package de.tudarmstadt.informatik.hostage.commons;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.SecureRandom;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.Environment;
import android.text.TextUtils;

/**
 * Helper class with some static methods for general usage.
 * 
 * @author Lars Pandikow
 * @author Wulf Pfeiffer
 * 
 */
public final class HelperUtils {

	/**
	 * Converts a byte array into a hexadecimal String, e.g. {0x00, 0x01} to
	 * "00, 01".
	 * 
	 * @param bytes
	 *            that will be converted.
	 * @return converted String.
	 */
	public static String bytesToHexString(byte[] bytes) {
		char[] hexArray = "0123456789ABCDEF".toCharArray();
		int v;
		StringBuffer buffer = new StringBuffer();
		for (int j = 0; j < bytes.length; j++) {
			v = bytes[j] & 0xFF;
			buffer.append(hexArray[v >>> 4]);
			buffer.append(hexArray[v & 0x0F]);
			if (j < bytes.length - 1)
				buffer.append(", ");
		}
		return buffer.toString();
	}

	/**
	 * Converts a byte[] to a String, but only characters in ASCII between 32
	 * and 127
	 * 
	 * @param bytes
	 *            that are converted
	 * @return converted String
	 */
	public static String byteToStr(byte[] bytes) {
		int size = 0;
		for(byte b : bytes) {
			 if(isLetter((char) b)) {
				 size++;
			 }
		}
		char[] chars = new char[size];
		for (int i = 0, j = 0; i < bytes.length && j < size; i++) {
			if (isLetter((char) bytes[i])) {
				chars[j] = (char) bytes[i];
				j++;
			}
		}
		return new String(chars);
	}

	/**
	 * Concatenates several byte arrays.
	 * 
	 * @param bytes
	 *            The byte arrays.
	 * @return A single byte arrays containing all the bytes from the given
	 *         arrays in the order they are given.
	 */
	public static byte[] concat(byte[]... bytes) {
		int newSize = 0;
		for (byte[] b : bytes)
			if (b != null)
				newSize += b.length;
		byte[] dst = new byte[newSize];

		int currentPos = 0;
		int newPos;
		for (byte[] b : bytes) {
			if (b != null) {
				newPos = b.length;
				System.arraycopy(b, 0, dst, currentPos, newPos);
				currentPos += newPos;
			}
		}
		return dst;
	}

	/**
	 * Puts a 0x00 byte between each byte in a byte array.
	 * 
	 * @param bytes
	 *            that need to be filled with 0x00.
	 * @return filled byte array.
	 */
	public static byte[] fillWithZero(byte[] bytes) {
		byte[] newBytes = new byte[(bytes.length * 2)];
		for (int i = 0, j = 0; i < bytes.length && j < newBytes.length; i++, j = j + 2) {
			newBytes[j] = bytes[i];
			newBytes[j + 1] = 0x00;
		}
		return newBytes;
	}

	/**
	 * Puts a 0x00 byte between each byte and another 2 0x00 bytes at the end of
	 * a byte array.
	 * 
	 * @param bytes
	 *            that need to be filled with 0x00.
	 * @return filled byte array.
	 */
	public static byte[] fillWithZeroExtended(byte[] bytes) {
		byte[] zeroBytes = fillWithZero(bytes);
		byte[] newBytes = new byte[zeroBytes.length + 2];
		newBytes = HelperUtils.concat(zeroBytes, new byte[] { 0x00, 0x00 });
		return newBytes;
	}

	/**
	 * Gets BSSID of the wireless network.
	 * 
	 * @param context
	 *            Needs a context to get system recourses.
	 * @return BSSID of wireless network if connected, else null.
	 */
	public static String getBSSID(Context context) {
		String bssid = null;
		ConnectivityManager connManager = (ConnectivityManager) context
				.getSystemService(Context.CONNECTIVITY_SERVICE);
		NetworkInfo networkInfo = connManager
				.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
		if (networkInfo != null && networkInfo.isConnected()) {
			final WifiManager wifiManager = (WifiManager) context
					.getSystemService(Context.WIFI_SERVICE);
			final WifiInfo connectionInfo = wifiManager.getConnectionInfo();
			if (connectionInfo != null
					&& !TextUtils.isEmpty(connectionInfo.getSSID())) {
				bssid = connectionInfo.getBSSID();
			}
		}
		return bssid;
	}

	/**
	 * Gets internal IP address of the device in a wireless network.
	 * 
	 * @param context
	 *            Needs a context to get system recourses.
	 * @return internal IP of the device in a wireless network if connected,
	 *         else null.
	 */
	public static String getInternalIP(Context context) {
		String ipAddress = null;
		ConnectivityManager connManager = (ConnectivityManager) context
				.getSystemService(Context.CONNECTIVITY_SERVICE);
		NetworkInfo networkInfo = connManager
				.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
		if (networkInfo != null && networkInfo.isConnected()) {
			final WifiManager wifiManager = (WifiManager) context
					.getSystemService(Context.WIFI_SERVICE);
			final WifiInfo connectionInfo = wifiManager.getConnectionInfo();
			if (connectionInfo != null) {
				try {
					ipAddress = InetAddress.getByAddress(
							unpackInetAddress(connectionInfo.getIpAddress()))
							.getHostAddress();
				} catch (UnknownHostException e) {
					e.printStackTrace();
				}
			}
		}
		return ipAddress;
	}

