Utils.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * 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
 */
package org.openhab.binding.maxcube.internal;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Date;

/**
 * Utility class for common tasks within the MAX!Cube binding package.
 * 
 * @author Andreas Heil (info@aheil.de)
 * @since 1.4.0
 */
public final class Utils {

    /**
     * Returns the integer value of an hexadecimal number (base 16).
     * 
     * @param hex
     *            the hex value to be parsed into an integer
     * @return the given hex value as integer
     */
    public static final int fromHex(String hex) {
        return Integer.parseInt(hex, 16);
    }

    /**
     * Returns the hexadecimal number of a number of integer values.
     * 
     * @param values
     *            the integer values to be converted into hexadecimal numbers
     * @return the given numbers as hexadecimal number
     */
    public static final String toHex(int... values) {
        String returnValue = "";
        for (int v : values) {
            returnValue += v < 16 ? "0" + Integer.toHexString(v).toUpperCase() : Integer.toHexString(v).toUpperCase();
        }
        return returnValue;
    }

    /**
     * Returns the hexadecimal number of a bit array .
     * 
     * @param bits
     *            the boolean array representing the bits to be converted into hexadecimal numbers
     * @return the hexadecimal number
     */
    public static final String toHex(boolean[] bits) {
        int retVal = 0;
        for (int i = 0; i < bits.length; ++i) {
            retVal |= (bits[i] ? 1 : 0) << i;
        }
        return toHex(retVal);
    }

    /**
     * Converts an Java signed byte into its general (unsigned) value as being used in other programming languages and
     * platforms.
     * 
     * @param b
     *            the byte to be converted into its integer value
     * @return the integer value represented by the given byte
     */
    public static final int fromByte(byte b) {
        return b & 0xFF;
    }

    /**
     * Resolves the date and time based based on a three byte encoded within a MAX!Cube L message.
     *
     * Date decoding (two byte)
     * 
     * <pre>
     * Hex     Binary
     * 9D0B    1001110100001011
     *   MMMDDDDDM YYYYYY
     *   100     0        = 1000b  = 8d  = month
     *      11101         = 11101b = 29d = day
     *             001011 = 1011b  = 11d = year-2000
     * </pre>
     * 
     * Time decoding (one byte)
     * 
     * <pre>
     * Hex     Decimal
     * 1F      31 * 0.5 hours = 15:30
     * </pre>
     * 
     * @param date
     *            the date to be converted based on two bytes
     * @param time
     *            the time to be converted based on a single byte
     * @return the date time based on the values provided
     */
    @SuppressWarnings("deprecation")
    public static Date resolveDateTime(int date, int time) {

        int month = ((date & 0xE000) >> 12) + ((date & 0x80) >> 7);
        int day = (date & 0x1F00) >> 8;
        int year = (date & 0x0F) + 2000;

        int hours = (int) (time * 0.5);
        int minutes = (int) (60 * ((time * 0.5) - hours));

        return new Date(year, month, day, hours, minutes);
    }

    /**
     * Returns a bit representation as boolean values in a reversed manner.
     * A bit string <code>0001 0010</code> would be returnd as <code>0100 1000</code>.
     * That way, the least significant bit can be addressed by bits[0], the second by bits[1] and so on.
     *
     * @param value
     *            the integer value to be converted in a bit array
     * @return
     *         the bit array of the input value in a reversed manner.
     */
    public static boolean[] getBits(int value) {

        boolean[] bits = new boolean[8];

        for (int i = 0; i < 8; i++) {
            bits[i] = (((value >> i) & 0x1) == 1);
        }

        return bits;
    }

    /**
     * Convert a string representation of hexadecimal to a byte array.
     * 
     * For example:
     * String s = "00010203"
     * returned byte array is {0x00, 0x01, 0x03}
     *
     * @param s
     * @return byte array equivalent to hex string
     **/
    public static byte[] hexStringToByteArray(String s) {

        int len = s.length();
        byte[] data = new byte[len / 2];

        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i + 1), 16));
        }

        return data;
    }

    /**
     * Convert a byte array to a string representation of hexadecimals.
     * 
     * For example:
     * byte array is {0x00, 0x01, 0x03}
     * returned String s = "00 01 02 03"
     *
     * @param byte array
     * @return String equivalent to hex string
     **/
    static final String HEXES = "0123456789ABCDEF";

    public static String getHex(byte[] raw) {
        if (raw == null) {
            return null;
        }
        final StringBuilder hex = new StringBuilder(3 * raw.length);
        for (final byte b : raw) {
            hex.append(HEXES.charAt((b & 0xF0) >> 4)).append(HEXES.charAt((b & 0x0F))).append(" ");
        }
        hex.delete(hex.length() - 1, hex.length());
        return hex.toString();
    }

    /**
     * Retrieves the stacktrace of an exception as string.
     * 
     * @param e
     *            the exception to resolve the stacktrace from
     * @return
     *         the stacktrace from the exception provided
     */
    public static String getStackTrace(Exception e) {
        StringWriter stringWriter = new StringWriter();
        PrintWriter printWriter = new PrintWriter(stringWriter);
        e.printStackTrace(printWriter);
        return stringWriter.toString();
    }
}