/*
    * 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.
   */
  package org.hipparchus.linear;
  
  import org.hipparchus.analysis.UnivariateFunction;
  import org.hipparchus.analysis.function.Sin;
  import org.hipparchus.exception.MathRuntimeException;
  import org.hipparchus.linear.RealVector.Entry;
  import org.hipparchus.util.FastMath;
  import org.junit.jupiter.api.Test;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Random;
  import java.util.Set;
  
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  /**
   * This is an abstract test of the {@link
   * RealVector#unmodifiableRealVector(RealVector) unmodifiable vector}
   * implementation. These unmodifiable vectors decorate a (modifiable)
   * {@link RealVector}; therefore, a new implementation of this abstract
   * test should be considered for each implementation of
   * {@link RealVector}.
   *
   *
   */
  public abstract class UnmodifiableRealVectorAbstractTest {
      /** The dimension of the randomly generated vectors. */
      protected static final int DIM = 100;
      /** Absolute tolerance. */
      protected static final double EPS = 10 * Math.ulp(1d);
      /**
       * The list of methods which are excluded from the general test
       * {@link #testAllButExcluded()}.
       */
      protected static final Set<String> EXCLUDE = new HashSet<String>();
      /** The random number generator (always initialized with the same seed. */
      protected static final Random RANDOM;
  
      static {
          EXCLUDE.add("getEntry");
          EXCLUDE.add("setEntry");
          EXCLUDE.add("addToEntry");
          EXCLUDE.add("getSubVector");
          EXCLUDE.add("setSubVector");
          EXCLUDE.add("iterator");
          EXCLUDE.add("sparseIterator");
          EXCLUDE.add("walkInDefaultOrder");
          EXCLUDE.add("walkInOptimizedOrder");
          EXCLUDE.add("ebeDivide");
          EXCLUDE.add("ebeMultiply");
  
          // Excluded because they are inherited from "Object".
          for (Method m : Object.class.getMethods()) {
              EXCLUDE.add(m.getName());
          }
          RANDOM = new Random(20110813);
      }
  
      /**
       * Returns {@code true} if the specified {@code double} are equal (within a
       * given tolerance).
       *
       * @param x First {@code double}.
       * @param y Second {@code double}.
       * @return {@code true} if {@code x} and {@code y} are equal.
       */
      public static boolean equals(final double x, final double y) {
          if (x == y) {
              return true;
          } else if (FastMath.abs(x) <= EPS) {
              return FastMath.abs(y) <= EPS;
          } else if (FastMath.abs(y) <= EPS) {
              return FastMath.abs(x) <= EPS;
          } else {
              return FastMath.abs(x - y) <= EPS * FastMath.min(FastMath.abs(x), FastMath.abs(y));
          }
      }
  
     /**
      * Returns {@code true} if the specified {@code double} arrays are equal
      * (within a given tolerance).
      *
      * @param x First array.
      * @param y Second array.
      * @return {@code true} if {@code x} and {@code y} are equal.
      */
     public static boolean equals(final double[] x, final double[] y) {
         if (x.length != y.length) {
             return false;
         }
         final int n = x.length;
         for (int i = 0; i < n; i++) {
             if (!equals(x[i], y[i])) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Returns {@code true} if the specified {@code RealVector} are equal
      * (within a given tolerance).
      *
      * @param x First vector.
      * @param y Second vector.
      * @return {@code true} if {@code x} and {@code y} are equal.
      */
     public static boolean equals(final RealVector x, final RealVector y) {
         if (x.getDimension() != y.getDimension()) {
             return false;
         }
         final int n = x.getDimension();
         for (int i = 0; i < n; i++) {
             if (!equals(x.getEntry(i), y.getEntry(i))) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Returns {@code true} if the specified {@code RealVector} is equal to the
      * specified {@code double} array (within a given tolerance).
      *
      * @param x Vector.
      * @param y Array.
      * @return {@code true} if {@code x} and {@code y} are equal.
      */
     public static boolean equals(final RealVector x, final double[] y) {
         if (x.getDimension() != y.length) {
             return false;
         }
         final int n = x.getDimension();
         for (int i = 0; i < n; i++) {
             if (!equals(x.getEntry(i), y[i])) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Returns {@code true} if the specified {@code RealMatrix} are equal
      * (within a given tolerance).
      *
      * @param x First matrix.
      * @param y Second matrix.
      * @return {@code true} if {@code x} and {@code y} are equal.
      */
     public static boolean equals(final RealMatrix x, final RealMatrix y) {
         if (x.getRowDimension() != y.getRowDimension()) {
             return false;
         }
         if (x.getColumnDimension() != y.getColumnDimension()) {
             return false;
         }
         final int rows = x.getRowDimension();
         final int cols = x.getColumnDimension();
         for (int i = 0; i < rows; i++) {
             for (int j = 0; j < cols; j++) {
                 if (!equals(x.getEntry(i, j), y.getEntry(i, j))) {
                     return false;
                 }
             }
         }
         return true;
     }
 
