/*

 * Copyright 1995-2006 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;

import java.awt.peer.TextComponentPeer;

import java.awt.event.*;

import java.util.EventListener;

import java.io.ObjectOutputStream;

import java.io.ObjectInputStream;

import java.io.IOException;

import sun.awt.InputMethodSupport;

import java.text.BreakIterator;

import javax.swing.text.AttributeSet;

import javax.accessibility.*;

import java.awt.im.InputMethodRequests;

/**

 * The <code>TextComponent</code> class is the superclass of

 * any component that allows the editing of some text.

 * <p>

 * A text component embodies a string of text.  The

 * <code>TextComponent</code> class defines a set of methods

 * that determine whether or not this text is editable. If the

 * component is editable, it defines another set of methods

 * that supports a text insertion caret.

 * <p>

 * In addition, the class defines methods that are used

 * to maintain a current <em>selection</em> from the text.

 * The text selection, a substring of the component's text,

 * is the target of editing operations. It is also referred

 * to as the <em>selected text</em>.

 *

 * @author      Sami Shaio

 * @author      Arthur van Hoff

 * @since       JDK1.0

 */

public class TextComponent extends Component implements Accessible {

    /**

     * The value of the text.

     * A <code>null</code> value is the same as "".

     *

     * @serial

     * @see #setText(String)

     * @see #getText()

     */

    String text;

    /**

     * A boolean indicating whether or not this

     * <code>TextComponent</code> is editable.

     * It will be <code>true</code> if the text component

     * is editable and <code>false</code> if not.

     *

     * @serial

     * @see #isEditable()

     */

    boolean editable = true;

    /**

     * The selection refers to the selected text, and the

     * <code>selectionStart</code> is the start position

     * of the selected text.

     *

     * @serial

     * @see #getSelectionStart()

     * @see #setSelectionStart(int)

     */

    int selectionStart;

    /**

     * The selection refers to the selected text, and the

     * <code>selectionEnd</code>

     * is the end position of the selected text.

     *

     * @serial

     * @see #getSelectionEnd()

     * @see #setSelectionEnd(int)

     */

    int selectionEnd;

    // A flag used to tell whether the background has been set by

    // developer code (as opposed to AWT code).  Used to determine

    // the background color of non-editable TextComponents.

    boolean backgroundSetByClientCode = false;

    /**

     * True if this <code>TextComponent</code> has access

     * to the System clipboard.

     */

    transient private boolean canAccessClipboard;

    transient protected TextListener textListener;

    /*

     * JDK 1.1 serialVersionUID

     */

    private static final long serialVersionUID = -2214773872412987419L;

    /**

     * Constructs a new text component initialized with the

     * specified text. Sets the value of the cursor to

     * <code>Cursor.TEXT_CURSOR</code>.

     * @param      text       the text to be displayed; if

     *             <code>text</code> is <code>null</code>, the empty

     *             string <code>""</code> will be displayed

     * @exception  HeadlessException if

     *             <code>GraphicsEnvironment.isHeadless</code>

     *             returns true

     * @see        java.awt.GraphicsEnvironment#isHeadless

     * @see        java.awt.Cursor

     */

    TextComponent(String text) throws HeadlessException {

        GraphicsEnvironment.checkHeadless();

        this.text = (text != null) ? text : "";

        setCursor(Cursor.getPredefinedCursor(Cursor.TEXT_CURSOR));

        checkSystemClipboardAccess();

    }

    private void enableInputMethodsIfNecessary() {

        if (checkForEnableIM) {

            checkForEnableIM = false;

            try {

                Toolkit toolkit = Toolkit.getDefaultToolkit();

                boolean shouldEnable = false;

                if (toolkit instanceof InputMethodSupport) {

                    shouldEnable = ((InputMethodSupport)toolkit)

                      .enableInputMethodsForTextComponent();

                }

                enableInputMethods(shouldEnable);

            } catch (Exception e) {

                // if something bad happens, just don't enable input methods

            }

        }

    }

    /**

     * Enables or disables input method support for this text component. If input

     * method support is enabled and the text component also processes key events,

     * incoming events are offered to the current input method and will only be

     * processed by the component or dispatched to its listeners if the input method

     * does not consume them. Whether and how input method support for this text

     * component is enabled or disabled by default is implementation dependent.

     *

     * @param enable true to enable, false to disable

     * @see #processKeyEvent

     * @since 1.2

     */

    public void enableInputMethods(boolean enable) {

        checkForEnableIM = false;

        super.enableInputMethods(enable);

    }

    boolean areInputMethodsEnabled() {

        // moved from the constructor above to here and addNotify below,

        // this call will initialize the toolkit if not already initialized.

        if (checkForEnableIM) {

            enableInputMethodsIfNecessary();

        }

        // TextComponent handles key events without touching the eventMask or

        // having a key listener, so just check whether the flag is set

        return (eventMask & AWTEvent.INPUT_METHODS_ENABLED_MASK) != 0;

    }

    public InputMethodRequests getInputMethodRequests() {

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) return peer.getInputMethodRequests();

        else return null;

    }

    /**

     * Makes this Component displayable by connecting it to a

     * native screen resource.

