/*
    * 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.LocalizedCoreFormats;
  import org.hipparchus.exception.MathIllegalArgumentException;
  import org.hipparchus.exception.MathIllegalStateException;
  import org.hipparchus.util.FastMath;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.Test;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  
  
  /**
   * Unit tests for the {@link RootsOfUnity} class.
   *
   */
  class RootsOfUnityTest {
  
      @Test
      void testMathIllegalState1() {
          assertThrows(MathIllegalStateException.class, () -> {
              final RootsOfUnity roots = new RootsOfUnity();
              roots.getReal(0);
          });
      }
  
      @Test
      void testMathIllegalState2() {
          assertThrows(MathIllegalStateException.class, () -> {
              final RootsOfUnity roots = new RootsOfUnity();
              roots.getImaginary(0);
          });
      }
  
      @Test
      void testMathIllegalState3() {
          assertThrows(MathIllegalStateException.class, () -> {
              final RootsOfUnity roots = new RootsOfUnity();
              roots.isCounterClockWise();
          });
      }
  
      @Test
      void testZeroNumberOfRoots() {
          assertThrows(MathIllegalArgumentException.class, () -> {
              final RootsOfUnity roots = new RootsOfUnity();
              roots.computeRoots(0);
          });
      }
  
      @Test
      void testGetNumberOfRoots() {
          final RootsOfUnity roots = new RootsOfUnity();
          assertEquals(0, roots.getNumberOfRoots(), "");
          roots.computeRoots(5);
          assertEquals(5, roots.getNumberOfRoots(), "");
          /*
           * Testing -5 right after 5 is important, as the roots in this case are
           * not recomputed.
           */
          roots.computeRoots(-5);
          assertEquals(5, roots.getNumberOfRoots(), "");
          roots.computeRoots(6);
          assertEquals(6, roots.getNumberOfRoots(), "");
      }
  
      @Test
      public void testErrorConditions() {
          final RootsOfUnity roots = new RootsOfUnity();
          roots.computeRoots(5);
          try {
              roots.getReal(-2);
              Assertions.fail("an exception should have been thrown");
          } catch (MathIllegalArgumentException e) {
              assertEquals(LocalizedCoreFormats.OUT_OF_RANGE_ROOT_OF_UNITY_INDEX,
                           e.getSpecifier());
              assertEquals(-2, e.getParts()[0]);
             assertEquals( 0, e.getParts()[1]);
             assertEquals( 4, e.getParts()[2]);
         }
         try {
             roots.getImaginary(-2);
             Assertions.fail("an exception should have been thrown");
         } catch (MathIllegalArgumentException e) {
             assertEquals(LocalizedCoreFormats.OUT_OF_RANGE_ROOT_OF_UNITY_INDEX,
                          e.getSpecifier());
             assertEquals(-2, e.getParts()[0]);
             assertEquals( 0, e.getParts()[1]);
             assertEquals( 4, e.getParts()[2]);
         }
         try {
             roots.getReal(5);
             Assertions.fail("an exception should have been thrown");
         } catch (MathIllegalArgumentException e) {
             assertEquals(LocalizedCoreFormats.OUT_OF_RANGE_ROOT_OF_UNITY_INDEX,
                          e.getSpecifier());
             assertEquals( 5, e.getParts()[0]);
             assertEquals( 0, e.getParts()[1]);
             assertEquals( 4, e.getParts()[2]);
         }
         try {
             roots.getImaginary(5);
             Assertions.fail("an exception should have been thrown");
         } catch (MathIllegalArgumentException e) {
             assertEquals(LocalizedCoreFormats.OUT_OF_RANGE_ROOT_OF_UNITY_INDEX,
                          e.getSpecifier());
             assertEquals( 5, e.getParts()[0]);
             assertEquals( 0, e.getParts()[1]);
             assertEquals( 4, e.getParts()[2]);
         }
     }
 
     @Test
     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);
             assertEquals(FastMath.cos(t), roots.getReal(k), tol, msg);
             assertEquals(FastMath.sin(t), roots.getImaginary(k), tol, msg);
         }
     }
 }