/*
 * Copyright (C) 2017-2022 Sebastiano Vigna
 *
 * 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 it.unimi.dsi.fastutil;

import static org.junit.Assert.assertTrue;

import java.util.Random;

import org.junit.Test;

import it.unimi.dsi.fastutil.ints.IntArrays;
import it.unimi.dsi.fastutil.ints.IntArraysTest;

public class ArraysTest {


	private static void testMergeSort(final int x[]) {
		testMergeSort(x, 0, x.length);
	}

	private static void testMergeSort(final int x[], final int from, final int to) {
		Arrays.mergeSort(from, to, (k1, k2) -> Integer.compare(x[k1], x[k2]), (k1, k2) -> {
			final int t = x[k1];
			x[k1] = x[k2];
			x[k2] = t;
		});
		for(int i = to - 1; i-- != from;) assertTrue(x[i] <= x[i + 1]);
	}

	@Test
	public void testMergeSort() {
		testMergeSort(new int[] { 2, 1, 0, 4 });
		testMergeSort(new int[] { 2, -1, 0, -4 });
		testMergeSort(IntArrays.shuffle(IntArraysTest.identity(100), new Random(0)));

		int[] t = new int[100];
		Random random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testMergeSort(t);
		t = new int[100000];
		random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testMergeSort(t);
		for(int i = 100; i-- != 10;) t[i] = random.nextInt();
		testMergeSort(t, 10, 100);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt() & 0xF;
		testMergeSort(t);

		t = new int[10000000];
		random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testMergeSort(t);
	}

	private static void testQuickSort(final int x[]) {
		testQuickSort(x, 0, x.length);
	}

	private static void testQuickSort(final int x[], final int from, final int to) {
		Arrays.quickSort(from, to, (k1, k2) -> Integer.compare(x[k1], x[k2]), (k1, k2) -> {
			final int t = x[k1];
			x[k1] = x[k2];
			x[k2] = t;
		});
		for(int i = to - 1; i-- != from;) assertTrue(x[i] <= x[i + 1]);
	}

	@Test
	public void testQuickSort() {
		testQuickSort(new int[] { 2, 1, 0, 4 });
		testQuickSort(new int[] { 2, -1, 0, -4 });
		testQuickSort(IntArrays.shuffle(IntArraysTest.identity(100), new Random(0)));

		int[] t = new int[100];
		Random random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testQuickSort(t);
		t = new int[100000];
		random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testQuickSort(t);
		for(int i = 100; i-- != 10;) t[i] = random.nextInt();
		testQuickSort(t, 10, 100);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt() & 0xF;
		testQuickSort(t);

		t = new int[10000000];
		random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testQuickSort(t);
	}

	private static void testParallelQuickSort(final int x[]) {
		testParallelQuickSort(x, 0, x.length);
	}

	private static void testParallelQuickSort(final int x[], final int from, final int to) {
		Arrays.parallelQuickSort(from, to, (k1, k2) -> Integer.compare(x[k1], x[k2]), (k1, k2) -> {
			final int t = x[k1];
			x[k1] = x[k2];
			x[k2] = t;
		});
		for(int i = to - 1; i-- != from;) assertTrue(x[i] <= x[i + 1]);
	}

	@Test
	public void testParallelQuickSort() {
		testParallelQuickSort(new int[] { 2, 1, 0, 4 });
		testParallelQuickSort(new int[] { 2, -1, 0, -4 });
		testParallelQuickSort(IntArrays.shuffle(IntArraysTest.identity(100), new Random(0)));

		int[] t = new int[100];
		Random random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testParallelQuickSort(t);
		t = new int[100000];
		random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testParallelQuickSort(t);
		for(int i = 100; i-- != 10;) t[i] = random.nextInt();
		testParallelQuickSort(t, 10, 100);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt() & 0xF;
		testParallelQuickSort(t);

		t = new int[10000000];
		random = new Random(0);
		for(int i = t.length; i-- != 0;) t[i] = random.nextInt();
		testParallelQuickSort(t);
	}

	@Test(expected = ArrayIndexOutOfBoundsException.class)
	public void testEnsureOffSetLength() {
		Arrays.ensureOffsetLength(42, Integer.MAX_VALUE, 10);
	}
}