/*
 * @(#)JTextField.java	1.59 01/11/29
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.swing;

import java.awt.*;
import java.awt.event.*;
import javax.swing.text.*;
import javax.swing.plaf.*;
import javax.swing.event.*;
import javax.accessibility.*;

import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;

/**
 * JTextField is a lightweight component that allows the editing 
 * of a single line of text.  It is intended to be source-compatible
 * with java.awt.TextField where it is reasonable to do so.  This
 * component has capabilities not found in the java.awt.TextField 
 * class.  The superclass should be consulted for additional capabilities.
 * <p>
 * JTextField has a method to establish the string used as the
 * command string for the action event that gets fired.  The
 * java.awt.TextField used the text of the field as the command
 * string for the ActionEvent.  JTextField will use the command
 * string set with the <code>setActionCommand</code> method if not null, 
 * otherwise it will use the text of the field as a compatibility with 
 * java.awt.TextField.
 * <p>
 * The method <code>setEchoChar</code> and <code>getEchoChar</code>
 * are not provided directly to avoid a new implementation of a
 * pluggable look-and-feel inadvertantly exposing password characters.
 * To provide password-like services a seperate class JPasswordField
 * extends JTextField to provide this service with an independantly
 * pluggable look-and-feel.
 * <p>
 * The java.awt.TextField could be monitored for changes by adding
 * a TextListener for TextEvent's.  In the JTextComponent based
 * components, changes are broadcasted from the model via a
 * DocumentEvent to DocumentListeners.  The DocumentEvent gives 
 * the location of the change and the kind of change if desired.
 * The code fragment might look something like:
 * <pre><code>
 *    DocumentListener myListener = ??;
 *    JTextField myArea = ??;
 *    myArea.getDocument().addDocumentListener(myListener);
 * </code></pre>
 * <p>
 * The horizontal alignment of JTextField can be set to be left
 * justified, centered, or right justified if the required size
 * of the field text is smaller than the size allocated to it.
 * This is determined by the <code>setHorizontalAlignment</code>
 * and <code>getHorizontalAlignment</code> methods.  The default
 * is to be left justified.
 * <p>
 * For the keyboard keys used by this component in the standard Look and
 * Feel (L&F) renditions, see the
 * <a href="doc-files/Key-Index.html#JTextField">JTextField</a> key assignments.
 * <p>
 * For compatibility with java.awt.TextField, the VK_ENTER key fires
 * the ActionEvent to the registered ActionListeners.  However, awt
 * didn't have default buttons like swing does.  If a text field has
 * focus and the VK_ENTER key is pressed, it will fire the fields
 * ActionEvent rather than activate the default button.  To disable
 * the compatibility with awt for text fields, the following code
 * fragment will remove the binding of VK_ENTER from the default keymap
 * used by all JTextFields if that is desired.
 * <pre><code>

  static {
    JTextField f = new JTextField();
    KeyStroke enter = KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0);
    Keymap map = f.getKeymap();
    map.removeKeyStrokeBinding(enter);
  }

 * </code></pre>
 * <p>
 * Customized fields can easily be created by extending the model and
 * changing the default model provided.  For example, the following piece
 * of code will create a field that holds only upper case characters.  It
 * will work even if text is pasted into from the clipboard or it is altered via 
 * programmatic changes.
 * <pre><code>

public class UpperCaseField extends JTextField {

    public UpperCaseField(int cols) {
	super(cols);
    }

    protected Document createDefaultModel() {
	return new UpperCaseDocument();
    }

    static class UpperCaseDocument extends PlainDocument {

        public void insertString(int offs, String str, AttributeSet a) 
	    throws BadLocationException {

	    if (str == null) {
		return;
	    }
	    char[] upper = str.toCharArray();
	    for (int i = 0; i < upper.length; i++) {
		upper[i] = Character.toUpperCase(upper[i]);
	    }
	    super.insertString(offs, new String(upper), a);
	}
    }
}

 * </code></pre>
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @beaninfo
 *   attribute: isContainer false
 *
 * @author  Timothy Prinzing
 * @version 1.59 11/29/01
 * @see #setActionCommand
 * @see JPasswordField
 */
public class JTextField extends JTextComponent implements SwingConstants {