     /**
      * Returns {@code true} if the specified {@code Object} are equal.
      *
      * @param x First object.
      * @param y Second object.
      * @return {@code true} if {@code x} and {@code y} are equal.
      * @throws IllegalArgumentException if {@code x} and {@code y} could
      * not be compared.
      */
     public static boolean equals(final Object x, final Object y) {
         if (x instanceof Boolean) {
             if (y instanceof Boolean) {
                 return ((Boolean) x).booleanValue() == ((Boolean) y)
                         .booleanValue();
             } else {
                 return false;
             }
         }
         if (x instanceof Integer) {
             if (y instanceof Integer) {
                 return ((Integer) x).intValue() == ((Integer) y).intValue();
             } else {
                 return false;
             }
         } else if (x instanceof Double) {
             if (y instanceof Double) {
                 return equals(((Double) x).doubleValue(),
                         ((Double) y).doubleValue());
             } else {
                 return false;
             }
         } else if (x instanceof double[]) {
             if (y instanceof double[]) {
                 return equals((double[]) x, (double[]) y);
             } else if (y instanceof RealVector) {
                 return equals((RealVector) y, (double[]) x);
             } else {
                 return false;
             }
         } else if (x instanceof RealVector) {
             if (y instanceof double[]) {
                 return equals((RealVector) x, (double[]) y);
             } else if (y instanceof RealVector) {
                 return equals((RealVector) x, (RealVector) y);
             } else {
                 return false;
             }
         } else if (x instanceof RealMatrix) {
             if (y instanceof RealMatrix) {
                 return equals((RealMatrix) x, (RealMatrix) y);
             } else {
                 return false;
             }
         } else {
             throw new IllegalArgumentException("could not compare " + x + ", "
                     + y);
         }
     }
 
     /**
      * Creates a new random vector of a specified type. This vector is then to
      * be wrapped in an unmodifiable vector.
      *
      * @return a new random vector.
      */
     public abstract RealVector createVector();
 
     /**
      * Creates a new random object of the specified type.
      *
      * @param c Class of the object to be created.
      * @return a new random object.
      * @throws IllegalArgumentException if the specified class is not
      * recognized by this method.
      */
     public Object createParameter(final Class<?> c) {
         if (c == Integer.TYPE) {
             return Integer.valueOf(RANDOM.nextInt());
         } else if (c == Double.TYPE) {
             return Double.valueOf(RANDOM.nextDouble());
         } else if (c == double[].class) {
             final double[] v = new double[DIM];
             for (int i = 0; i < DIM; i++) {
                 v[i] = RANDOM.nextDouble();
             }
             return v;
         } else if (c.isAssignableFrom(RealVector.class)) {
             return createVector();
         } else if (c.isAssignableFrom(UnivariateFunction.class)) {
             return new Sin();
         } else {
             throw new IllegalArgumentException("could not create " + c);
         }
     }
 
     /**
      * This is the general test of most methods in the
      * {@link RealVector#unmodifiableRealVector(RealVector) unmodifiable vector}.
      * It works as follows.
      * First, an unmodifiable view of a copy of the specified random vector
      * {@code u} is created: this defines {@code v}. Then the <em>same</em>
      * method {@code m} is invoked on {@code u} and {@code v}, with randomly
      * generated parameters {@code args}.
      * If it turns out that {@code u} has changed after the call of method
      * {@code m}, then this test checks that the call of this method on
      * {@code v} resulted in a {@link MathRuntimeException}. If
      * {@code u} was not modified, then this test checks that the results
      * returned by the call of method {@code m} on {@code u} and {@code v}
      * returned the same result.
      *
      * @param m Method to be tested.
      * @param u Random vector from which the unmodifiable view is to be
      *constructed.
      * @param args Arguments to be passed to method {@code m}.
      */
     private void callMethod(final Method m,
                             final RealVector u,
                             final Object... args)
         throws IllegalAccessException,
                IllegalArgumentException,
                InvocationTargetException {
         final RealVector uu = u.copy();
         final RealVector v = RealVector.unmodifiableRealVector(u.copy());
         Object exp = m.invoke(u, args);
         if (equals(uu, u)) {
             Object act = m.invoke(v, args);
             assertTrue(equals(uu, v),
                               m.toGenericString() + ", unmodifiable vector has changed");
             assertTrue(equals(exp, act),
                               m.toGenericString() + ", wrong result");
 
