content: /*
   *  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.causeway.commons.internal.collections;
  
  import java.lang.reflect.Array;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Optional;
  import java.util.function.BiPredicate;
  import java.util.function.Function;
  import java.util.stream.Collector;
  
  import org.jspecify.annotations.Nullable;
  
  import org.springframework.util.ClassUtils;
  
  import org.apache.causeway.commons.internal._Constants;
  import org.apache.causeway.commons.internal.base._Casts;
  import org.apache.causeway.commons.internal.base._NullSafe;
  
  import org.jspecify.annotations.NonNull;
  import lombok.experimental.UtilityClass;
  
  /**
   * <h1>- internal use only -</h1>
   * <p>
   * Common Array idioms.
   * </p>
   * <p>
   * <b>WARNING</b>: Do <b>NOT</b> use any of the classes provided by this package! <br/>
   * These may be changed or removed without notice!
   * </p>
   *
   * @since 2.0
   */
  @UtilityClass
  public final class _Arrays {
  
      // -- PREDICATES
  
      /**
       * Whether given {@code test} predicate evaluates 'true' for any given pair of elements
       * {@code array1[index]} and {@code array2[index]}, with {@code index=[0..n-1]} and {@code n}
       * the number of elements of {@code array1/2}.
       * @param array1 - nullable
       * @param array2 - nullable
       * @param test - a predicate
       * @return whether there is any matching pair; false - if array1 and array2 are both empty
       * @throws IllegalArgumentException - if array lengths do not match
       * @throws NullPointerException - if {@code test} is null
       */
      public static <T> boolean testAnyMatch(
              final @Nullable T[] array1,
              final @Nullable T[] array2,
              final @NonNull BiPredicate<T, T> test) {
  
          final int s1 = _NullSafe.size(array1);
          final int s2 = _NullSafe.size(array2);
          if(s1!=s2) {
              throw new IllegalArgumentException("Array length missmatch");
          }
          if(s1==0) {
              return false;
          }
          for(int i=0; i<s1; ++i) {
              if(test.test(array1[i], array2[i])) {
                  return true;
              }
          }
          return false;
      }
  
      /**
       * Whether given {@code test} predicate evaluates 'true' for all given pairs of elements
       * {@code array1[index]} and {@code array2[index]}, with {@code index=[0..n-1]} and {@code n}
       * the number of elements of {@code array1/2}.
       * @param array1 - nullable
       * @param array2 - nullable
       * @param test - a predicate
       * @return whether all pairs match; true - if array1 and array2 are both empty
       * @throws IllegalArgumentException - if array lengths do not match
       * @throws NullPointerException - if {@code test} is null
       */
      public static <T> boolean testAllMatch(
              final @Nullable T[] array1,
              final @Nullable T[] array2,
              final @NonNull BiPredicate<T, T> test) {
          return !testAnyMatch(array1, array2, test.negate());
      }
  
      /**
       * @param cls
       * @return whether {@code cls} represents an array
       */
      public static boolean isArrayType(final @Nullable Class<?> cls) {
          return cls!=null ? cls.isArray() : false;
      }
  
      /**
       * For convenience also provided in {@link _Collections}.
       * @param cls
       * @return whether {@code cls} implements the java.util.Collection interface
       * or represents an array
       */
      public static boolean isCollectionOrArrayType(final Class<?> cls) {
          return _Collections.isCollectionType(cls) || _Arrays.isArrayType(cls);
      }
  
      // -- TO-ARRAY COLLECTORS
  
      /**
       * Known-size Collector.
       * @param componentType
       * @param length
       */
      public static <T> Collector<T,?,T[]> toArray(final @NonNull Class<T> componentType, final int length){
          return new _Arrays_Collector<T>(resolvePrimitiveIfNecessary(componentType), length);
      }
  
      /**
       * Unknown-size Collector.
       * @param componentType
       */
      public static <T> Collector<T,?,T[]> toArray(final @NonNull Class<T> componentType){
          return new _Arrays_CollectorUnknownSize<T>(resolvePrimitiveIfNecessary(componentType));
      }
  
      private static <T> Class<T> resolvePrimitiveIfNecessary(final Class<T> componentType) {
          var nonPrimitive = ClassUtils.resolvePrimitiveIfNecessary(componentType);
          return _Casts.uncheckedCast(nonPrimitive);
      }
  
      // -- CONCATENATION
  
      /**
       * Returns a new array containing all components {first, *rest}
       * @param first (non-null)
       * @param rest (nullable)
       * @return (non-null)
       * @exception  ArrayStoreException  if an element in the <code>src</code>
       *               array could not be stored into the <code>dest</code> array
       *               because of a type mismatch.
       */
      @SafeVarargs
      public static <T> T[] combine(final @NonNull T first, final @Nullable  T... rest) {
          final int restLength = _NullSafe.size(rest);
          final T[] all = _Casts.uncheckedCast(Array.newInstance(first.getClass(), restLength+1));
          all[0] = first;
          if(restLength>0) {
              System.arraycopy(rest, 0, all, 1, restLength);
          }
          return all;
      }
  
