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/***********************************************************************************************************************
 *
 * 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.test.testdata;

import java.io.BufferedReader;
import java.io.IOException;
import java.util.Random;
import java.util.regex.Pattern;

import org.junit.Assert;


public class ConnectedComponentsData {

	public static final String getEnumeratingVertices(int num) {
		if (num < 1 || num > 1000000) {
			throw new IllegalArgumentException();
		}

		StringBuilder bld = new StringBuilder(3 * num);
		for (int i = 1; i <= num; i++) {
			bld.append(i);
			bld.append('\n');
		}
		return bld.toString();
	}

	/**
	 * Creates random edges such that even numbered vertices are connected with even numbered vertices
	 * and odd numbered vertices only with other odd numbered ones.
	 * 
	 * @param numEdges
	 * @param numVertices
	 * @param seed
	 * @return
	 */
	public static final String getRandomOddEvenEdges(int numEdges, int numVertices, long seed) {
		if (numVertices < 2 || numVertices > 1000000 || numEdges < numVertices || numEdges > 1000000) {
			throw new IllegalArgumentException();
		}

		StringBuilder bld = new StringBuilder(5 * numEdges);

		// first create the linear edge sequence even -> even and odd -> odd to make sure they are
		// all in the same component
		for (int i = 3; i <= numVertices; i++) {
			bld.append(i - 2).append(' ').append(i).append('\n');
		}

		numEdges -= numVertices - 2;
		Random r = new Random(seed);

		for (int i = 1; i <= numEdges; i++) {
			int evenOdd = r.nextBoolean() ? 1 : 0;

			int source = r.nextInt(numVertices) + 1;
			if (source % 2 != evenOdd) {
				source--;
				if (source < 1) {
					source = 2;
				}
			}

			int target = r.nextInt(numVertices) + 1;
			if (target % 2 != evenOdd) {
				target--;
				if (target < 1) {
					target = 2;
				}
			}

			bld.append(source).append(' ').append(target).append('\n');
		}
		return bld.toString();
	}

	public static void checkOddEvenResult(BufferedReader result) throws IOException {
		Pattern split = Pattern.compile(" ");
		String line;
		while ((line = result.readLine()) != null) {
			String[] res = split.split(line);
			Assert.assertEquals("Malformed result: Wrong number of tokens in line.", 2, res.length);
			try {
				int vertex = Integer.parseInt(res[0]);
				int component = Integer.parseInt(res[1]);

				int should = vertex % 2;
				if (should == 0) {
					should = 2;
				}
				Assert.assertEquals("Vertex is in wrong component.", should, component);
			} catch (NumberFormatException e) {
				Assert.fail("Malformed result.");
			}
		}
	}

	private ConnectedComponentsData() {}
}