         } else {
             boolean flag = false;
             try {
                 m.invoke(v, args);
             } catch (InvocationTargetException e) {
                 if (e.getCause() instanceof MathRuntimeException) {
                     flag = true;
                 }
             }
             assertTrue(flag, m.toGenericString()+", exception should have been thrown");
         }
     }
 
     /**
      * This test calls {@link #callMethod(Method, RealVector, Object...)} on
      * every method defined in interface {@link RealVector}. It generates the
      * appropriate random arguments. Some methods are manually excluded (see
      * {@link #EXCLUDE}), they must be handled by separate tests.
      */
     @Test
     public void testAllButExcluded()
         throws IllegalAccessException,
                IllegalArgumentException,
                InvocationTargetException {
         Method[] method = RealVector.class.getMethods();
         for (int i = 0; i < method.length; i++) {
             Method m = method[i];
             if (!EXCLUDE.contains(m.getName())) {
                 RealVector u = (RealVector) createParameter(RealVector.class);
                 Class<?>[] paramType = m.getParameterTypes();
                 Object[] param = new Object[paramType.length];
                 for (int j = 0; j < paramType.length; j++) {
                     param[j] = createParameter(paramType[j]);
                 }
                 callMethod(m, u, param);
             }
         }
     }
 
     @Test
     public void testGetEntry() {
         RealVector u = createVector();
         RealVector v = RealVector.unmodifiableRealVector(u);
         for (int i = 0; i < DIM; i++) {
             assertTrue(equals(u.getEntry(i), v.getEntry(i)));
         }
     }
 
     @Test
     public void testSetEntry() {
         assertThrows(MathRuntimeException.class, () -> {
             RealVector u = createVector();
             RealVector v = RealVector.unmodifiableRealVector(u);
             for (int i = 0; i < DIM; i++) {
                 v.setEntry(i, 0d);
             }
         });
     }
 
     @Test
     public void testAddToEntry() {
         assertThrows(MathRuntimeException.class, () -> {
             RealVector u = createVector();
             RealVector v = RealVector.unmodifiableRealVector(u);
             for (int i = 0; i < DIM; i++) {
                 v.addToEntry(i, 0d);
             }
         });
     }
 
     @Test
     public void testGetSubVector() {
         RealVector u = createVector();
         RealVector v = RealVector.unmodifiableRealVector(u);
         for (int i = 0; i < DIM; i++) {
             for (int n = 1; n < DIM - i; n++) {
                 RealVector exp = u.getSubVector(i, n);
                 RealVector act = v.getSubVector(i, n);
                 assertTrue(equals(exp, act));
             }
         }
     }
 
     @Test
     public void testSetSubVector() {
         assertThrows(MathRuntimeException.class, () -> {
             RealVector u = createVector();
             RealVector v = RealVector.unmodifiableRealVector(u);
             v.setSubVector(0, new ArrayRealVector());
         });
     }
 
     @Test
     public void testIterator() {
         RealVector u = createVector();
         Iterator<Entry> i = u.iterator();
         RealVector v = RealVector.unmodifiableRealVector(u.copy());
         Iterator<Entry> j = v.iterator();
         boolean flag;
         while (i.hasNext()) {
             assertTrue(j.hasNext());
             Entry exp = i.next();
             Entry act = j.next();
             assertTrue(equals(exp.getIndex(), act.getIndex()));
             assertTrue(equals(exp.getValue(), act.getValue()));
             exp.setIndex(RANDOM.nextInt(DIM));
             act.setIndex(RANDOM.nextInt(DIM));
             flag = false;
             try {
                 act.setValue(RANDOM.nextDouble());
             } catch (MathRuntimeException e) {
                 flag = true;
             }
             assertTrue(flag, "exception should have been thrown");
         }
         assertFalse(j.hasNext());
     }
 
     @Test
     public void testSparseIterator() {
         RealVector u = createVector();
         Iterator<Entry> i = u.sparseIterator();
         RealVector v = RealVector.unmodifiableRealVector(u.copy());
         Iterator<Entry> j = v.sparseIterator();
         boolean flag;
         while (i.hasNext()) {
             assertTrue(j.hasNext());
             Entry exp = i.next();
             Entry act = j.next();
             assertTrue(equals(exp.getIndex(), act.getIndex()));
             assertTrue(equals(exp.getValue(), act.getValue()));
             exp.setIndex(RANDOM.nextInt(DIM));
             act.setIndex(RANDOM.nextInt(DIM));
             flag = false;
             try {
                 act.setValue(RANDOM.nextDouble());
             } catch (MathRuntimeException e) {
                 flag = true;
             }
             assertTrue(flag, "exception should have been thrown");
         }
         assertFalse(j.hasNext());
     }
 }