using System;
using System.Diagnostics;
using Unity.Jobs;
using Unity.Mathematics;

namespace Unity.Collections.LowLevel.Unsafe
{
    /// <summary>
    /// An arbitrarily-sized array of bits.
    /// </summary>
    /// <remarks>
    /// The number of allocated bytes is always a multiple of 8. For example, a 65-bit array could fit in 9 bytes, but its allocation is actually 16 bytes.
    /// </remarks>
    [DebuggerDisplay("Length = {Length}, IsCreated = {IsCreated}")]
    [DebuggerTypeProxy(typeof(UnsafeBitArrayDebugView))]
    [BurstCompatible]
    public unsafe struct UnsafeBitArray
        : INativeDisposable
    {
        /// <summary>
        /// Pointer to the data.
        /// </summary>
        /// <value>Pointer to the data.</value>
        [NativeDisableUnsafePtrRestriction]
        public ulong* Ptr;

        /// <summary>
        /// The number of bits.
        /// </summary>
        /// <value>The number of bits.</value>
        public int Length;

        /// <summary>
        /// The allocator to use.
        /// </summary>
        /// <value>The allocator to use.</value>
        public AllocatorManager.AllocatorHandle Allocator;

        /// <summary>
        /// Initializes and returns an instance of UnsafeBitArray which aliases an existing buffer.
        /// </summary>
        /// <param name="ptr">An existing buffer.</param>
        /// <param name="allocator">The allocator that was used to allocate the bytes. Needed to dispose this array.</param>
        /// <param name="sizeInBytes">The number of bytes. The length will be `sizeInBytes * 8`.</param>
        public unsafe UnsafeBitArray(void* ptr, int sizeInBytes, AllocatorManager.AllocatorHandle allocator = new AllocatorManager.AllocatorHandle())
        {
            CheckSizeMultipleOf8(sizeInBytes);
            Ptr = (ulong*)ptr;
            Length = sizeInBytes * 8;
            Allocator = allocator;
        }

        /// <summary>
        /// Initializes and returns an instance of UnsafeBitArray.
        /// </summary>
        /// <param name="numBits">Number of bits.</param>
        /// <param name="allocator">The allocator to use.</param>
        /// <param name="options">Whether newly allocated bytes should be zeroed out.</param>
        public UnsafeBitArray(int numBits, AllocatorManager.AllocatorHandle allocator, NativeArrayOptions options = NativeArrayOptions.ClearMemory)
        {
            CollectionHelper.CheckAllocator(allocator);
            Allocator = allocator;
            var sizeInBytes = Bitwise.AlignUp(numBits, 64) / 8;
            Ptr = (ulong*)Memory.Unmanaged.Allocate(sizeInBytes, 16, allocator);
            Length = numBits;

            if (options == NativeArrayOptions.ClearMemory)
            {
                UnsafeUtility.MemClear(Ptr, sizeInBytes);
            }
        }

        /// <summary>
        /// Whether this array has been allocated (and not yet deallocated).
        /// </summary>
        /// <value>True if this array has been allocated (and not yet deallocated).</value>
        public bool IsCreated => Ptr != null;

        /// <summary>
        /// Releases all resources (memory and safety handles).
        /// </summary>
        public void Dispose()
        {
            if (CollectionHelper.ShouldDeallocate(Allocator))
            {
                Memory.Unmanaged.Free(Ptr, Allocator);
                Allocator = AllocatorManager.Invalid;
            }

            Ptr = null;
            Length = 0;
        }

        /// <summary>
        /// Creates and schedules a job that will dispose this array.
        /// </summary>
        /// <param name="inputDeps">The handle of a job which the new job will depend upon.</param>
        /// <returns>The handle of a new job that will dispose this array. The new job depends upon inputDeps.</returns>
        [NotBurstCompatible /* This is not burst compatible because of IJob's use of a static IntPtr. Should switch to IJobBurstSchedulable in the future */]
        public JobHandle Dispose(JobHandle inputDeps)
        {
            if (CollectionHelper.ShouldDeallocate(Allocator))
            {
                var jobHandle = new UnsafeDisposeJob { Ptr = Ptr, Allocator = Allocator }.Schedule(inputDeps);

