using J2N.Collections;
using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Text;

namespace Lucene.Net.Support
{
    /*
     * 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.
     */

    internal static class Arrays
    {
        /// <summary>
        /// Compares the entire members of one array whith the other one.
        /// </summary>
        /// <param name="a">The array to be compared.</param>
        /// <param name="b">The array to be compared with.</param>
        /// <returns>Returns true if the two specified arrays of Objects are equal
        /// to one another. The two arrays are considered equal if both arrays
        /// contain the same number of elements, and all corresponding pairs of
        /// elements in the two arrays are equal. Two objects e1 and e2 are
        /// considered equal if (e1==null ? e2==null : e1.Equals(e2)). In other
        /// words, the two arrays are equal if they contain the same elements in
        /// the same order. Also, two array references are considered equal if
        /// both are null.
        /// <para/>
        /// Note that if the type of <typeparam name="T"/> is a <see cref="IDictionary{TKey, TValue}"/>,
        /// <see cref="IList{T}"/>, or <see cref="ISet{T}"/>, its values and any nested collection values
        /// will be compared for equality as well.
        /// </returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static bool Equals<T>(T[] a, T[] b)
        {
            return ArrayEqualityComparer<T>.OneDimensional.Equals(a, b);
        }

        /// <summary>
        /// Returns a hash code based on the contents of the given array. For any two
        /// <typeparamref name="T"/> arrays <c>a</c> and <c>b</c>, if
        /// <c>Arrays.Equals(b)</c> returns <c>true</c>, it means
        /// that the return value of <c>Arrays.GetHashCode(a)</c> equals <c>Arrays.GetHashCode(b)</c>.
        /// </summary>
        /// <typeparam name="T">The array element type.</typeparam>
        /// <param name="array">The array whose hash code to compute.</param>
        /// <returns>The hash code for <paramref name="array"/>.</returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static int GetHashCode<T>(T[] array)
        {
            return ArrayEqualityComparer<T>.OneDimensional.GetHashCode(array);
        }

        /// <summary>
        /// Assigns the specified value to each element of the specified array.
        /// </summary>
        /// <typeparam name="T">the type of the array</typeparam>
        /// <param name="a">the array to be filled</param>
        /// <param name="val">the value to be stored in all elements of the array</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void Fill<T>(T[] a, T val)
        {
            for (int i = 0; i < a.Length; i++)
            {
                a[i] = val;
            }
        }

        /// <summary>
        /// Assigns the specified long value to each element of the specified
        /// range of the specified array of longs.  The range to be filled
        /// extends from index <paramref name="fromIndex"/>, inclusive, to index
        /// <paramref name="toIndex"/>, exclusive.  (If <c>fromIndex==toIndex</c>, the
        /// range to be filled is empty.)
        /// </summary>
        /// <typeparam name="T">the type of the array</typeparam>
        /// <param name="a">the array to be filled</param>
        /// <param name="fromIndex">
        /// the index of the first element (inclusive) to be
        /// filled with the specified value
        /// </param>
        /// <param name="toIndex">
        /// the index of the last element (exclusive) to be
        /// filled with the specified value
        /// </param>
        /// <param name="val">the value to be stored in all elements of the array</param>
        /// <exception cref="ArgumentException">if <c>fromIndex &gt; toIndex</c></exception>
        /// <exception cref="ArgumentOutOfRangeException">if <c>fromIndex &lt; 0</c> or <c>toIndex &gt; a.Length</c></exception>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void Fill<T>(T[] a, int fromIndex, int toIndex, T val)
        {
            //Java Arrays.fill exception logic
            if (fromIndex > toIndex)
                throw new ArgumentException("fromIndex(" + fromIndex + ") > toIndex(" + toIndex + ")");
            if (fromIndex < 0)
                throw new ArgumentOutOfRangeException(nameof(fromIndex));
            if (toIndex > a.Length)
                throw new ArgumentOutOfRangeException(nameof(toIndex));

            for (int i = fromIndex; i < toIndex; i++)
            {
                a[i] = val;
            }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static T[] CopyOf<T>(T[] original, int newLength)
        {
            T[] newArray = new T[newLength];

            for (int i = 0; i < Math.Min(original.Length, newLength); i++)
            {
                newArray[i] = original[i];
            }

            return newArray;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static T[] CopyOfRange<T>(T[] original, int startIndexInc, int endIndexExc)
        {
            int newLength = endIndexExc - startIndexInc;
            T[] newArray = new T[newLength];

            for (int i = startIndexInc, j = 0; i < endIndexExc; i++, j++)
            {
                newArray[j] = original[i];
            }

            return newArray;
        }

        /// <summary>
        /// Creates a <see cref="string"/> representation of the array passed.
        /// The result is surrounded by brackets <c>"[]"</c>, each
        /// element is converted to a <see cref="string"/> via the
        /// <see cref="J2N.Text.StringFormatter.InvariantCulture"/> and separated by <c>", "</c>. If
        /// the array is <c>null</c>, then <c>"null"</c> is returned.
        /// </summary>
        /// <typeparam name="T">The type of array element.</typeparam>
        /// <param name="array"></param>
        public static string ToString<T>(T[] array)
        {
            if (array == null)
                return "null"; //$NON-NLS-1$
            if (array.Length == 0)
                return "[]"; //$NON-NLS-1$
            StringBuilder sb = new StringBuilder(2 + array.Length * 4);
            sb.Append('[');
            sb.AppendFormat(J2N.Text.StringFormatter.InvariantCulture, "{0}", array[0]);
            for (int i = 1; i < array.Length; i++)
            {
                sb.Append(", "); //$NON-NLS-1$
                sb.AppendFormat(J2N.Text.StringFormatter.InvariantCulture, "{0}", array[i]);
            }
            sb.Append(']');
            return sb.ToString();
        }

        /// <summary>
        /// Returns an empty array.
        /// </summary>
        /// <typeparam name="T">The type of the elements of the array.</typeparam>
        /// <returns>An empty array.</returns>
        // LUCENENET: Since Array.Empty<T>() doesn't exist in all supported platforms, we
        // have this wrapper method to add support.
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static T[] Empty<T>()
        {
#if FEATURE_ARRAYEMPTY
            return Array.Empty<T>();
#else
            return EmptyArrayHolder<T>.EMPTY;
#endif
        }

        private static class EmptyArrayHolder<T>
        {
#pragma warning disable CA1825 // Avoid zero-length array allocations.
            public static readonly T[] EMPTY = new T[0];
#pragma warning restore CA1825 // Avoid zero-length array allocations.
        }
    }
}