	/**
	 * Gets SSID of the wireless network.
	 * 
	 * @param context
	 *            Needs a context to get system recourses
	 * @return SSID of wireless network if connected, else null.
	 */
	public static String getSSID(Context context) {
		String ssid = null;
		ConnectivityManager connManager = (ConnectivityManager) context
				.getSystemService(Context.CONNECTIVITY_SERVICE);
		NetworkInfo networkInfo = connManager
				.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
		if (networkInfo != null && networkInfo.isConnected()) {
			final WifiManager wifiManager = (WifiManager) context
					.getSystemService(Context.WIFI_SERVICE);
			final WifiInfo connectionInfo = wifiManager.getConnectionInfo();
			if (connectionInfo != null
					&& !TextUtils.isEmpty(connectionInfo.getSSID())) {
				ssid = connectionInfo.getSSID();
			}
		}
		return ssid;
	}
	
	/**
	 * Gets the mac address of the devicek.
	 * 
	 * @param context
	 *            Needs a context to get system recourses
	 * @return MAC address of the device.
	 */
	public static String getMacAdress(Context context) {
		String mac = null;
		WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
		WifiInfo connectionInfo = wifiManager.getConnectionInfo();		
		mac = connectionInfo.getMacAddress();
		return mac;
	}
	
	/**
	 * Produces a random String. The String can be of random length (minimum 1)
	 * with a maximum length, or it can be forced to have the length that was
	 * given.
	 * 
	 * @param length
	 *            maximal / forced length of String.
	 * @param forceLength
	 *            forces the String to be exact the given length instead of
	 *            maximum
	 * @return random String.
	 */
	public static String getRandomString(int length, boolean forceLength) {
		SecureRandom rndm = new SecureRandom();
		char[] c = new char[forceLength ? length : rndm.nextInt(length - 1) + 1];
		for (int i = 0; i < c.length; i++) {
			c[i] = (char) (rndm.nextInt(95) + 32);
		}
		return new String(c);
	}

	/**
	 * Converts a String into a byte array, e.g. "00, 01" to {0x00, 0x01}.
	 * 
	 * @param string
	 *            that will be converted.
	 * @return converted byte array.
	 */
	public static byte[] hexStringToBytes(String string) {
		String[] hexStrings = string.split(", ");
		byte[] bytes = new byte[hexStrings.length];
		for (int j = 0; j < hexStrings.length; j++) {
			bytes[j] = (byte) ((Character.digit(hexStrings[j].charAt(0), 16) << 4) + Character
					.digit(hexStrings[j].charAt(1), 16));
		}
		return bytes;
	}

	/**
	 * Checks if external storage is available for read and write.
	 * 
	 * @return True if external storage is available for read and write, else
	 *         false.
	 */
	public static boolean isExternalStorageWritable() {
		String state = Environment.getExternalStorageState();
		if (Environment.MEDIA_MOUNTED.equals(state)) {
			return true;
		}
		return false;
	}

	/**
	 * Generates a random byte[] of a specified size
	 * 
	 * @param size
	 *            of the byte[]
	 * @return random byte[]
	 */
	public static byte[] randomBytes(int size) {
		byte[] bytes = new byte[size];
		SecureRandom rdm = new SecureRandom();
		rdm.nextBytes(bytes);
		return bytes;
	}

	/**
	 * Turns around the values of an byte[], e.g. {0x00, 0x01, 0x02} turns into
	 * {0x02, 0x01, 0x00}.
	 * 
	 * @param bytes
	 *            array that is turned.
	 * @return turned array.
	 */
	public static byte[] turnByteArray(byte[] bytes) {
		byte[] tmp = new byte[bytes.length];
		for (int i = 0; i < bytes.length; i++) {
			tmp[i] = bytes[bytes.length - 1 - i];
		}
		return tmp;
	}

	/**
	 * Determines if a character is in ASCII between 32 and 126
	 * 
	 * @param character
	 *            that is checked
	 * @return true if the character is between 32 and 126, else false
	 */
	private static boolean isLetter(char character) {
		return (character > 31 && character < 127);
	}

	private static byte[] unpackInetAddress(int bytes) {
		return new byte[] { (byte) ((bytes) & 0xff),
				(byte) ((bytes >>> 8) & 0xff), (byte) ((bytes >>> 16) & 0xff),
				(byte) ((bytes >>> 24) & 0xff) };
	}
	
	public static boolean isWifiConnected(Context context){
		if(context == null) return false;
		ConnectivityManager connManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
		NetworkInfo mWifi = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);

		return mWifi.isConnected();
	}
}