checking

 * against the representation class. It is up to consumers of

 * {@code DataFlavor}, such as {@code Transferable}, to honor the representation

 * class.

 * <br>

 * Note, if you do not specify a representation class when

 * creating a {@code DataFlavor}, the default

 * representation class is used. See appropriate documentation for

 * {@code DataFlavor}'s constructors.

 * <p>

 * Also, {@code DataFlavor} instances with the "text" primary

 * MIME type may have a "charset" parameter. Refer to

 * <a href="http://www.ietf.org/rfc/rfc2046.txt">RFC 2046</a> and

 * {@link #selectBestTextFlavor} for details on "text" MIME types

 * and the "charset" parameter.

 * <p>

 * Equality of {@code DataFlavors} is determined by the primary type,

 * subtype, and representation class. Refer to {@link #equals(DataFlavor)} for

 * details. When determining equality, any optional parameters are ignored.

 * For example, the following produces two {@code DataFlavors} that

 * are considered identical:

 * <pre>

 *   DataFlavor flavor1 = new DataFlavor(Object.class, "X-test/test; class=<java.lang.Object>; foo=bar");

 *   DataFlavor flavor2 = new DataFlavor(Object.class, "X-test/test; class=<java.lang.Object>; x=y");

 *   // The following returns true.

 *   flavor1.equals(flavor2);

 * </pre>

 * As mentioned, {@code flavor1} and {@code flavor2} are considered identical.

 * As such, asking a {@code Transferable} for either {@code DataFlavor} returns

 * the same results.

 * <p>

 * For more information on the using data transfer with Swing see

 * the <a href="http://java.sun.com/docs/books/tutorial/uiswing/misc/dnd.html">

 * How to Use Drag and Drop and Data Transfer</a>,

 * section in <em>Java Tutorial</em>.

 *

 * @author      Blake Sullivan

 * @author      Laurence P. G. Cable

 * @author      Jeff Dunn

 */

public class DataFlavor implements Externalizable, Cloneable {

    private static final long serialVersionUID = 8367026044764648243L;

    private static final Class ioInputStreamClass = java.io.InputStream.class;

    /**

     * Tries to load a class from: the bootstrap loader, the system loader,

     * the context loader (if one is present) and finally the loader specified.

     *

     * @param className the name of the class to be loaded

     * @param fallback the fallback loader

     * @return the class loaded

     * @exception ClassNotFoundException if class is not found

     */

    protected final static Class<?> tryToLoadClass(String className,

                                                   ClassLoader fallback)

        throws ClassNotFoundException

    {

        ClassLoader systemClassLoader = (ClassLoader)

            java.security.AccessController.doPrivileged(

                new java.security.PrivilegedAction() {

                    public Object run() {

                        ClassLoader cl = Thread.currentThread().

                            getContextClassLoader();

                        return (cl != null)

                            ? cl

                            : ClassLoader.getSystemClassLoader();

                    }

                    });

        try {

            return Class.forName(className, true, systemClassLoader);

        } catch (ClassNotFoundException e2) {

            if (fallback != null) {

                return Class.forName(className, true, fallback);

            } else {

                throw new ClassNotFoundException(className);

            }

        }

    }

    /*

     * private initializer

     */

    static private DataFlavor createConstant(Class rc, String prn) {

        try {

            return new DataFlavor(rc, prn);

        } catch (Exception e) {

            return null;

        }

    }

    /*

     * private initializer

     */

    static private DataFlavor createConstant(String mt, String prn) {

        try {

            return new DataFlavor(mt, prn);

        } catch (Exception e) {

            return null;

        }

    }

    /**

     * The <code>DataFlavor</code> representing a Java Unicode String class,

     * where:

     * <pre>

     *     representationClass = java.lang.String

     *     mimeType           = "application/x-java-serialized-object"

     * </pre>

     */

    public static final DataFlavor stringFlavor = createConstant(java.lang.String.class, "Unicode String");

    /**

     * The <code>DataFlavor</code> representing a Java Image class,

     * where:

     * <pre>

     *     representationClass = java.awt.Image

     *     mimeType            = "image/x-java-image"

     * </pre>

     */

    public static final DataFlavor imageFlavor = createConstant("image/x-java-image; class=java.awt.Image", "Image");

    /**

     * The <code>DataFlavor</code> representing plain text with Unicode

     * encoding, where:

     * <pre>

     *     representationClass = InputStream

     *     mimeType            = "text/plain; charset=unicode"

     * </pre>

     * This <code>DataFlavor</code> has been <b>deprecated</b> because

     * (1) Its representation is an InputStream, an 8-bit based representation,

     * while Unicode is a 16-bit character set; and (2) The charset "unicode"

     * is not well-defined. "unicode" implies a particular platform's

     * implementation of Unicode, not a cross-platform implementation.

