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/**
 * The MIT License
 *
 * Copyright (C) 2015 Asterios Raptis
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
 * associated documentation files (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
 * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package de.alpharogroup.comparators;

/**
 * The class {@link ComparatorExtensions} have helper methods for comparators.
 */
public final class ComparatorExtensions
{
	/**
	 * Compares the given objects and returns the int value.
	 *
	 * @param 
	 *            the generic type
	 * @param object
	 *            the object
	 * @param compareWithObject
	 *            the object to compare with.
	 * @return the int
	 */
	public static > int compare(final T object, final T compareWithObject)
	{
		final Integer nullCheck = ComparatorExtensions.nullCheck(object, compareWithObject);
		if (nullCheck != null)
		{
			return nullCheck;
		}
		// Null check completed so we can compare the objects
		return object.compareTo(compareWithObject);
	}

	/**
	 * Compares the given objects and returns the int value.
	 *
	 * @param 
	 *            the generic type
	 * @param object
	 *            the object
	 * @param compareWithObject
	 *            the object to compare with.
	 * @param sortOrder
	 *            the sort order
	 * @return the int
	 */
	public static > int compare(final T object, final T compareWithObject,
		final SortOrder sortOrder)
	{
		if (SortOrder.DESCENDING.equals(sortOrder))
		{
			return compare(object, compareWithObject) * (-1);
		}
		return compare(object, compareWithObject);

	}

	/**
	 * Null check of the given objects that is intended for use in equals method. Returns the
	 * appropriate boolean or null if given objects are ready for equation.
	 *
	 * @param 
	 *            the generic type
	 * @param object
	 *            the object
	 * @param compareWithObject
	 *            the compare with object
	 * @return the boolean or null if both are not null.
	 */
	public static  Boolean equalNullCheck(final T object, final T compareWithObject)
	{
		if (object == compareWithObject)
		{
			return true;
		}
		if (object == null || compareWithObject == null)
		{
			return false;
		}
		return null;
	}

	/**
	 * Checks if one of the given objects are null and returns the value for the Comparator or null
	 * if both are not null or if the given objects are not the same Object.
	 *
	 * @param 
	 *            the generic type
	 * @param object
	 *            the object
	 * @param compareWithObject
	 *            the compare with object
	 * @return the integer or null if both are not null or if the given objects are not the same
	 *         Object.
	 */
	public static  Integer nullCheck(final T object, final T compareWithObject)
	{
		return nullCheck(object, compareWithObject, false);
	}

	/**
	 * Checks if one of the given objects are null and returns the value for the Comparator or null
	 * if both are not null or if the given objects are not the same Object.
	 *
	 * @param 
	 *            the generic type
	 * @param object
	 *            the object
	 * @param compareWithObject
	 *            the compare with object
	 * @param nullIsGreaterThan
	 *            the flag that says if null objects are greater
	 * @return the integer or null if both are not null or if the given objects are not the same
	 *         Object.
	 */
	public static  Integer nullCheck(final T object, final T compareWithObject,
		final boolean nullIsGreaterThan)
	{
		if (object == compareWithObject)
		{
			return 0;// it is the same Object
		}
		if (object == null)
		{
			if (nullIsGreaterThan)
			{
				return 1;
			}
			return -1; // object is null so its smaller
		}
		// Check if one of the objects are null
		if (compareWithObject == null)
		{
			if (nullIsGreaterThan)
			{
				return -1;
			}
			return 1;// compareWithObject is null so its bigger
		}
		return null;
	}

	private ComparatorExtensions()
	{
	}

}