/*
 * @(#)TextField.java	1.63 00/04/06
 *
 * Copyright 1995-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */
package java.awt;

import java.awt.peer.TextFieldPeer;
import java.awt.event.*;
import java.util.EventListener;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import javax.accessibility.*;


/**
 * A <code>TextField</code> object is a text component
 * that allows for the editing of a single line of text.
 * <p>
 * For example, the following image depicts a frame with four
 * text fields of varying widths. Two of these text fields
 * display the predefined text <code>"Hello"</code>.
 * <p>
 * <img src="doc-files/TextField-1.gif"
 * ALIGN=center HSPACE=10 VSPACE=7>
 * <p>
 * Here is the code that produces these four text fields:
 * <p>
 * <hr><blockquote><pre>
 * TextField tf1, tf2, tf3, tf4;
 * // a blank text field
 * tf1 = new TextField();
 * // blank field of 20 columns
 * tf2 = new TextField("", 20);
 * // predefined text displayed
 * tf3 = new TextField("Hello!");
 * // predefined text in 30 columns
 * tf4 = new TextField("Hello", 30);
 * </pre></blockquote><hr>
 * <p>
 * Every time the user types a key in the text field, one or 
 * more key events are sent to the text field.  A <code>KeyEvent</code> 
 * may be one of three types: keyPressed, keyReleased, or keyTyped. 
 * The properties of a key event indicate which of these types 
 * it is, as well as additional information about the event, 
 * such as what modifiers are applied to the key event and the 
 * time at which the event occurred.  
 * <p>
 * The key event is passed to every <code>KeyListener</code>
 * or <code>KeyAdapter</code> object which registered to receive such
 * events using the component's <code>addKeyListener</code> method.
 * (<code>KeyAdapter</code> objects implement the 
 * <code>KeyListener</code> interface.)  
 * <p>
 * It is also possible to fire an <code>ActionEvent</code>.  
 * If action events are enabled for the text field, they may 
 * be fired by pressing the <code>Return</code> key.  
 * <p>
 * The <code>TextField</code> class's <code>processEvent</code>
 * method examines the action event and passes it along to
 * <code>processActionEvent</code>. The latter method redirects the
 * event to any <code>ActionListener</code> objects that have
 * registered to receive action events generated by this
 * text field.
 *
 * @version	1.63, 04/06/00
 * @author 	Sami Shaio
 * @see         java.awt.event.KeyEvent
 * @see         java.awt.event.KeyAdapter
 * @see         java.awt.event.KeyListener
 * @see         java.awt.event.ActionEvent
 * @see         java.awt.Component#addKeyListener
 * @see         java.awt.TextField#processEvent
 * @see         java.awt.TextField#processActionEvent
 * @see         java.awt.TextField#addActionListener
 * @since       JDK1.0
 */
public class TextField extends TextComponent {

    /**
     * The number of columns in the text field.
     * A column is an approximate average character 
     * width that is platform-dependent.
     * Guaranteed to be non-negative. 
     *
     * @serial
     * @see setColumns()
     * @see getColumns()
     */
    int columns;

    /**
     * The echo character, which is used when
     * the user wishes to disguise the characters
     * typed into the text field.
     * The disguises are removed if echoChar = <code>0</code>. 
     *
     * @serial
     * @see getEchoChar()
     * @see setEchoChar()
     * @see echoCharIsSet()
     */
    char echoChar;

    transient ActionListener actionListener;

    private static final String base = "textfield";
    private static int nameCounter = 0;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = -2966288784432217853L;

    /**
     * Initialize JNI field and method ids 
     */
    private static native void initIDs();

    static {
        /* ensure that the necessary native libraries are loaded */
	Toolkit.loadLibraries();
	initIDs();
    }

    /**
     * Constructs a new text field.
     */
    public TextField() {
	this("", 0);
    }

    /**
     * Constructs a new text field initialized with the specified text.
     * @param      text       the text to be displayed. If
     *             <code>text</code> is <code>null</code>, the empty
     *             string <code>""</code> will be displayed.
     */
    public TextField(String text) {
        this(text, (text != null) ? text.length() : 0);
    }