     *

     * @deprecated as of 1.3. Use <code>DataFlavor.getReaderForText(Transferable)</code>

     *             instead of <code>Transferable.getTransferData(DataFlavor.plainTextFlavor)</code>.

     */

    @Deprecated

    public static final DataFlavor plainTextFlavor = createConstant("text/plain; charset=unicode; class=java.io.InputStream", "Plain Text");

    /**

     * A MIME Content-Type of application/x-java-serialized-object represents

     * a graph of Java object(s) that have been made persistent.

     *

     * The representation class associated with this <code>DataFlavor</code>

     * identifies the Java type of an object returned as a reference

     * from an invocation <code>java.awt.datatransfer.getTransferData</code>.

     */

    public static final String javaSerializedObjectMimeType = "application/x-java-serialized-object";

    /**

     * To transfer a list of files to/from Java (and the underlying

     * platform) a <code>DataFlavor</code> of this type/subtype and

     * representation class of <code>java.util.List</code> is used.

     * Each element of the list is required/guaranteed to be of type

     * <code>java.io.File</code>.

     */

    public static final DataFlavor javaFileListFlavor = createConstant("application/x-java-file-list;class=java.util.List", null);

    /**

     * To transfer a reference to an arbitrary Java object reference that

     * has no associated MIME Content-type, across a <code>Transferable</code>

     * interface WITHIN THE SAME JVM, a <code>DataFlavor</code>

     * with this type/subtype is used, with a <code>representationClass</code>

     * equal to the type of the class/interface being passed across the

     * <code>Transferable</code>.

     * <p>

     * The object reference returned from

     * <code>Transferable.getTransferData</code> for a <code>DataFlavor</code>

     * with this MIME Content-Type is required to be

     * an instance of the representation Class of the <code>DataFlavor</code>.

     */

    public static final String javaJVMLocalObjectMimeType = "application/x-java-jvm-local-objectref";

    /**

     * In order to pass a live link to a Remote object via a Drag and Drop

     * <code>ACTION_LINK</code> operation a Mime Content Type of

     * application/x-java-remote-object should be used,

     * where the representation class of the <code>DataFlavor</code>

     * represents the type of the <code>Remote</code> interface to be

     * transferred.

     */

    public static final String javaRemoteObjectMimeType = "application/x-java-remote-object";

    /**

     * Constructs a new <code>DataFlavor</code>.  This constructor is

     * provided only for the purpose of supporting the

     * <code>Externalizable</code> interface.  It is not

     * intended for public (client) use.

     *

     * @since 1.2

     */

    public DataFlavor() {

        super();

    }

    /**

     * Constructs a fully specified <code>DataFlavor</code>.

     *

     * @exception NullPointerException if either <code>primaryType</code>,

     *            <code>subType</code> or <code>representationClass</code> is null

     */

    private DataFlavor(String primaryType, String subType, MimeTypeParameterList params, Class representationClass, String humanPresentableName) {

        super();

        if (primaryType == null) {

            throw new NullPointerException("primaryType");

        }

        if (subType == null) {

            throw new NullPointerException("subType");

        }

        if (representationClass == null) {

            throw new NullPointerException("representationClass");

        }

        if (params == null) params = new MimeTypeParameterList();

        params.set("class", representationClass.getName());

        if (humanPresentableName == null) {

            humanPresentableName = (String)params.get("humanPresentableName");

            if (humanPresentableName == null)

                humanPresentableName = primaryType + "/" + subType;

        }

        try {

            mimeType = new MimeType(primaryType, subType, params);

        } catch (MimeTypeParseException mtpe) {

            throw new IllegalArgumentException("MimeType Parse Exception: " + mtpe.getMessage());

        }

        this.representationClass  = representationClass;

        this.humanPresentableName = humanPresentableName;

        mimeType.removeParameter("humanPresentableName");

    }

    /**

     * Constructs a <code>DataFlavor</code> that represents a Java class.