     * This method is called internally by the toolkit and should

     * not be called directly by programs.

     * @see       java.awt.TextComponent#removeNotify

     */

    public void addNotify() {

        super.addNotify();

        enableInputMethodsIfNecessary();

    }

    /**

     * Removes the <code>TextComponent</code>'s peer.

     * The peer allows us to modify the appearance of the

     * <code>TextComponent</code> without changing its

     * functionality.

     */

    public void removeNotify() {

        synchronized (getTreeLock()) {

            TextComponentPeer peer = (TextComponentPeer)this.peer;

            if (peer != null) {

                text = peer.getText();

                selectionStart = peer.getSelectionStart();

                selectionEnd = peer.getSelectionEnd();

            }

            super.removeNotify();

        }

    }

    /**

     * Sets the text that is presented by this

     * text component to be the specified text.

     * @param       t   the new text;

     *                  if this parameter is <code>null</code> then

     *                  the text is set to the empty string ""

     * @see         java.awt.TextComponent#getText

     */

    public synchronized void setText(String t) {

        text = (t != null) ? t : "";

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            peer.setText(text);

        }

    }

    /**

     * Returns the text that is presented by this text component.

     * By default, this is an empty string.

     *

     * @return the value of this <code>TextComponent</code>

     * @see     java.awt.TextComponent#setText

     */

    public synchronized String getText() {

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            text = peer.getText();

        }

        return text;

    }

    /**

     * Returns the selected text from the text that is

     * presented by this text component.

     * @return      the selected text of this text component

     * @see         java.awt.TextComponent#select

     */

    public synchronized String getSelectedText() {

        return getText().substring(getSelectionStart(), getSelectionEnd());

    }

    /**

     * Indicates whether or not this text component is editable.

     * @return     <code>true</code> if this text component is

     *                  editable; <code>false</code> otherwise.

     * @see        java.awt.TextComponent#setEditable

     * @since      JDK1.0

     */

    public boolean isEditable() {

        return editable;

    }

    /**

     * Sets the flag that determines whether or not this

     * text component is editable.

     * <p>

     * If the flag is set to <code>true</code>, this text component

     * becomes user editable. If the flag is set to <code>false</code>,

     * the user cannot change the text of this text component.

     * By default, non-editable text components have a background color

     * of SystemColor.control.  This default can be overridden by

     * calling setBackground.

     *

     * @param     b   a flag indicating whether this text component

     *                      is user editable.

     * @see       java.awt.TextComponent#isEditable

     * @since     JDK1.0

     */

    public synchronized void setEditable(boolean b) {

        if (editable == b) {

            return;

        }

        editable = b;

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            peer.setEditable(b);

        }

    }

    /**

     * Gets the background color of this text component.

     *

     * By default, non-editable text components have a background color

     * of SystemColor.control.  This default can be overridden by

     * calling setBackground.

     *

     * @return This text component's background color.

     *         If this text component does not have a background color,

     *         the background color of its parent is returned.

     * @see #setBackground(Color)

     * @since JDK1.0

     */

    public Color getBackground() {

        if (!editable && !backgroundSetByClientCode) {

            return SystemColor.control;

        }

        return super.getBackground();

    }

    /**

     * Sets the background color of this text component.

     *

     * @param c The color to become this text component's color.

     *        If this parameter is null then this text component

     *        will inherit the background color of its parent.

     * @see #getBackground()

     * @since JDK1.0

     */

    public void setBackground(Color c) {

        backgroundSetByClientCode = true;

        super.setBackground(c);

    }

    /**

     * Gets the start position of the selected text in

     * this text component.

     * @return      the start position of the selected text

     * @see         java.awt.TextComponent#setSelectionStart

     * @see         java.awt.TextComponent#getSelectionEnd

     */

    public synchronized int getSelectionStart() {

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            selectionStart = peer.getSelectionStart();

        }

        return selectionStart;

    }

    /**

     * Sets the selection start for this text component to

     * the specified position. The new start point is constrained

     * to be at or before the current selection end. It also

     * cannot be set to less than zero, the beginning of the

     * component's text.

     * If the caller supplies a value for <code>selectionStart</code>

     * that is out of bounds, the method enforces these constraints

     * silently, and without failure.

     * @param       selectionStart   the start position of the

     *                        selected text

     * @see         java.awt.TextComponent#getSelectionStart

     * @see         java.awt.TextComponent#setSelectionEnd

     * @since       JDK1.1

     */

    public synchronized void setSelectionStart(int selectionStart) {

        /* Route through select method to enforce consistent policy

         * between selectionStart and selectionEnd.