      /**
       * Returns a new array containing all components {first, *rest}
       * @param type (non-null) explicit array element type
       * @param first (non-null)
       * @param rest (nullable)
       * @return (non-null)
       */
      @SafeVarargs
      public static <T, X extends T, Y extends T> T[] combineWithExplicitType(final @NonNull Class<T> type, final @NonNull X first, final @Nullable  Y... rest) {
          final int restLength = _NullSafe.size(rest);
          final T[] all = _Casts.uncheckedCast(Array.newInstance(type, restLength+1));
          all[0] = first;
          if(restLength>0) {
              System.arraycopy(rest, 0, all, 1, restLength);
          }
          return all;
      }
  
      /**
       * Returns a new array containing all components {*first, *rest}
       * @param first (nullable)
       * @param rest (nullable)
       * @return (non-null)
       */
      @SafeVarargs
      public static <T> T[] combine(final T[] first, final T... rest) {
          final int firstLength = _NullSafe.size(first);
          final int restLength = _NullSafe.size(rest);
          if(firstLength + restLength == 0) {
              return _Casts.uncheckedCast(_Constants.emptyObjects);
          }
          final Class<?> componentType = firstLength>0 ? first[0].getClass() : rest[0].getClass();
          final T[] all = _Casts.uncheckedCast(Array.newInstance(componentType, firstLength + restLength));
          System.arraycopy(first, 0, all, 0, firstLength);
          System.arraycopy(rest, 0, all, firstLength, restLength);
          return all;
      }
  
      // -- CONSTRUCTION
  
      /**
       * Copies a collection's elements into an array.
       *
       * @param collection - the collection to convert
       * @param componentType - type of the elements
       * @return a newly-allocated array into which all the elements of the iterable
       *     have been copied (non-null)
       */
      public static <T> T[] toArray(
              final @Nullable Collection<? extends T> collection,
              final @NonNull  Class<T> componentType) {
          return _NullSafe.stream(collection)
                  .collect(toArray(componentType, collection!=null ? collection.size() : 0));
      }
  
      /**
       * Copies an iterable's elements into an array.
       *
       * @param iterable - the iterable to copy
       * @param componentType - type of the elements
       * @return a newly-allocated array into which all the elements of the iterable
       *     have been copied (non-null)
       */
      public static <T> T[] toArray(
              final @Nullable Iterable<? extends T> iterable,
              final @NonNull  Class<T> componentType) {
  // unnecessary optimization
  //        if(iterable!=null && (iterable instanceof Collection)) {
  //            return toArray((Collection<? extends T>) iterable, componentType);
  //        }
          return _NullSafe.stream(iterable)
                  .collect(toArray(componentType));
      }
  
      // -- MODIFICATION
  
      /**
       * Returns a new array of size {@code array.length - 1} with the element at {@code array[index]} removed.
       *
       * @param <T>
       * @param array
       * @param index
       */
      public static <T> T[] removeByIndex(final T[] array, final int index) {
          if(array==null || array.length<1) {
              throw new IllegalArgumentException("Array must be of lenght 1 or larger.");
          }
          if(index<0 || index>=array.length) {
              var msg = String.format("Array index %d is out of bounds [0, %d]", index, array.length-1);
              throw new IllegalArgumentException(msg);
          }
          final T[] result = Arrays.copyOf(array, array.length - 1);
          // copy the elements from index + 1 till end
          // from original array to the new array
          var remaining = result.length - index;
          System.arraycopy(array, index+1, result, index, remaining);
          return result;
      }
  
      /**
       * Returns {@code null} if given {@code array} is {@code null} or of length zero,
       * returns given {@code array} otherwise.
       *
       * @param <T>
       * @param array
       * @return null for empty arrays
       */
      public static @Nullable <T> T[] emptyToNull(final @Nullable T[] array) {
          if(array!=null && array.length==0) {
              return null;
          }
          return array;
      }
  