    /**
     * Constructs a new TextField.  A default model is created, the initial
     * string is null, and the number of columns is set to 0.
     */
    public JTextField() {
        this(null, null, 0);
    }

    /**
     * Constructs a new TextField initialized with the specified text.
     * A default model is created and the number of columns is 0.
     *
     * @param text the text to be displayed, or null
     */
    public JTextField(String text) {
        this(null, text, 0);
    }

    /**
     * Constructs a new empty TextField with the specified number of columns.
     * A default model is created and the initial string is set to null.
     *
     * @param columns  the number of columns to use to calculate 
     *   the preferred width.  If columns is set to zero, the
     *   preferred width will be whatever naturally results from
     *   the component implementation.
     */ 
    public JTextField(int columns) {
        this(null, null, columns);
    }

    /**
     * Constructs a new TextField initialized with the specified text
     * and columns.  A default model is created.
     *
     * @param text the text to be displayed, or null
     * @param columns  the number of columns to use to calculate 
     *   the preferred width.  If columns is set to zero, the
     *   preferred width will be whatever naturally results from
     *   the component implementation.
     */
    public JTextField(String text, int columns) {
        this(null, text, columns);
    }

    /**
     * Constructs a new JTextField that uses the given text storage
     * model and the given number of columns.  This is the constructor
     * through which the other constructors feed.  If the document is null,
     * a default model is created.
     *
     * @param doc  the text storage to use.  If this is null, a default
     *   will be provided by calling the createDefaultModel method.
     * @param text  the initial string to display, or null
     * @param columns  the number of columns to use to calculate 
     *   the preferred width >= 0.  If columns is set to zero, the
     *   preferred width will be whatever naturally results from
     *   the component implementation.
     * @exception IllegalArgumentException if columns < 0
     */
    public JTextField(Document doc, String text, int columns) {
        if (columns < 0) {
            throw new IllegalArgumentException("columns less than zero.");
        }
        visibility = new DefaultBoundedRangeModel();
        visibility.addChangeListener(new ScrollRepainter());
        this.columns = columns;
        if (doc == null) {
            doc = createDefaultModel();
        }
        setDocument(doc);
        if (text != null) {
            setText(text);
        }
    }

    /**
     * Gets the class ID for a UI.
     *
     * @return the ID ("TextFieldUI")
     * @see JComponent#getUIClassID
     * @see UIDefaults#getUI
     */
    public String getUIClassID() {
        return uiClassID;
    }

    
    /**
     * Calls to revalidate that come from within the textfield itself will
     * be handled by validating the textfield. 
     * 
     * @see JComponent#revalidate
     * @see JComponent#isValidateRoot
     */
    public boolean isValidateRoot() {
        return true;
    }


    /**
     * Returns the horizontal alignment of the text.
     * Valid keys: JTextField.LEFT (the default), JTextField.CENTER,
     * JTextField.RIGHT.
     *
     * @return the alignment
     */
    public int getHorizontalAlignment() {
        return horizontalAlignment;
    }
    
    /**
     * Sets the horizontal alignment of the text.
     * Valid keys: JTextField.LEFT (the default), JTextField.CENTER,
     * JTextField.RIGHT.  invalidate() and repaint() are called when the
     * alignment is set, and a PropertyChange event ("horizontalAlignment")
     * is fired.
     *
     * @param alignment the alignment
     * @exception IllegalArgumentException if the alignment
     *  specified is not a valid key.
     * @beaninfo
     *   preferred: true
     *       bound: true
     * description: Set the field alignment to LEFT (the default), CENTER, RIGHT
     *        enum: LEFT JTextField.LEFT CENTER JTextField.CENTER RIGHT JTextField.RIGHT
     */
     public void setHorizontalAlignment(int alignment) {
        if (alignment == horizontalAlignment) return;
        int oldValue = horizontalAlignment;
        if ((alignment == LEFT) || (alignment == CENTER) || (alignment == RIGHT)) {
            horizontalAlignment = alignment;
        } else {
            throw new IllegalArgumentException("horizontalAlignment");
        }
        firePropertyChange("horizontalAlignment", oldValue, horizontalAlignment);       
        invalidate();
        repaint();
    }