    /**
     * Constructs a new empty text field with the specified number 
     * of columns.  A column is an approximate average character 
     * width that is platform-dependent.
     * @param      columns     the number of columns.  If 
     *             <code>columns</code> is less than <code>0</code>, 
     *             <code>columns</code> is set to <code>0</code>. 
     */
    public TextField(int columns) {
	this("", columns);
    }

    /**
     * Constructs a new text field initialized with the specified text
     * to be displayed, and wide enough to hold the specified
     * number of columns. A column is an approximate average character
     * width that is platform-dependent.
     * @param      text       the text to be displayed. If
     *             <code>text</code> is <code>null</code>, the empty
     *             string <code>""</code> will be displayed.
     * @param      columns     the number of columns.  If 
     *             <code>columns</code> is less than <code>0</code>, 
     *             <code>columns</code> is set to <code>0</code>. 
     */
    public TextField(String text, int columns) {
	super(text);
        this.columns = (columns >= 0) ? columns : 0;
    }

    /**
     * Construct a name for this component.  Called by getName() when the
     * name is null.
     */
    String constructComponentName() {
        synchronized (getClass()) {
	    return base + nameCounter++;
	}
    }

    /**
     * Creates the TextField's peer.  The peer allows us to modify the
     * appearance of the TextField without changing its functionality.
     */
    public void addNotify() {
        synchronized (getTreeLock()) {
	    if (peer == null)
	        peer = getToolkit().createTextField(this);
	    super.addNotify();
	}
    }

    /**
     * Gets the character that is to be used for echoing.
     * <p>
     * An echo character is useful for text fields where
     * user input should not be echoed to the screen, as in
     * the case of a text field for entering a password.
     * If <code>echoChar</code> = <code>0</code>, user 
     * input is echoed to the screen unchanged.  
     * @return      the echo character for this text field.
     * @see         java.awt.TextField#echoCharIsSet
     * @see         java.awt.TextField#setEchoChar
     */
    public char getEchoChar() {
	return echoChar;
    }

    /**
     * Sets the echo character for this text field.
     * <p>
     * An echo character is useful for text fields where
     * user input should not be echoed to the screen, as in
     * the case of a text field for entering a password.
     * Setting <code>echoChar</code> = <code>0</code> allows 
     * user input to be echoed to the screen again.  
     * @param       c   the echo character for this text field.
     * @see         java.awt.TextField#echoCharIsSet
     * @see         java.awt.TextField#getEchoChar
     * @since       JDK1.1
     */
    public void setEchoChar(char c) {
	setEchoCharacter(c);
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>setEchoChar(char)</code>.
     */
    public synchronized void setEchoCharacter(char c) {
	echoChar = c;
	TextFieldPeer peer = (TextFieldPeer)this.peer;
	if (peer != null) {
	    peer.setEchoCharacter(c);
	}
    }

    /**
     * Sets the text that is presented by this 
     * text component to be the specified text. 
     * @param       t   the new text.
     * @see         java.awt.TextComponent#getText  
     */
    public void setText(String t) {
        super.setText(t);

	// This could change the preferred size of the Component.
	if (valid) {
	    invalidate();
	}
    }

    /**
     * Indicates whether or not this text field has a
     * character set for echoing.
     * <p>
     * An echo character is useful for text fields where
     * user input should not be echoed to the screen, as in
     * the case of a text field for entering a password.
     * @return     <code>true</code> if this text field has
     *                 a character set for echoing;
     *                 <code>false</code> otherwise.
     * @see        java.awt.TextField#setEchoChar
     * @see        java.awt.TextField#getEchoChar
     */
    public boolean echoCharIsSet() {
	return echoChar != 0;
    }

    /**
     * Gets the number of columns in this text field. A column is an
     * approximate average character width that is platform-dependent.
     * @return     the number of columns.
     * @see        java.awt.TextField#setColumns
     * @since      JDK1.1
     */
    public int getColumns() {
	return columns;
    }

