Copyright (c) 2005, 2008 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
/*******************************************************************************
 * Copyright (c) 2005, 2008 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.core.internal.content;

import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import org.eclipse.core.runtime.content.IContentDescription;

public class Util {
	public static String[] parseItems(String string) {
		return parseItems(string, ","); //$NON-NLS-1$
	}

	public static String[] parseItems(String string, String separator) {
		if (string == null)
			return new String[0];
		StringTokenizer tokenizer = new StringTokenizer(string, separator, true);
		if (!tokenizer.hasMoreTokens())
			return new String[] {string.trim()};
		String first = tokenizer.nextToken().trim();
		boolean wasSeparator = false;
		if (first.equals(separator)) {
			// leading separator
			first = ""; //$NON-NLS-1$
			wasSeparator = true;
		}
		// simple cases, do not create temporary list
		if (!tokenizer.hasMoreTokens())
			return wasSeparator ? /* two empty strings */new String[] {first, first} : /*single non-empty element  */new String[] {first};
		ArrayList<String> items = new ArrayList<>();
		items.add(first);
		String current;
		do {
			current = tokenizer.nextToken().trim();
			boolean isSeparator = current.equals(separator);
			if (isSeparator) {
				if (wasSeparator)
					items.add(""); //$NON-NLS-1$
			} else
				items.add(current);
			wasSeparator = isSeparator;
		} while (tokenizer.hasMoreTokens());
		if (wasSeparator)
			// trailing separator
			items.add(""); //$NON-NLS-1$
		return items.toArray(new String[items.size()]);
	}

	public static List<String> parseItemsIntoList(String string) {
		return parseItemsIntoList(string, ","); //$NON-NLS-1$
	}

	public static List<String> parseItemsIntoList(String string, String separator) {
		List<String> items = new ArrayList<>(5);
		if (string == null)
			return items;
		StringTokenizer tokenizer = new StringTokenizer(string, separator, true);
		if (!tokenizer.hasMoreTokens()) {
			items.add(string.trim());
			return items;
		}
		String first = tokenizer.nextToken().trim();
		boolean wasSeparator = false;
		if (first.equals(separator)) {
			// leading separator
			first = ""; //$NON-NLS-1$
			wasSeparator = true;
		}
		items.add(first);
		if (!tokenizer.hasMoreTokens())
			return items;
		String current;
		do {
			current = tokenizer.nextToken().trim();
			boolean isSeparator = current.equals(separator);
			if (isSeparator) {
				if (wasSeparator)
					items.add(""); //$NON-NLS-1$
			} else
				items.add(current);
			wasSeparator = isSeparator;
		} while (tokenizer.hasMoreTokens());
		if (wasSeparator)
			// trailing separator
			items.add(""); //$NON-NLS-1$
		return items;
	}

	public static String toListString(Object[] list) {
		return toListString(list, ","); //$NON-NLS-1$
	}

	public static String toListString(Object[] list, String separator) {
		if (list == null || list.length == 0)
			return null;
		StringBuilder result = new StringBuilder();
		for (Object element : list) {
			result.append(element);
			result.append(separator);
		}
		// ignore last comma
		return result.substring(0, result.length() - 1);
	}

	/*
	 * Reads bom from the stream. Note that the stream will not be repositioned
	 * when the method returns.
	 */
	public static byte[] getByteOrderMark(InputStream input) throws IOException {
		int first = input.read();
		switch (first) {
		case 0xEF:
			//look for the UTF-8 Byte Order Mark (BOM)
			int second = input.read();
			int third = input.read();
			if (second == 0xBB && third == 0xBF)
				return IContentDescription.BOM_UTF_8;
			break;
		case 0xFE:
			//look for the UTF-16 BOM
			if (input.read() == 0xFF)
				return IContentDescription.BOM_UTF_16BE;
			break;
		case 0xFF:
			if (input.read() == 0xFE)
				return IContentDescription.BOM_UTF_16LE;
			break;
		default:
			break;
		}
		return null;
	}
}