    /**
     * Creates the default implementation of the model
     * to be used at construction if one isn't explicitly 
     * given.  An instance of PlainDocument is returned.
     *
     * @return the default model implementation
     */
    protected Document createDefaultModel() {
        return new PlainDocument();
    }

    /**
     * Returns the number of columns in this TextField.
     *
     * @return the number of columns >= 0
     */
    public int getColumns() {
        return columns;
    }

    /**
     * Sets the number of columns in this TextField, and then invalidate
     * the layout.
     *
     * @param columns the number of columns >= 0
     * @exception IllegalArgumentException if columns is less than 0
     * @beaninfo
     * description: the number of columns preferred for display
     */
    public void setColumns(int columns) {
        int oldVal = this.columns;
        if (columns < 0) {
            throw new IllegalArgumentException("columns less than zero.");
        }
        if (columns != oldVal) {
            this.columns = columns;
            invalidate();
        }
    }

    /**
     * Gets the column width.
     * The meaning of what a column is can be considered a fairly weak
     * notion for some fonts.  This method is used to define the width
     * of a column.  By default this is defined to be the width of the
     * character <em>m</em> for the font used.  This method can be 
     * redefined to be some alternative amount
     *
     * @return the column width >= 1
     */
    protected int getColumnWidth() {
        if (columnWidth == 0) {
            FontMetrics metrics = getFontMetrics(getFont());
            columnWidth = metrics.charWidth('m');
        }
        return columnWidth;
    }

    /**
     * Returns the preferred size Dimensions needed for this 
     * TextField.  If a non-zero number of columns has been
     * set, the width is set to the columns multiplied by
     * the column width. 
     *
     * @return the dimensions
     */
    public Dimension getPreferredSize() {
        synchronized (getTreeLock()) {
            Dimension size = super.getPreferredSize();
            if (columns != 0) {
                size.width = columns * getColumnWidth();
            }
            return size;
        }
    }

    /**
     * Sets the current font.  This removes cached row height and column
     * width so the new font will be reflected.  revalidate() is called
     * after setting the font.
     *
     * @param f the new font
     */
    public void setFont(Font f) {
        super.setFont(f);
        columnWidth = 0;
    }

    /**
     * Adds the specified action listener to receive 
     * action events from this textfield.
     *
     * @param l the action listener
     */ 
    public synchronized void addActionListener(ActionListener l) {
        listenerList.add(ActionListener.class, l);
    }

    /**
     * Removes the specified action listener so that it no longer
     * receives action events from this textfield.
     *
     * @param l the action listener 
     */ 
    public synchronized void removeActionListener(ActionListener l) {
        listenerList.remove(ActionListener.class, l);
    }

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type.  The event instance 
     * is lazily created using the parameters passed into 
     * the fire method.  The listener list is processed in last to
     * first order.
     * @see EventListenerList
     */
    protected void fireActionPerformed() {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED,
                                        (command != null) ? command : getText());
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==ActionListener.class) {
                ((ActionListener)listeners[i+1]).actionPerformed(e);
            }          
        }
    }

    /**
     * Sets the command string used for action events.
     *
     * @param command the command string
     */
    public void setActionCommand(String command) {
        this.command = command;
    }

    /**
     * Fetches the command list for the editor.  This is
     * the list of commands supported by the plugged-in UI
     * augmented by the collection of commands that the
     * editor itself supports.  These are useful for binding
     * to events, such as in a keymap.
     *
     * @return the command list
     */
    public Action[] getActions() {
        return TextAction.augmentList(super.getActions(), defaultActions);
    }

    /** 
     * Processes action events occurring on this textfield by
     * dispatching them to any registered ActionListener objects.
     * This is normally called by the controller registered with
     * textfield.
     */  
    public void postActionEvent() {
        fireActionPerformed();
    }

    // --- Scrolling support -----------------------------------

    /**
     * Gets the visibility of the text field.  This can
     * be adjusted to change the location of the visible
     * area if the size of the field is greater than
     * the area that was allocated to the field.
     *
     * The fields look-and-feel implementation manages
     * the values of the minimum, maximum, and extent
     * properties on the BoundedRangeModel.
     * 
     * @return the visibility
     * @see BoundedRangeModel
     */
    public BoundedRangeModel getHorizontalVisibility() {
        return visibility;
    }