    /**
     * Sets the number of columns in this text field. A column is an 
     * approximate average character width that is platform-dependent.
     * @param      columns   the number of columns.
     * @see        java.awt.TextField#getColumns
     * @exception  IllegalArgumentException   if the value
     *                 supplied for <code>columns</code>
     *                 is less than <code>0</code>. 
     * @since      JDK1.1
     */
    public synchronized 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 preferred size of this text field
     * with the specified number of columns.
     * @param     columns the number of columns
     *                 in this text field.
     * @return    the preferred dimensions for
     *                 displaying this text field.
     * @since     JDK1.1
     */
    public Dimension getPreferredSize(int columns) {
    	return preferredSize(columns);
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>getPreferredSize(int)</code>.
     */
    public Dimension preferredSize(int columns) {
        synchronized (getTreeLock()) {
	    TextFieldPeer peer = (TextFieldPeer)this.peer;
	    return (peer != null) ?
		       peer.preferredSize(columns) :
		       super.preferredSize();
        }
    }

    /**
     * Gets the preferred size of this text field.
     * @return     the preferred dimensions for
     *                         displaying this text field.
     * @since      JDK1.1
     */
    public Dimension getPreferredSize() {
    	return preferredSize();
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>getPreferredSize()</code>.
     */
    public Dimension preferredSize() {
        synchronized (getTreeLock()) {
	    return (columns > 0) ?
		       preferredSize(columns) :
		       super.preferredSize();
        }
    }

    /**
     * Gets the minumum dimensions for a text field with
     * the specified number of columns.
     * @param    columns   the number of columns in
     *                          this text field.
     * @since    JDK1.1
     */
    public Dimension getMinimumSize(int columns) {
    	return minimumSize(columns);
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>getMinimumSize(int)</code>.
     */
    public Dimension minimumSize(int columns) {
        synchronized (getTreeLock()) {
	    TextFieldPeer peer = (TextFieldPeer)this.peer;
	    return (peer != null) ?
		       peer.minimumSize(columns) :
		       super.minimumSize();
        }
    }

    /**
     * Gets the minumum dimensions for this text field.
     * @return     the minimum dimensions for
     *                  displaying this text field.
     * @since      JDK1.1
     */
    public Dimension getMinimumSize() {
    	return minimumSize();
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>getMinimumSize()</code>.
     */
    public Dimension minimumSize() {
        synchronized (getTreeLock()) {
	    return (columns > 0) ?
		       minimumSize(columns) :
		       super.minimumSize();
        }
    }

    /**
     * Adds the specified action listener to receive
     * action events from this text field.  
     * If l is null, no exception is thrown and no action is performed.
     *
     * @param      l the action listener.
     * @see        java.awt.event#ActionListener
     * @see        java.awt.TextField#removeActionListener
     * @since      JDK1.1
     */
    public synchronized void addActionListener(ActionListener l) {
	if (l == null) {
	    return;
	}
	actionListener = AWTEventMulticaster.add(actionListener, l);
        newEventsOnly = true;
    }

    /**
     * Removes the specified action listener so that it no longer
     * receives action events from this text field.
     * If l is null, no exception is thrown and no action is performed.
     *
     * @param      	l the action listener.
     * @see        	java.awt.event#ActionListener
     * @see        	java.awt.TextField#addActionListener
     * @since      	JDK1.1
     */
    public synchronized void removeActionListener(ActionListener l) {
	if (l == null) {
	    return;
	}
	actionListener = AWTEventMulticaster.remove(actionListener, l);
    }

    /**
     * Return an array of all the listeners that were added to the TextField
     * with addXXXListener(), where XXX is the name of the <code>listenerType</code>
     * argument.  For example, to get all of the ActionListener(s) for the
     * given TextField <code>t</code>, one would write:
     * <pre>
     * ActionListener[] als = (ActionListener[])(t.getListeners(ActionListener.class))
     * </pre>
     * If no such listener list exists, then an empty array is returned.
     * 
     * @param    listenerType   Type of listeners requested
     * @return	 all of the listeners of the specified type supported by this text field
     * @since 1.3
     */
    public EventListener[] getListeners(Class listenerType) { 
	EventListener l = null; 
	if  (listenerType == ActionListener.class) { 
	    l = actionListener;
	} else {
	    return super.getListeners(listenerType);
	}
	return AWTEventMulticaster.getListeners(l, listenerType);
    }

    // REMIND: remove when filtering is done at lower level
    boolean eventEnabled(AWTEvent e) {
        if (e.id == ActionEvent.ACTION_PERFORMED) {
            if ((eventMask & AWTEvent.ACTION_EVENT_MASK) != 0 ||
                actionListener != null) {
                return true;
            }
            return false;
        }
        return super.eventEnabled(e);
    }

