/* $Id$ */
package org.noreply.fancydress.misc;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Date;
import java.util.TimeZone;

/**
 * This class implements some functionality needed all over the place.
 */
public class Util {
	/**
	 * return the octets of this String (US-ASCII encoding)
	 *
	 * @param m String to convert to the octet array
	 * @return octet array
	 */
	public static byte[] toOctets (String m) {
		byte[] result;
		try {
			result = m.getBytes("US-ASCII");
		} catch (IOException e) {
			throw new Error(e);
		}
		return(result);
	}

	/**
	 * return a base16 or hex representation of an octet array
	 *
	 * @param buf octet array
	 * @return the octet array in hex
	 */
	public static String asHex(byte buf[]) {
		StringBuffer strbuf = new StringBuffer(buf.length * 3);
		int i;

		for (i = 0; i < buf.length; i++) {
			if (((int) buf[i] & 0xff) < 0x10)
				strbuf.append("0");

			strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
			strbuf.append(" ");
		}
		return strbuf.toString();
	}

	/**
	 * Read an octet array from a hex encoding.
	 *
	 * Read an octet array from a hex encoding, ignoring all whitespace.
	 *
	 * @param s hex encoded octet array
	 * @param octet array
	 */
	public static byte[] fromHex(String s) {
		boolean gotone = false;
		String r = "";
		ArrayList a = new ArrayList();
		
		for (int i=0; i < s.length(); i++) {
			char c = s.charAt(i);
			if (Character.isWhitespace(c))
				continue;
			r = r + c;
			if (gotone) {
				a.add(Integer.valueOf(r, 16));
				r = "";
			}
			gotone = !gotone;
		}

		byte[] result = new byte[a.size()];
		for (int i=0; i<result.length; i++) {
			Integer o = (Integer) a.get(i);
			int val = o.intValue();
			result[i] = (byte) val;
		};
		return(result);
	}

	/**
	 * Return the smaller one of a and b.
	 *
	 * @param a
	 * @param b
	 * @return a&lt;b ? a : b
	 */
	public static int min(int a, int b) {
		return a<b ? a : b;
	}

	/**
	 * Return the greater one of a and b.
	 *
	 * @param a
	 * @param b
	 * @return a&gt;b ? a : b
	 */
	public static int max(int a, int b) {
		return a>b ? a : b;
	}

	/**
	 * Check if two octet arrays are equal
	 *
	 * @param a
	 * @param b
	 * @return true if a is equal to b
	 */
	public static boolean equal(byte[] a, byte[] b) {
		boolean result = true;
		if (a.length != b.length)
			return(false);
		for (int i=0; i<a.length; i++)
			result = result && (a[i] == b[i]);
		return(result);
	};

	/**
	 * Concatinate two octet arrays
	 *
	 * @param a a
	 * @param b b
	 * @return a + b
	 */
	public static byte[] concat(byte[] a, byte[] b) {
		byte[] result = new byte[ a.length + b.length ];
		for (int i=0; i<a.length; i++)
			result[i] = a[i];
		for (int i=0; i<b.length; i++)
			result[a.length + i] = b[i];
		return(result);
	}

	/**
	 * Return a substring of an octet array
	 *
	 * @param a an octet array
	 * @param s starting position
	 * @param len length to copy
	 * @return the slice of <code>a</code> starting at <code>s</code> of <code>len</code> octets in length
	 */
	public static byte[] slice(byte[] a, int s, int len) {
		byte[] result = new byte[len];
		System.arraycopy(a, s, result, 0, len);
		return(result);
	}

	/* FIXME: switch to singleton so we need not generate the formats every time */
	/**
	 * Parse an ISO date yyyy-MM-dd.
	 *
	 * @param s a string holding a date
	 * @return Date the date represented in <code>s</code>
	 * @throws ParseException if <code>s</code> is not a valid date of that format
	 */
	public static Date parseDate(String s) {
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
		format.setTimeZone(TimeZone.getTimeZone("GMT"));
		format.setLenient(false);
		try {
			return format.parse(s);
		} catch (ParseException e) {
			/* FIXME: US date.. */
			format = new SimpleDateFormat("yyyy/MM/dd");
			format.setTimeZone(TimeZone.getTimeZone("GMT"));
			format.setLenient(false);
			try {
				return format.parse(s);
			} catch (ParseException e2) {
				return null;
			}
		}
	}
	/**
	 * Parse an ISO date yyyy-MM-dd HH:mm:ss.
	 *
	 * @param s a string holding a date
	 * @return Date the date represented in <code>s</code>
	 * @throws ParseException if <code>s</code> is not a valid date of that format
	 */
	public static Date parseDateTime(String s) {
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		format.setTimeZone(TimeZone.getTimeZone("GMT"));
		format.setLenient(false);
		try {
			return format.parse(s);
		} catch (ParseException e) {
			/* FIXME: US date.. */
			format = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
			format.setTimeZone(TimeZone.getTimeZone("GMT"));
			format.setLenient(false);
			try {
				return format.parse(s);
			} catch (ParseException e2) {
				return null;
			}
		}
	}
	/**
	 * Parse an ISO date yyyy-MM-dd HH:mm:ss.SSSS.
	 *
	 * @param s a string holding a date
	 * @return Date the date represented in <code>s</code>
	 * @throws ParseException if <code>s</code> is not a valid date of that format
	 */
	public static Date parseDateTimeMS(String s) {
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSS");
		format.setTimeZone(TimeZone.getTimeZone("GMT"));
		format.setLenient(false);
		try {
			return format.parse(s);
		} catch (ParseException e) {
			return null;
		}
	}
	/**
	 * Parse a boolean (yes/no) value.
	 *
	 * @param s a string, either "yes" or "no"
	 * @return true if <code>s</code> is "yes", false if it is "no"
	 * @throws ParseException if <code>s</code> is neither "yes" or "no"
	 */
	public static boolean parseBoolean(String s) throws ParseException {
		if (s.equals("yes"))
			return true;
		else if (s.equals("no"))
			return false;
		else {
			throw new ParseException("Cannot parse boolean expression "+s,0);
		}
	}

	/**
	 * Tokenize comma separated lists into single tokens.
	 *
	 * Single tokens are trimmed of whitespace.
	 *
	 * @param s string of comma separated items.
	 * @param separator a token separator
	 * @return an array of single tokens.
	 */
	public static String[] tokenize(String s, char separator) {
		ArrayList list = new ArrayList();
		int indexFrom = 0;
		int indexOf;

		do {
			indexOf = s.indexOf(separator, indexFrom);
			String v = (indexOf >= 0) ?
				s.substring(indexFrom, indexOf).trim() :
				s.substring(indexFrom).trim();
			list.add( v );
			indexFrom = indexOf + 1;
		} while (indexOf >= 0);

		return (String[]) list.toArray(new String[list.size()]);
	}
}