    /**
     * Gets the scroll offset.
     *
     * @return the offset >= 0
     */
    public int getScrollOffset() {
        return visibility.getValue();
    }

    /**
     * Sets the scroll offset.
     *
     * @param scrollOffset the offset >= 0
     */
    public void setScrollOffset(int scrollOffset) {
        visibility.setValue(scrollOffset);
    }
    
    /**
     * Scrolls the field left or right.
     *
     * @param r the region to scroll
     */
    public void scrollRectToVisible(Rectangle r) {
        // convert to coordinate system of the bounded range
        int x = r.x + visibility.getValue();
        if (x < visibility.getValue()) {
            // Scroll to the left
            visibility.setValue(x - 2);
        } else if(x > visibility.getValue() + visibility.getExtent()) {
            // Scroll to the right
            visibility.setValue(x - visibility.getExtent() + 2);
        }
    }

    // --- variables -------------------------------------------

    /**
     * Name of the action to send notification that the
     * contents of the field have been accepted.  Typically
     * this is bound to a carriage-return.
     */
    public static final String notifyAction = "notify-field-accept";

    private BoundedRangeModel visibility;
    private int horizontalAlignment  = LEFT;
    private int columns;
    private int columnWidth;
    private String command;

    private static final Action[] defaultActions = {
        new NotifyAction()
    };

    /**
     * @see #getUIClassID
     * @see #readObject
     */
    private static final String uiClassID = "TextFieldUI";

    // --- Action implementations -----------------------------------

    static class NotifyAction extends TextAction {

        NotifyAction() {
            super(notifyAction);
        }

        public void actionPerformed(ActionEvent e) {
            JTextComponent target = getFocusedComponent();
            if (target instanceof JTextField) {
                JTextField field = (JTextField) target;
                field.postActionEvent();
            }
        }
    }

    class ScrollRepainter implements ChangeListener {

        public void stateChanged(ChangeEvent e) {
            repaint();
        }

    }


    /** 
     * See readObject() and writeObject() in JComponent for more 
     * information about serialization in Swing.
     */
    private void writeObject(ObjectOutputStream s) throws IOException {
        s.defaultWriteObject();
	if ((ui != null) && (getUIClassID().equals(uiClassID))) {
	    ui.installUI(this);
	}
    }


    /**
     * Returns a string representation of this JTextField. This method 
     * is intended to be used only for debugging purposes, and the 
     * content and format of the returned string may vary between      
     * implementations. The returned string may be empty but may not 
     * be <code>null</code>.
     * 
     * @return  a string representation of this JTextField.
     */
    protected String paramString() {
        String horizontalAlignmentString;
        if (horizontalAlignment == LEFT) {
	    horizontalAlignmentString = "LEFT";
	} else if (horizontalAlignment == CENTER) {
	    horizontalAlignmentString = "CENTER";
	} else if (horizontalAlignment == RIGHT) {
	    horizontalAlignmentString = "RIGHT";
	} else horizontalAlignmentString = "";
        String commandString = (command != null ?
				command : "");

        return super.paramString() +
        ",columns=" + columns +
        ",columnWidth=" + columnWidth +
        ",command=" + commandString +
        ",horizontalAlignment=" + horizontalAlignmentString;
    }


/////////////////
// Accessibility support
////////////////


    /**
     * Get the AccessibleContext associated with this JTextField.
     * Creates a new context if necessary.
     *
     * @return the AccessibleContext of this JTextField
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleJTextField();
        }
        return accessibleContext;
    }

    /**
     * The class used to obtain the accessible role for this object.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases.  The current serialization support is appropriate
     * for short term storage or RMI between applications running the same
     * version of Swing.  A future release of Swing will provide support for
     * long term persistence.
     */
    protected class AccessibleJTextField extends AccessibleJTextComponent {

        /**
         * Gets the state set of this object.
         *
         * @return an instance of AccessibleStateSet describing the states 
         * of the object
         * @see AccessibleState
         */
        public AccessibleStateSet getAccessibleStateSet() {
            AccessibleStateSet states = super.getAccessibleStateSet();
            states.add(AccessibleState.SINGLE_LINE);
            return states;
        }
    }
}