     * <p>

     * The returned <code>DataFlavor</code> will have the following

     * characteristics:

     * <pre>

     *    representationClass = representationClass

     *    mimeType            = application/x-java-serialized-object

     * </pre>

     * @param representationClass the class used to transfer data in this flavor

     * @param humanPresentableName the human-readable string used to identify

     *                 this flavor; if this parameter is <code>null</code>

     *                 then the value of the the MIME Content Type is used

     * @exception NullPointerException if <code>representationClass</code> is null

     */

    public DataFlavor(Class<?> representationClass, String humanPresentableName) {

        this("application", "x-java-serialized-object", null, representationClass, humanPresentableName);

        if (representationClass == null) {

            throw new NullPointerException("representationClass");

        }

    }

    /**

     * Constructs a <code>DataFlavor</code> that represents a

     * <code>MimeType</code>.

     * <p>

     * The returned <code>DataFlavor</code> will have the following

     * characteristics:

     * <p>

     * If the <code>mimeType</code> is

     * "application/x-java-serialized-object; class=<representation class>",

     * the result is the same as calling

     * <code>new DataFlavor(Class:forName(&lt;representation class&gt;)</code>.

     * <p>

     * Otherwise:

     * <pre>

     *     representationClass = InputStream

     *     mimeType            = mimeType

     * </pre>

     * @param mimeType the string used to identify the MIME type for this flavor;

     *                 if the the <code>mimeType</code> does not specify a

     *                 "class=" parameter, or if the class is not successfully

     *                 loaded, then an <code>IllegalArgumentException</code>

     *                 is thrown

     * @param humanPresentableName the human-readable string used to identify

     *                 this flavor; if this parameter is <code>null</code>

     *                 then the value of the the MIME Content Type is used

     * @exception IllegalArgumentException if <code>mimeType</code> is

     *                 invalid or if the class is not successfully loaded

     * @exception NullPointerException if <code>mimeType</code> is null

     */

    public DataFlavor(String mimeType, String humanPresentableName) {

        super();

        if (mimeType == null) {

            throw new NullPointerException("mimeType");

        }

        try {

            initialize(mimeType, humanPresentableName, this.getClass().getClassLoader());

        } catch (MimeTypeParseException mtpe) {

            throw new IllegalArgumentException("failed to parse:" + mimeType);

        } catch (ClassNotFoundException cnfe) {

            throw new IllegalArgumentException("can't find specified class: " + cnfe.getMessage());

        }

    }

    /**

     * Constructs a <code>DataFlavor</code> that represents a

     * <code>MimeType</code>.

     * <p>

     * The returned <code>DataFlavor</code> will have the following

     * characteristics:

     * <p>

     * If the mimeType is

     * "application/x-java-serialized-object; class=<representation class>",

     * the result is the same as calling

     * <code>new DataFlavor(Class:forName(&lt;representation class&gt;)</code>.

     * <p>

     * Otherwise:

     * <pre>

     *     representationClass = InputStream

     *     mimeType            = mimeType

     * </pre>

     * @param mimeType the string used to identify the MIME type for this flavor

     * @param humanPresentableName the human-readable string used to

     *          identify this flavor

     * @param classLoader the class loader to use

     * @exception ClassNotFoundException if the class is not loaded

     * @exception IllegalArgumentException if <code>mimeType</code> is

     *                 invalid

     * @exception NullPointerException if <code>mimeType</code> is null

     */

    public DataFlavor(String mimeType, String humanPresentableName, ClassLoader classLoader) throws ClassNotFoundException {

        super();

        if (mimeType == null) {

            throw new NullPointerException("mimeType");

        }

        try {

            initialize(mimeType, humanPresentableName, classLoader);

        } catch (MimeTypeParseException mtpe) {

            throw new IllegalArgumentException("failed to parse:" + mimeType);

        }

    }

    /**

     * Constructs a <code>DataFlavor</code> from a <code>mimeType</code> string.