         */

        select(selectionStart, getSelectionEnd());

    }

    /**

     * Gets the end position of the selected text in

     * this text component.

     * @return      the end position of the selected text

     * @see         java.awt.TextComponent#setSelectionEnd

     * @see         java.awt.TextComponent#getSelectionStart

     */

    public synchronized int getSelectionEnd() {

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            selectionEnd = peer.getSelectionEnd();

        }

        return selectionEnd;

    }

    /**

     * Sets the selection end for this text component to

     * the specified position. The new end point is constrained

     * to be at or after the current selection start. It also

     * cannot be set beyond the end of the component's text.

     * If the caller supplies a value for <code>selectionEnd</code>

     * that is out of bounds, the method enforces these constraints

     * silently, and without failure.

     * @param       selectionEnd   the end position of the

     *                        selected text

     * @see         java.awt.TextComponent#getSelectionEnd

     * @see         java.awt.TextComponent#setSelectionStart

     * @since       JDK1.1

     */

    public synchronized void setSelectionEnd(int selectionEnd) {

        /* Route through select method to enforce consistent policy

         * between selectionStart and selectionEnd.

         */

        select(getSelectionStart(), selectionEnd);

    }

    /**

     * Selects the text between the specified start and end positions.

     * <p>

     * This method sets the start and end positions of the

     * selected text, enforcing the restriction that the start position

     * must be greater than or equal to zero.  The end position must be

     * greater than or equal to the start position, and less than or

     * equal to the length of the text component's text.  The

     * character positions are indexed starting with zero.

     * The length of the selection is

     * <code>endPosition</code> - <code>startPosition</code>, so the

     * character at <code>endPosition</code> is not selected.

     * If the start and end positions of the selected text are equal,

     * all text is deselected.

     * <p>

     * If the caller supplies values that are inconsistent or out of

     * bounds, the method enforces these constraints silently, and

     * without failure. Specifically, if the start position or end

     * position is greater than the length of the text, it is reset to

     * equal the text length. If the start position is less than zero,

     * it is reset to zero, and if the end position is less than the

     * start position, it is reset to the start position.

     *

     * @param        selectionStart the zero-based index of the first

                       character (<code>char</code> value) to be selected

     * @param        selectionEnd the zero-based end position of the

                       text to be selected; the character (<code>char</code> value) at

                       <code>selectionEnd</code> is not selected

     * @see          java.awt.TextComponent#setSelectionStart

     * @see          java.awt.TextComponent#setSelectionEnd

     * @see          java.awt.TextComponent#selectAll

     */

    public synchronized void select(int selectionStart, int selectionEnd) {

        String text = getText();

        if (selectionStart < 0) {

            selectionStart = 0;

        }

        if (selectionStart > text.length()) {

            selectionStart = text.length();

        }

        if (selectionEnd > text.length()) {

            selectionEnd = text.length();

        }

        if (selectionEnd < selectionStart) {

            selectionEnd = selectionStart;

        }

        this.selectionStart = selectionStart;

        this.selectionEnd = selectionEnd;

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            peer.select(selectionStart, selectionEnd);

        }

    }

    /**

     * Selects all the text in this text component.

     * @see        java.awt.TextComponent#select

     */

    public synchronized void selectAll() {

        this.selectionStart = 0;

        this.selectionEnd = getText().length();

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            peer.select(selectionStart, selectionEnd);

        }

    }

    /**

     * Sets the position of the text insertion caret.

     * The caret position is constrained to be between 0

     * and the last character of the text, inclusive.

     * If the passed-in value is greater than this range,

     * the value is set to the last character (or 0 if

     * the <code>TextComponent</code> contains no text)

     * and no error is returned.  If the passed-in value is

     * less than 0, an <code>IllegalArgumentException</code>

     * is thrown.

     *

     * @param        position the position of the text insertion caret

     * @exception    IllegalArgumentException if <code>position</code>

     *               is less than zero

     * @since        JDK1.1

     */

    public synchronized void setCaretPosition(int position) {

        if (position < 0) {

            throw new IllegalArgumentException("position less than zero.");

        }

        int maxposition = getText().length();

        if (position > maxposition) {

            position = maxposition;

        }

        TextComponentPeer peer = (TextComponentPeer)this.peer;

        if (peer != null) {

            peer.setCaretPosition(position);

        } else {

            select(position, position);

        }

    }

    /**

     * Returns the position of the text insertion caret.

     * The caret position is constrained to be between 0

     * and the last character of the text, inclusive.

     * If the text or caret have not been set, the default

     * caret position is 0.

     *

     * @return       the position of the text insertion caret

     * @see #setCaretPosition(int)

     * @since        JDK1.1