/*
    * 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
    *
    *      https://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.
   */
  
  /*
   * This is not the original file distributed by the Apache Software Foundation
   * It has been modified by the Hipparchus project
   */
  package org.hipparchus.complex;
  
  import org.hipparchus.exception.MathIllegalArgumentException;
  import org.hipparchus.exception.MathIllegalStateException;
  import org.hipparchus.util.FastMath;
  import org.junit.Assert;
  import org.junit.Test;
  
  
  /**
   * Unit tests for the {@link RootsOfUnity} class.
   *
   */
  public class RootsOfUnityTest {
  
      @Test(expected = MathIllegalStateException.class)
      public void testMathIllegalState1() {
          final RootsOfUnity roots = new RootsOfUnity();
          roots.getReal(0);
      }
  
      @Test(expected = MathIllegalStateException.class)
      public void testMathIllegalState2() {
          final RootsOfUnity roots = new RootsOfUnity();
          roots.getImaginary(0);
      }
  
      @Test(expected = MathIllegalStateException.class)
      public void testMathIllegalState3() {
          final RootsOfUnity roots = new RootsOfUnity();
          roots.isCounterClockWise();
      }
  
      @Test(expected = MathIllegalArgumentException.class)
      public void testZeroNumberOfRoots() {
          final RootsOfUnity roots = new RootsOfUnity();
          roots.computeRoots(0);
      }
  
      @Test
      public void testGetNumberOfRoots() {
          final RootsOfUnity roots = new RootsOfUnity();
          Assert.assertEquals("", 0, roots.getNumberOfRoots());
          roots.computeRoots(5);
          Assert.assertEquals("", 5, roots.getNumberOfRoots());
          /*
           * Testing -5 right after 5 is important, as the roots in this case are
           * not recomputed.
           */
          roots.computeRoots(-5);
          Assert.assertEquals("", 5, roots.getNumberOfRoots());
          roots.computeRoots(6);
          Assert.assertEquals("", 6, roots.getNumberOfRoots());
      }
  
      @Test
      public void testComputeRoots() {
          final RootsOfUnity roots = new RootsOfUnity();
          for (int n = -10; n < 11; n++) {
              /*
               * Testing -n right after n is important, as the roots in this case
               * are not recomputed.
               */
              if (n != 0) {
                  roots.computeRoots(n);
                  doTestComputeRoots(roots);
                  roots.computeRoots(-n);
                  doTestComputeRoots(roots);
              }
          }
      }
  
      private void doTestComputeRoots(final RootsOfUnity roots) {
          final int n = roots.isCounterClockWise() ? roots.getNumberOfRoots() :
              -roots.getNumberOfRoots();
          final double tol = 10 * Math.ulp(1.0);
          for (int k = 0; k < n; k++) {
              final double t = 2.0 * FastMath.PI * k / n;
             final String msg = String.format("n = %d, k = %d", n, k);
             Assert.assertEquals(msg, FastMath.cos(t), roots.getReal(k), tol);
             Assert.assertEquals(msg, FastMath.sin(t), roots.getImaginary(k), tol);
         }
     }
 }