package com.sjtu.util;

import com.sjtu.Constants;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.i18n.LocaleContextHolder;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * Date Utility Class This is used to convert Strings to Dates and Timestamps
 * 
 * <p>
 * <a href="DateUtil.java.html"><i>View Source</i></a>
 * </p>
 * 
 * @author <a href="mailto:matt@raibledesigns.com">Matt Raible</a> Modified by
 *         <a href="mailto:dan@getrolling.com">Dan Kibler </a> to correct time
 *         pattern. Minutes should be mm not MM (MM is month).
 * @version $Revision: 1.2 $ $Date: 2007/12/11 05:45:22 $
 */
public class DateUtil {
	// ~ Static fields/initializers
	// =============================================

	private static Log log = LogFactory.getLog(DateUtil.class);
	private static String defaultDatePattern = null;
	private static String timePattern = "HH:mm";

	// ~ Methods
	// ================================================================

	/**
	 * Return default datePattern (MM/dd/yyyy)
	 * 
	 * @return a string representing the date pattern on the UI
	 */
	public static String getDatePattern() {
		Locale locale = LocaleContextHolder.getLocale();
		try {
			defaultDatePattern = ResourceBundle.getBundle(Constants.BUNDLE_KEY,
					locale).getString("date.format");
		} catch (MissingResourceException mse) {
			defaultDatePattern = "MM/dd/yyyy";
		}

		return defaultDatePattern;
	}

	public static String getDateTimePattern() {
		return DateUtil.getDatePattern() + " HH:mm:ss.S";
	}

	/**
	 * This method attempts to convert an Oracle-formatted date in the form
	 * dd-MMM-yyyy to mm/dd/yyyy.
	 * 
	 * @param aDate
	 *            date from database as a string
	 * @return formatted string for the ui
	 */
	public static final String getDate(Date aDate) {
		SimpleDateFormat df = null;
		String returnValue = "";

		if (aDate != null) {
			df = new SimpleDateFormat(getDatePattern());
			returnValue = df.format(aDate);
		}

		return (returnValue);
	}

	/**
	 * This method generates a string representation of a date/time in the
	 * format you specify on input
	 * 
	 * @param aMask
	 *            the date pattern the string is in
	 * @param strDate
	 *            a string representation of a date
	 * @return a converted Date object
	 * @see java.text.SimpleDateFormat
	 * @throws ParseException
	 */
	public static final Date convertStringToDate(String aMask, String strDate)
			throws ParseException {
		SimpleDateFormat df = null;
		Date date = null;
		df = new SimpleDateFormat(aMask);

		if (log.isDebugEnabled()) {
			log.debug("converting '" + strDate + "' to date with mask '"
					+ aMask + "'");
		}

		try {
			date = df.parse(strDate);
		} catch (ParseException pe) {
			// log.error("ParseException: " + pe);
			throw new ParseException(pe.getMessage(), pe.getErrorOffset());
		}

		return (date);
	}

	/**
	 * This method returns the current date time in the format: MM/dd/yyyy HH:MM
	 * a
	 * 
	 * @param theTime
	 *            the current time
	 * @return the current date/time
	 */
	public static String getTimeNow(Date theTime) {
		return getDateTime(timePattern, theTime);
	}

	/**
	 * This method returns the current date in the format: MM/dd/yyyy
	 * 
	 * @return the current date
	 * @throws ParseException
	 */
	public static Calendar getToday() throws ParseException {
		Date today = new Date();
		SimpleDateFormat df = new SimpleDateFormat(getDatePattern());

		// This seems like quite a hack (date -> string -> date),
		// but it works ;-)
		String todayAsString = df.format(today);
		Calendar cal = new GregorianCalendar();
		cal.setTime(convertStringToDate(todayAsString));

		return cal;
	}

	/**
	 * This method generates a string representation of a date's date/time in
	 * the format you specify on input
	 * 
	 * @param aMask
	 *            the date pattern the string is in
	 * @param aDate
	 *            a date object
	 * @return a formatted string representation of the date
	 * 
	 * @see java.text.SimpleDateFormat
	 */
	public static final String getDateTime(String aMask, Date aDate) {
		SimpleDateFormat df = null;
		String returnValue = "";

		if (aDate == null) {
			log.error("aDate is null!");
		} else {
			df = new SimpleDateFormat(aMask);
			returnValue = df.format(aDate);
		}

		return (returnValue);
	}

	/**
	 * This method generates a string representation of a date based on the
	 * System Property 'dateFormat' in the format you specify on input
	 * 
	 * @param aDate
	 *            A date to convert
	 * @return a string representation of the date
	 */
	public static final String convertDateToString(Date aDate) {
		return getDateTime(getDatePattern(), aDate);
	}

	/**
	 * This method converts a String to a date using the datePattern
	 * 
	 * @param strDate
	 *            the date to convert (in format MM/dd/yyyy)
	 * @return a date object
	 * 
	 * @throws ParseException
	 */
	public static Date convertStringToDate(String strDate)
			throws ParseException {
		Date aDate = null;

		try {
			if (log.isDebugEnabled()) {
				log.debug("converting date with pattern: " + getDatePattern());
			}

			aDate = convertStringToDate(getDatePattern(), strDate);
		} catch (ParseException pe) {
			log.error("Could not convert '" + strDate
					+ "' to a date, throwing exception");
			pe.printStackTrace();
			throw new ParseException(pe.getMessage(), pe.getErrorOffset());

		}

		return aDate;
	}
}