/*******************************************************************************
 * Copyright (c) 2000, 2012 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.dnd;

import org.eclipse.swt.internal.ole.win32.*;
import org.eclipse.swt.internal.win32.*;

/**
 * The class <code>RTFTransfer</code> provides a platform specific mechanism
 * for converting text in RTF format 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 RTF text is shown
 * below:</p>
 *
 * <code><pre>
 *     String rtfData = "{\\rtf1{\\colortbl;\\red255\\green0\\blue0;}\\uc1\\b\\i Hello World}";
 * </code></pre>
 *
 * @see Transfer
 */
public class RTFTransfer extends ByteArrayTransfer {

	private static RTFTransfer _instance = new RTFTransfer();
	private static final String CF_RTF = "Rich Text Format"; //$NON-NLS-1$
	private static final int CF_RTFID = registerType(CF_RTF);

private RTFTransfer() {}

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

/**
 * This implementation of <code>javaToNative</code> converts RTF-formatted text
 * represented by a java <code>String</code> to a platform specific representation.
 *
 * @param object a java <code>String</code> containing RTF 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
 */
@Override
public void javaToNative (Object object, TransferData transferData){
	if (!checkRTF(object) || !isSupportedType(transferData)) {
		DND.error(DND.ERROR_INVALID_DATA);
	}
	// CF_RTF is stored as a null terminated byte array
	String string = (String)object;
	int count = string.length();
	char[] chars = new char[count + 1];
	string.getChars(0, count, chars, 0);
	int codePage = OS.GetACP();
	int cchMultiByte = OS.WideCharToMultiByte(codePage, 0, chars, -1, null, 0, null, null);
	if (cchMultiByte == 0) {
		transferData.stgmedium = new STGMEDIUM();
		transferData.result = COM.DV_E_STGMEDIUM;
		return;
	}
	long /*int*/ lpMultiByteStr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, cchMultiByte);
	OS.WideCharToMultiByte(codePage, 0, chars, -1, lpMultiByteStr, cchMultiByte, null, null);
	transferData.stgmedium = new STGMEDIUM();
	transferData.stgmedium.tymed = COM.TYMED_HGLOBAL;
	transferData.stgmedium.unionField = lpMultiByteStr;
	transferData.stgmedium.pUnkForRelease = 0;
	transferData.result = COM.S_OK;
	return;
}

/**
 * This implementation of <code>nativeToJava</code> converts a platform specific
 * representation of RTF 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 RTF text if the conversion was successful;
 * 		otherwise null
 *
 * @see Transfer#javaToNative
 */
@Override
public Object nativeToJava(TransferData transferData){
	if (!isSupportedType(transferData) || transferData.pIDataObject == 0) return null;
	IDataObject data = new IDataObject(transferData.pIDataObject);
	data.AddRef();
	STGMEDIUM stgmedium = new STGMEDIUM();
	FORMATETC formatetc = transferData.formatetc;
	stgmedium.tymed = COM.TYMED_HGLOBAL;
	transferData.result = getData(data, formatetc, stgmedium);
	data.Release();
	if (transferData.result != COM.S_OK) return null;
	long /*int*/ hMem = stgmedium.unionField;
	try {
		long /*int*/ lpMultiByteStr = OS.GlobalLock(hMem);
		if (lpMultiByteStr == 0) return null;
		try {
			int codePage = OS.GetACP();
			int cchWideChar  = OS.MultiByteToWideChar (codePage, OS.MB_PRECOMPOSED, lpMultiByteStr, -1, null, 0);
			if (cchWideChar == 0) return null;
			char[] lpWideCharStr = new char [cchWideChar - 1];
			OS.MultiByteToWideChar (codePage, OS.MB_PRECOMPOSED, lpMultiByteStr, -1, lpWideCharStr, lpWideCharStr.length);
			return new String(lpWideCharStr);
		} finally {
			OS.GlobalUnlock(hMem);
		}
	} finally {
		OS.GlobalFree(hMem);
	}
}

@Override
protected int[] getTypeIds(){
	return new int[] {CF_RTFID};
}

@Override
protected String[] getTypeNames(){
	return new String[] {CF_RTF};
}

boolean checkRTF(Object object) {
	return (object != null  && object instanceof String && ((String)object).length() > 0);
}

@Override
protected boolean validate(Object object) {
	return checkRTF(object);
}
}