/*******************************************************************************
 * Copyright 2014 Rafael Garcia Moreno.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package com.bladecoder.engineeditor.common;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Properties;
import java.util.TreeSet;

/**
 * Overide Properties methods to allow the next features:
 * 
 * - The keys are written in order. 
 * - The timestamp comment is not writing when
 * saving the .properties
 * 
 * @author rgarcia
 */
@SuppressWarnings("serial")
public class OrderedProperties extends Properties {
	@Override
	public synchronized Enumeration<Object> keys() {
		return Collections.enumeration(new TreeSet<Object>(keySet()));
	}

	@Override
	public void store(Writer writer, String comments) throws IOException {
		store1((writer instanceof BufferedWriter) ? (BufferedWriter) writer : new BufferedWriter(writer), comments,
				false);
	}

	@Override
	public void store(OutputStream out, String comments) throws IOException {
		store1(new BufferedWriter(new OutputStreamWriter(out, "8859_1")), comments, true);
	}

	private void store1(BufferedWriter bw, String comments, boolean escUnicode) throws IOException {

		synchronized (this) {
			for (Enumeration<?> e = keys(); e.hasMoreElements();) {
				String key = (String) e.nextElement();
				String val = (String) get(key);
				key = saveConvert(key, true, escUnicode);
				/*
				 * No need to escape embedded and trailing spaces for value,
				 * hence pass false to flag.
				 */
				val = saveConvert(val, false, escUnicode);
				bw.write(key + "=" + val);
				bw.newLine();
			}
		}
		bw.flush();
	}

	/*
	 * Converts unicodes to encoded \uxxxx and escapes special characters
	 * with a preceding slash
	 */
	private String saveConvert(String theString, boolean escapeSpace, boolean escapeUnicode) {
		int len = theString.length();
		int bufLen = len * 2;
		if (bufLen < 0) {
			bufLen = Integer.MAX_VALUE;
		}
		StringBuffer outBuffer = new StringBuffer(bufLen);

		for (int x = 0; x < len; x++) {
			char aChar = theString.charAt(x);
			// Handle common case first, selecting largest block that
			// avoids the specials below
			if ((aChar > 61) && (aChar < 127)) {
				if (aChar == '\\') {
					outBuffer.append('\\');
					outBuffer.append('\\');
					continue;
				}
				outBuffer.append(aChar);
				continue;
			}
			switch (aChar) {
			case ' ':
				if (x == 0 || escapeSpace)
					outBuffer.append('\\');
				outBuffer.append(' ');
				break;
			case '\t':
				outBuffer.append('\\');
				outBuffer.append('t');
				break;
			case '\n':
				outBuffer.append('\\');
				outBuffer.append('n');
				break;
			case '\r':
				outBuffer.append('\\');
				outBuffer.append('r');
				break;
			case '\f':
				outBuffer.append('\\');
				outBuffer.append('f');
				break;
			case '=': // Fall through
			case ':': // Fall through
			case '#': // Fall through
//			case '!':
				outBuffer.append('\\');
				outBuffer.append(aChar);
				break;
			default:
				if (((aChar < 0x0020) || (aChar > 0x007e)) && escapeUnicode) {
					outBuffer.append('\\');
					outBuffer.append('u');
					outBuffer.append(toHex((aChar >> 12) & 0xF));
					outBuffer.append(toHex((aChar >> 8) & 0xF));
					outBuffer.append(toHex((aChar >> 4) & 0xF));
					outBuffer.append(toHex(aChar & 0xF));
				} else {
					outBuffer.append(aChar);
				}
			}
		}
		return outBuffer.toString();
	}

	/**
	 * Convert a nibble to a hex character
	 * 
	 * @param nibble
	 *            the nibble to convert.
	 */
	private static char toHex(int nibble) {
		return hexDigit[(nibble & 0xF)];
	}

	private static final char[] hexDigit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
			'F' };
}