/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
module dwt.dnd.TextTransfer;

import dwt.dwthelper.utils;

import dwt.internal.cocoa.NSString;
import dwt.internal.cocoa.OS;
 
/**
 * The class <code>TextTransfer</code> provides a platform specific mechanism 
 * for converting plain text represented as a java <code>String</code> 
 * to a platform specific representation of the data and vice versa.
 * 
 * <p>An example of a java <code>String</code> containing plain text is shown 
 * below:</p>
 * 
 * <code><pre>
 *     String textData = "Hello World";
 * </code></pre>
 * 
 * @see Transfer
 */
public class TextTransfer extends ByteArrayTransfer {

    static TextTransfer _instance = new TextTransfer();
    
    static final String ID_NAME = OS.NSStringPboardType.getString();
    static final int ID = registerType(ID_NAME);

TextTransfer() {}

/**
 * Returns the singleton instance of the TextTransfer class.
 *
 * @return the singleton instance of the TextTransfer class
 */
public static TextTransfer getInstance () {
    return _instance;
}

/**
 * This implementation of <code>javaToNative</code> converts plain text
 * represented by a java <code>String</code> to a platform specific representation.
 * 
 * @param object a java <code>String</code> containing text
 * @param transferData an empty <code>TransferData</code> object that will
 *      be filled in on return with the platform specific format of the data
 *  
 * @see Transfer#nativeToJava
 */
public void javaToNative (Object object, TransferData transferData) {
    if (!checkText(object) || !isSupportedType(transferData)) {
        DND.error(DND.ERROR_INVALID_DATA);
    }
    transferData.data = NSString.stringWith((String) object);
}

/**
 * This implementation of <code>nativeToJava</code> converts a platform specific 
 * representation of plain text to a java <code>String</code>.
 * 
 * @param transferData the platform specific representation of the data to be converted
 * @return a java <code>String</code> containing text if the conversion was successful; otherwise null
 * 
 * @see Transfer#javaToNative
 */
public Object nativeToJava(TransferData transferData){
    if (!isSupportedType(transferData) || transferData.data is null) return null;
    NSString string = (NSString) transferData.data;
    return string.getString();
}

protected int[] getTypeIds() {
    return new int[] {ID};
}

protected String[] getTypeNames() {
    return new String[] {ID_NAME};
}

bool checkText(Object object) {
    return (object !is null && object instanceof String && ((String)object).length() > 0);
}
protected bool validate(Object object) {
    return checkText(object);
}
}