/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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 org.apache.commons.rng.simple.internal;
  
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.util.Arrays;
  import java.util.concurrent.ThreadLocalRandom;
  import java.util.stream.IntStream;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.params.ParameterizedTest;
  import org.junit.jupiter.params.provider.MethodSource;
  
  /**
   * Tests the endian conversion of all array converters.
   */
  class ArrayConverterEndianTest {
      /**
       * Gets the lengths for the byte[] seeds.
       *
       * @return the lengths
       */
      static IntStream getLengths() {
          return IntStream.rangeClosed(0, 16);
      }
  
      @ParameterizedTest
      @MethodSource(value = {"getLengths"})
      void testLittleEndian(int bytes) {
          final byte[] seedBytes = new byte[bytes];
          ThreadLocalRandom.current().nextBytes(seedBytes);
  
          // Reference implementation using a ByteBuffer
          final ByteBuffer bb = ByteBuffer.wrap(
              Arrays.copyOf(seedBytes, Conversions.longSizeFromByteSize(bytes) * Long.BYTES))
              .order(ByteOrder.LITTLE_ENDIAN);
  
          // byte[] -> int[]
          final int[] expectedInt = new int[Conversions.intSizeFromByteSize(bytes)];
          for (int i = 0; i < expectedInt.length; i++) {
              expectedInt[i] = bb.getInt();
          }
          Assertions.assertArrayEquals(expectedInt, new ByteArray2IntArray().convert(seedBytes));
          Assertions.assertArrayEquals(expectedInt, (int[]) NativeSeedType.INT_ARRAY.convert(seedBytes, expectedInt.length));
  
          // byte[] -> long[]
          bb.clear();
          final long[] expectedLong = new long[Conversions.longSizeFromByteSize(bytes)];
          for (int i = 0; i < expectedLong.length; i++) {
              expectedLong[i] = bb.getLong();
          }
          Assertions.assertArrayEquals(expectedLong, new ByteArray2LongArray().convert(seedBytes));
          Assertions.assertArrayEquals(expectedLong, (long[]) NativeSeedType.LONG_ARRAY.convert(seedBytes, expectedLong.length));
  
          // int[] -> long[]
          Assertions.assertArrayEquals(expectedLong, new IntArray2LongArray().convert(expectedInt));
          Assertions.assertArrayEquals(expectedLong, (long[]) NativeSeedType.LONG_ARRAY.convert(expectedInt, expectedLong.length));
  
          // long[] -> int[]
          Assertions.assertArrayEquals(expectedInt, (int[]) NativeSeedType.INT_ARRAY.convert(expectedLong, expectedInt.length));
      }
  }