    /**
     * Processes events on this text field. If the event
     * is an instance of <code>ActionEvent</code>,
     * it invokes the <code>processActionEvent</code>
     * method. Otherwise, it invokes <code>processEvent</code>
     * on the superclass.
     * @param      e the event.
     * @see        java.awt.event.ActionEvent
     * @see        java.awt.TextField#processActionEvent
     * @since      JDK1.1
     */
    protected void processEvent(AWTEvent e) {
        if (e instanceof ActionEvent) {
            processActionEvent((ActionEvent)e);
            return;
        }
	super.processEvent(e);
    }

    /**
     * Processes action events occurring on this text field by
     * dispatching them to any registered
     * <code>ActionListener</code> objects.
     * <p>
     * This method is not called unless action events are
     * enabled for this component. Action events are enabled
     * when one of the following occurs:
     * <p><ul>
     * <li>An <code>ActionListener</code> object is registered
     * via <code>addActionListener</code>.
     * <li>Action events are enabled via <code>enableEvents</code>.
     * </ul>
     * @param       e the action event.
     * @see         java.awt.event.ActionListener
     * @see         java.awt.TextField#addActionListener
     * @see         java.awt.Component#enableEvents
     * @since       JDK1.1
     */
    protected void processActionEvent(ActionEvent e) {
        if (actionListener != null) {
            actionListener.actionPerformed(e);
        }
    }

    /**
     * Returns the parameter string representing the state of this
     * text field. This string is useful for debugging.
     * @return      the parameter string of this text field.
     */
    protected String paramString() {
	String str = super.paramString();
	if (echoChar != 0) {
	    str += ",echo=" + echoChar;
	}
	return str;
    }


    /* 
     * Serialization support.  
     */
    /**
     * The textField Serialized Data Version.
     *
     * @serial
     */
    private int textFieldSerializedDataVersion = 1;

    /**
     * Writes default serializable fields to stream.  Writes
     * a list of serializable ActionListener(s) as optional data.
     * The non-serializable ActionListener(s) are detected and
     * no attempt is made to serialize them.
     *
     * @serialData Null terminated sequence of zero or more pairs.
     *             A pair consists of a String and Object.
     *             The String indicates the type of object and
     *             is one of the following :
     *             ActionListenerK indicating and ActionListener object.
     *
     * @see AWTEventMulticaster.save(ObjectOutputStream, String, EventListener)
     * @see java.awt.Component.actionListenerK
     */
    private void writeObject(ObjectOutputStream s)
      throws IOException
    {
        s.defaultWriteObject();

        AWTEventMulticaster.save(s, actionListenerK, actionListener);
        s.writeObject(null);
    }

    /**
     * Read the ObjectInputStream and if it isn't null, 
     * add a listener to receive action events fired by the 
     * TextField.  Unrecognized keys or values will be 
     * ignored.
     * 
     * @see removeActionListener()
     * @see addActionListener()
     */
    private void readObject(ObjectInputStream s)
      throws ClassNotFoundException, IOException
    {
        s.defaultReadObject();

        // Make sure the state we just read in for columns has legal values
        if (columns < 0) {
            columns = 0;
        }

        // Read in listeners, if any
        Object keyOrNull;
        while(null != (keyOrNull = s.readObject())) {
	    String key = ((String)keyOrNull).intern();

	    if (actionListenerK == key) {
                addActionListener((ActionListener)(s.readObject()));
            } else { 
                // skip value for unrecognized key
                s.readObject();
            }
        }
    }


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


    /**
     * Gets the AccessibleContext associated with this TextField. 
     * For text fields, the AccessibleContext takes the form of an 
     * AccessibleAWTTextField. 
     * A new AccessibleAWTTextField instance is created if necessary.
     *
     * @return an AccessibleAWTTextField that serves as the 
     *         AccessibleContext of this TextField
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleAWTTextField();
        }
        return accessibleContext;
    }

    /**
     * This class implements accessibility support for the 
     * <code>TextField</code> class.  It provides an implementation of the 
     * Java Accessibility API appropriate to text field user-interface elements.
     */
    protected class AccessibleAWTTextField extends AccessibleAWTTextComponent {

        /**
         * 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;
        }
    }

}