/*
 * Copyright 2007 JBoss Inc
 *
 * 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.
 *
 * Created on Dec 6, 2007
 */
package org.drools.util;

import java.text.DateFormatSymbols;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

/**
 * @author etirelli
 *
 */
public class DateUtils {

	private static final long serialVersionUID = 400L;
	private static final String DEFAULT_FORMAT_MASK = "dd-MMM-yyyy";
	private static final String DATE_FORMAT_MASK = getDateFormatMask();
	private static final String DEFAULT_COUNTRY = Locale.getDefault()
			.getCountry();
	private static final String DEFINE_COUNTRY = getDefaultContry();
	private static final String DEFAULT_LANGUAGE = Locale.getDefault()
			.getLanguage();
	private static final String DEFINE_LANGUAGE = getDefaultLanguage();

	private static ThreadLocal<SimpleDateFormat> df = new ThreadLocal<SimpleDateFormat>() {
		protected SimpleDateFormat initialValue() {
			DateFormatSymbols dateSymbol = new DateFormatSymbols(new Locale(
					DEFINE_LANGUAGE, DEFINE_COUNTRY));
			SimpleDateFormat dateFormat = new SimpleDateFormat(
					DATE_FORMAT_MASK, dateSymbol);
			return dateFormat;
		};
	};

	private static String getDefaultLanguage() {
		String fmt = System.getProperty("drools.defaultlanguage");
		if (fmt == null) {
			fmt = DEFAULT_LANGUAGE;
		}
		return fmt;
	}

	private static String getDefaultContry() {
		String fmt = System.getProperty("drools.defaultcountry");
		if (fmt == null) {
			fmt = DEFAULT_COUNTRY;
		}
		return fmt;
	}

	/** Use the simple date formatter to read the date from a string */
	public static Date parseDate(final String input) {
		try {
			return df.get().parse(input);
		} catch (final ParseException e) {
			throw new IllegalArgumentException("Invalid date input format: ["
					+ input + "] it should follow: [" + DATE_FORMAT_MASK + "]");
		}
	}

	/** Converts the right hand side date as appropriate */
	public static Date getRightDate(final Object object2) {
		if (object2 == null) {
			return null;
		}
		if (object2 instanceof String) {
			return parseDate((String) object2);
		} else if (object2 instanceof Date) {
			return (Date) object2;
		} else {
			throw new IllegalArgumentException("Unable to convert "
					+ object2.getClass() + " to a Date.");
		}
	}

	/** Check for the system property override, if it exists */
	public static String getDateFormatMask() {
		String fmt = System.getProperty("drools.dateformat");
		if (fmt == null) {
			fmt = DEFAULT_FORMAT_MASK;
		}
		return fmt;
	}
}
