/*
 * Java Genetic Algorithm Library (jenetics-8.0.0).
 * Copyright (c) 2007-2024 Franz Wilhelmstötter
 *
 * Licensed 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.
 *
 * Author:
 *    Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
 */
package io.jenetics.ext.internal.util;

import static java.lang.Math.max;
import static java.lang.String.format;
import static java.lang.System.arraycopy;
import static java.util.Arrays.copyOf;
import static java.util.Objects.requireNonNull;

import java.util.Arrays;
import java.util.function.IntConsumer;
import java.util.stream.IntStream;

/**
 * Resizable-int array implementation
 *
 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
 * @version 4.3
 * @since 4.1
 */
public final class IntList {

        private static final int MAX_SIZE = Integer.MAX_VALUE - 8;
        private static final int DEFAULT_CAPACITY = 10;
        private static final int[] EMPTY_ARRAY = {};
        private static final int[] DEFAULT_EMPTY_ARRAY = {};

        private int[] _data;
        private int _size;

        /**
         * Constructs an empty list with the specified initial capacity.
         *
         * @param  capacity  the initial capacity of the list
         * @throws IllegalArgumentException if the specified initial capacity
         *         is negative
         */
        public IntList(final int capacity) {
                if (capacity > 0) {
                        _data = new int[capacity];
                } else if (capacity == 0) {
                        _data = EMPTY_ARRAY;
                } else {
                        throw new IllegalArgumentException("Illegal Capacity: "+ capacity);
                }
        }

        /**
         * Constructs an empty list with an initial capacity of ten.
         */
        public IntList() {
                _data = DEFAULT_EMPTY_ARRAY;
        }

        /**
         * Returns the element at the specified position in this list.
         *
         * @param  index index of the element to return
         * @return the element at the specified position in this list
         * @throws IndexOutOfBoundsException if the index is out of range
         *         {@code (index < 0 || index > size())}
         */
        public int get(final int index) {
                rangeCheck(index);

                return _data[index];
        }

        /**
         * Performs the given action for each element of the list.
         *
         * @param action the action to be performed for each element
         * @throws NullPointerException if the specified action is {@code null}
         */
        public void forEach(final IntConsumer action) {
                requireNonNull(action);

                final int size = _size;
                for (int i = 0; i < size; ++i) {
                        action.accept(_data[i]);
                }
        }

        /**
         * Returns a sequential {@link IntStream} with the specified list as its
         * source.
         *
         * @return a sequential {@link IntStream}
         */
        public IntStream stream() {
                return Arrays.stream(_data, 0, _size);
        }

        /**
         * Appends the specified element to the end of this list.
         *
         * @param element element to be appended to this list
         */
        public void add(final int element) {
                ensureSize(_size + 1);
                _data[_size++] = element;
        }

        /**
         * Inserts the specified element at the specified position in this list.
         * Shifts the element currently at that position (if any) and any subsequent
         * elements to the right (adds one to their indices).
         *
         * @param index index at which the specified element is to be inserted
         * @param element element to be inserted
         * @throws IndexOutOfBoundsException if the index is out of range
         *         {@code (index < 0 || index > size())}
         */
        public void add(final int index, final int element) {
                addRangeCheck(index);

                ensureSize(_size + 1);
                arraycopy(
                        _data, index,
                        _data, index + 1,
                        _size - index
                );
                _data[index] = element;
                _size++;
        }

        /**
         * Appends all of the elements in the specified array to the end of this
         * list.
         *
         * @param elements array containing elements to be added to this list
         * @return {@code true} if this list changed as a result of the call
         * @throws NullPointerException if the specified array is null
         */
        public boolean addAll(final int[] elements) {
                final int count = elements.length;
                ensureSize(_size + count);
                arraycopy(elements, 0, _data, _size, count);
                _size += count;

                return count != 0;
        }

        /**
         * Inserts all the elements in the specified array into this list, starting
         * at the specified position.
         *
         * @param index index at which to insert the first element from the
         *              specified collection
         * @param elements collection containing elements to be added to this list
         * @return {@code true} if this list changed as a result of the call
         * @throws IndexOutOfBoundsException if the index is out of range
         *         {@code (index < 0 || index > size())}
         * @throws NullPointerException if the specified array is null
         */
        public boolean addAll(final int index, final int[] elements) {
                addRangeCheck(index);

                final int count = elements.length;
                ensureSize(_size + count);

                final int moved = _size - index;
                if (moved > 0) {
                        arraycopy(_data, index, _data, index + count, moved);
                }

                arraycopy(elements, 0, _data, index, count);
                _size += count;
                return count != 0;
        }

        /**
         * Removes all of the elements from this list. The list will be empty after
         * this call returns.
         */
        public void clear() {
                _size = 0;
        }

        /**
         * Trims the capacity of this {@code ArrayList} instance to be the list's
         * current size.  An application can use this operation to minimize the
         * storage of an {@code ArrayList} instance.
         */
        public void trimToSize() {
                if (_size < _data.length) {
                        _data = _size == 0
                                ? EMPTY_ARRAY
                                : copyOf(_data, _size);
                }
        }

        /**
         * Returns the number of elements in this list.
         *
         * @return the number of elements in this list
         */
        public int size() {
                return _size;
        }

        /**
         * Return {@code true} if the list is empty.
         *
         * @return {@code true} if the list is empty, {@code false} otherwise
         */
        public boolean isEmpty() {
                return _size == 0;
        }

        /**
         * Return the current elements as an int array.
         *
         * @return the current elements as an int array
         */
        public int[] toArray() {
                return copyOf(_data, _size);
        }

        private void ensureSize(int size) {
                ensureExplicitSize(capacity(_data, size));
        }

        private void ensureExplicitSize(int size) {
                if (size - _data.length > 0) {
                        grow(size);
                }
        }

        private void rangeCheck(final int index) {
                if (index >= _size)
                        throw new IndexOutOfBoundsException(format(
                                "Index: %d, Size: %d", index, _size
                        ));
        }

        private void addRangeCheck(int index) {
                if (index > _size || index < 0)
                        throw new IndexOutOfBoundsException(format(
                                "Index: %d, Size: %d", index, _size
                        ));
        }

        private static int capacity(final int[] data, final int capacity) {
                if (data == DEFAULT_EMPTY_ARRAY) {
                        return max(DEFAULT_CAPACITY, capacity);
                }
                return capacity;
        }

        private void grow(final int size) {
                final int oldSize = _data.length;

                int newSize = oldSize + (oldSize >> 1);
                if (newSize - size < 0) {
                        newSize = size;
                }
                if (newSize - MAX_SIZE > 0) {
                        newSize = hugeCapacity(size);
                }

                _data = copyOf(_data, newSize);
        }

        private static int hugeCapacity(final int minCapacity) {
                if (minCapacity < 0) {
                        throw new OutOfMemoryError();
                }

                return minCapacity > MAX_SIZE
                        ? Integer.MAX_VALUE
                        : MAX_SIZE;
        }

}