     * The string can specify a "class=<fully specified Java class name>"

     * parameter to create a <code>DataFlavor</code> with the desired

     * representation class. If the string does not contain "class=" parameter,

     * <code>java.io.InputStream</code> is used as default.

     *

     * @param mimeType the string used to identify the MIME type for this flavor;

     *                 if the class specified by "class=" parameter is not

     *                 successfully loaded, then an

     *                 <code>ClassNotFoundException</code> is thrown

     * @exception ClassNotFoundException if the class is not loaded

     * @exception IllegalArgumentException if <code>mimeType</code> is

     *                 invalid

     * @exception NullPointerException if <code>mimeType</code> is null

     */

    public DataFlavor(String mimeType) throws ClassNotFoundException {

        super();

        if (mimeType == null) {

            throw new NullPointerException("mimeType");

        }

        try {

            initialize(mimeType, null, this.getClass().getClassLoader());

        } catch (MimeTypeParseException mtpe) {

            throw new IllegalArgumentException("failed to parse:" + mimeType);

        }

    }

   /**

    * Common initialization code called from various constructors.

    *

    * @param mimeType the MIME Content Type (must have a class= param)

    * @param humanPresentableName the human Presentable Name or

    *                 <code>null</code>

    * @param classLoader the fallback class loader to resolve against

    *

    * @throws MimeTypeParseException

    * @throws ClassNotFoundException

    * @throws  NullPointerException if <code>mimeType</code> is null

    *

    * @see tryToLoadClass

    */

    private void initialize(String mimeType, String humanPresentableName, ClassLoader classLoader) throws MimeTypeParseException, ClassNotFoundException {

        if (mimeType == null) {

            throw new NullPointerException("mimeType");

        }

        this.mimeType = new MimeType(mimeType); // throws

        String rcn = getParameter("class");

        if (rcn == null) {

            if ("application/x-java-serialized-object".equals(this.mimeType.getBaseType()))

                throw new IllegalArgumentException("no representation class specified for:" + mimeType);

            else

                representationClass = java.io.InputStream.class; // default

        } else { // got a class name

            representationClass = DataFlavor.tryToLoadClass(rcn, classLoader);

        }

        this.mimeType.setParameter("class", representationClass.getName());

        if (humanPresentableName == null) {

            humanPresentableName = this.mimeType.getParameter("humanPresentableName");

            if (humanPresentableName == null)

                humanPresentableName = this.mimeType.getPrimaryType() + "/" + this.mimeType.getSubType();

        }

        this.humanPresentableName = humanPresentableName; // set it.

        this.mimeType.removeParameter("humanPresentableName"); // just in case

    }

    /**

     * String representation of this <code>DataFlavor</code> and its

     * parameters. The resulting <code>String</code> contains the name of

     * the <code>DataFlavor</code> class, this flavor's MIME type, and its

     * representation class. If this flavor has a primary MIME type of "text",

     * supports the charset parameter, and has an encoded representation, the

     * flavor's charset is also included. See <code>selectBestTextFlavor</code>

     * for a list of text flavors which support the charset parameter.

     *

     * @return  string representation of this <code>DataFlavor</code>

     * @see #selectBestTextFlavor

     */

    public String toString() {

        String string = getClass().getName();

        string += "["+paramString()+"]";

        return string;

    }

    private String paramString() {

        String params = "";

        params += "mimetype=";

        if (mimeType == null) {

            params += "null";

        } else {

            params += mimeType.getBaseType();

        }

        params += ";representationclass=";

        if (representationClass == null) {

           params += "null";

        } else {

           params += representationClass.getName();

        }

        if (DataTransferer.isFlavorCharsetTextType(this) &&

            (isRepresentationClassInputStream() ||

             isRepresentationClassByteBuffer() ||

             DataTransferer.byteArrayClass.equals(representationClass)))

        {

            params += ";charset=" + DataTransferer.getTextCharset(this);

        }

        return params;

    }

    /**

     * Returns a <code>DataFlavor</code> representing plain text with Unicode

     * encoding, where:

     * <pre>

     *     representationClass = java.io.InputStream

     *     mimeType            = "text/plain;

     *                            charset=<platform default Unicode encoding>"

     * </pre>

     * Sun's implementation for Microsoft Windows uses the encoding <code>utf-16le</code>.