      /**
       * Returns a sub-array of given array. The
       * sub-array begins at the specified {@code beginIndex} and
       * extends to the element at index {@code endIndex - 1}.
       * Thus the length of the sub-array is {@code endIndex-beginIndex}.
       *
       * @param      array
       * @param      beginIndex   the beginning index, inclusive.
       * @param      endIndex     the ending index, exclusive.
       * @return     the specified sub-array, which always is a copy
       * @exception  IndexOutOfBoundsException  if the
       *             {@code beginIndex} is negative, or
       *             {@code endIndex} is larger than the length of
       *             {@code array} object, or
       *             {@code beginIndex} is larger than
       *             {@code endIndex}.
       */
      public static <T> T[] subArray(final @NonNull T[] array, final int beginIndex, final int endIndex) {
          if (beginIndex < 0) {
              throw new ArrayIndexOutOfBoundsException(beginIndex);
          }
          if (endIndex > array.length) {
              throw new ArrayIndexOutOfBoundsException(endIndex);
          }
          final int subLen = endIndex - beginIndex;
          if (subLen < 0) {
              throw new ArrayIndexOutOfBoundsException(subLen);
          }
          return Arrays.copyOfRange(array, beginIndex, endIndex);
      }
  
      // -- COMPONENT TYPE INFERENCE
  
      /**
       * Returns the inferred element type of the specified array type
       * @param arrayType - type of the array for which to infer the element type
       * @return optionally the inferred type, based on whether inference is possible
       */
      public static Optional<Class<?>> inferComponentType(
              final @Nullable Class<?> arrayType) {
          if(!isArrayType(arrayType)) {
              return Optional.empty();
          }
          return Optional.ofNullable(arrayType.getComponentType());
      }
  
      // -- ACCESSOR
  
      /**
       * Optionally returns an array element by index, based on whether the index is valid.
       * @param <T>
       * @param array
       * @param index
       */
      public static <T> Optional<T> get(final @Nullable T[] array, final int index) {
          var size = _NullSafe.size(array);
          if(size==0) {
              return Optional.empty();
          }
          var minIndex = 0;
          var maxIndex = size - 1;
          if(index < minIndex ||  index > maxIndex) {
              return Optional.empty();
          }
          return Optional.ofNullable(array[index]);
      }
  
      // -- TRANSFORMATION
  
      /**
       * Transforms given {@code array} into a new array of {@code resultElementType} and same size,
       * applying the {@code mapper} function
       * to each element of {@code array}.
       * Returns {@code null} if {@code array} is {@code null};
       * @param <T>
       * @param <R>
       * @param array
       * @param resultElementType
       * @param mapper
       * @return nullable
       */
      @Nullable
      public static <T, R> R[] map(
              final @Nullable T[] array,
              final @NonNull Class<R> resultElementType,
              final @NonNull Function<T, R> mapper) {
  
          if (array == null) {
              return null;
          }
          var mappedArray = _Casts.<R[]>uncheckedCast(
                  Array.newInstance(resultElementType, array.length));
          int i = 0;
          for (var element : array) {
              mappedArray[i++] = mapper.apply(element);
          }
          return mappedArray;
      }
  
      /**
       * Transforms given {@code array} into a new object array of same size,
       * applying the {@code mapper} function
       * to each element of {@code array}.
       * Returns {@code null} if {@code array} is {@code null};
       * @param <T>
       * @param array
       * @param mapper
       * @return nullable
       */
      @Nullable
      public static <T> Object[] map(
              final @Nullable T[] array,
              final @NonNull Function<T, ?> mapper) {
  
          if (array == null) {
              return null;
          }
          var mappedArray = new Object[array.length];
          int i = 0;
          for (var element : array) {
              mappedArray[i++] = mapper.apply(element);
          }
          return mappedArray;
      }
  
      /**
       * Transforms given {@code collection} into an array of {@code resultElementType} and same size,
       * applying the {@code mapper} function
       * to each element of {@code collection}.
       * Returns {@code null} if {@code collection} is {@code null};
       * @param <T>
       * @param <R>
       * @param collection
       * @param resultElementType
       * @param mapper
       * @return nullable
       */
      @Nullable
      public static <T, R> R[] mapCollection(
              final @Nullable Collection<T> collection,
              final @NonNull Class<R> resultElementType,
              final @NonNull Function<T, R> mapper) {
  
          if (collection == null) {
              return null;
          }
          var mappedArray = _Casts.<R[]>uncheckedCast(
                  Array.newInstance(resultElementType, collection.size()));
          int i = 0;
          for (var element : collection) {
              mappedArray[i++] = mapper.apply(element);
          }
          return mappedArray;
      }
  
      /**
       * Transforms given {@code collection} into an object array of same size,
       * applying the {@code mapper} function
       * to each element of {@code collection}.
       * Returns {@code null} if {@code collection} is {@code null};
       * @param <T>
       * @param collection
       * @param mapper
       * @return nullable
       */
      @Nullable
      public static <T> Object[] mapCollection(
              final @Nullable Collection<T> collection,
              final @NonNull Function<T, ?> mapper) {
  
          if (collection == null) {
              return null;
          }
          var mappedArray = new Object[collection.size()];
          int i = 0;
          for (var element : collection) {
              mappedArray[i++] = mapper.apply(element);
          }
          return mappedArray;
      }
  
      // --
  
  }
  