/***********************************************************************************************************************
 * Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
 *
 * 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.
 **********************************************************************************************************************/

package eu.stratosphere.compiler.util;

import java.util.Arrays;

import eu.stratosphere.api.common.operators.Order;
import eu.stratosphere.api.common.operators.Ordering;
import eu.stratosphere.api.common.operators.util.FieldList;
import eu.stratosphere.api.common.operators.util.FieldSet;
import eu.stratosphere.compiler.CompilerException;


/**
 * 
 */
public class Utils
{
	public static final FieldList createOrderedFromSet(FieldSet set) {
		if (set instanceof FieldList) {
			return (FieldList) set;
		} else {
			final int[] cols = set.toArray();
			Arrays.sort(cols);
			return new FieldList(cols);
		}
	}
	
	public static final Ordering createOrdering(FieldList fields, boolean[] directions) {
		final Ordering o = new Ordering();
		for (int i = 0; i < fields.size(); i++) {
			o.appendOrdering(fields.get(i), null, directions == null || directions[i] ? Order.ASCENDING : Order.DESCENDING);
		}
		return o;
	}
	
	public static final Ordering createOrdering(FieldList fields) {
		final Ordering o = new Ordering();
		for (int i = 0; i < fields.size(); i++) {
			o.appendOrdering(fields.get(i), null, Order.ANY);
		}
		return o;
	}
	
	public static boolean[] getDirections(Ordering o, int numFields) {
		final boolean[] dirs = o.getFieldSortDirections();
		if (dirs.length == numFields) {
			return dirs;
		} else if (dirs.length > numFields) {
			final boolean[] subSet = new boolean[numFields];
			System.arraycopy(dirs, 0, subSet, 0, numFields);
			return subSet;
		} else {
			throw new CompilerException();
		}
	}
	
	// --------------------------------------------------------------------------------------------
	
	/**
	 * No instantiation.
	 */
	private Utils() {}
}