                Ptr = null;
                Allocator = AllocatorManager.Invalid;

                return jobHandle;
            }

            Ptr = null;

            return inputDeps;
        }

        /// <summary>
        /// Sets all the bits to 0.
        /// </summary>
        public void Clear()
        {
            var sizeInBytes = Bitwise.AlignUp(Length, 64) / 8;
            UnsafeUtility.MemClear(Ptr, sizeInBytes);
        }

        /// <summary>
        /// Sets the bit at an index to 0 or 1.
        /// </summary>
        /// <param name="pos">Index of the bit to set.</param>
        /// <param name="value">True for 1, false for 0.</param>
        public void Set(int pos, bool value)
        {
            CheckArgs(pos, 1);

            var idx = pos >> 6;
            var shift = pos & 0x3f;
            var mask = 1ul << shift;
            var bits = (Ptr[idx] & ~mask) | ((ulong)-Bitwise.FromBool(value) & mask);
            Ptr[idx] = bits;
        }

        /// <summary>
        /// Sets a range of bits to 0 or 1.
        /// </summary>
        /// <remarks>
        /// The range runs from index `pos` up to (but not including) `pos + numBits`.
        /// No exception is thrown if `pos + numBits` exceeds the length.
        /// </remarks>
        /// <param name="pos">Index of the first bit to set.</param>
        /// <param name="value">True for 1, false for 0.</param>
        /// <param name="numBits">Number of bits to set.</param>
        /// <exception cref="ArgumentException">Thrown if pos is out of bounds or if numBits is less than 1.</exception>
        public void SetBits(int pos, bool value, int numBits)
        {
            CheckArgs(pos, numBits);

            var end = math.min(pos + numBits, Length);
            var idxB = pos >> 6;
            var shiftB = pos & 0x3f;
            var idxE = (end - 1) >> 6;
            var shiftE = end & 0x3f;
            var maskB = 0xfffffffffffffffful << shiftB;
            var maskE = 0xfffffffffffffffful >> (64 - shiftE);
            var orBits = (ulong)-Bitwise.FromBool(value);
            var orBitsB = maskB & orBits;
            var orBitsE = maskE & orBits;
            var cmaskB = ~maskB;
            var cmaskE = ~maskE;

            if (idxB == idxE)
            {
                var maskBE = maskB & maskE;
                var cmaskBE = ~maskBE;
                var orBitsBE = orBitsB & orBitsE;
                Ptr[idxB] = (Ptr[idxB] & cmaskBE) | orBitsBE;
                return;
            }

            Ptr[idxB] = (Ptr[idxB] & cmaskB) | orBitsB;

            for (var idx = idxB + 1; idx < idxE; ++idx)
            {
                Ptr[idx] = orBits;
            }

            Ptr[idxE] = (Ptr[idxE] & cmaskE) | orBitsE;
        }

        /// <summary>
        /// Copies bits of a ulong to bits in this array.
        /// </summary>
        /// <remarks>
        /// The destination bits in this array run from index `pos` up to (but not including) `pos + numBits`.
        /// No exception is thrown if `pos + numBits` exceeds the length.
        ///
        /// The lowest bit of the ulong is copied to the first destination bit; the second-lowest bit of the ulong is
        /// copied to the second destination bit; and so forth.
        /// </remarks>
        /// <param name="pos">Index of the first bit to set.</param>
        /// <param name="value">Unsigned long from which to copy bits.</param>
        /// <param name="numBits">Number of bits to set (must be between 1 and 64).</param>
        /// <exception cref="ArgumentException">Thrown if pos is out of bounds or if numBits is not between 1 and 64.</exception>
        public void SetBits(int pos, ulong value, int numBits = 1)
        {
            CheckArgsUlong(pos, numBits);

            var idxB = pos >> 6;
            var shiftB = pos & 0x3f;

            if (shiftB + numBits <= 64)
            {
                var mask = 0xfffffffffffffffful >> (64 - numBits);
                Ptr[idxB] = Bitwise.ReplaceBits(Ptr[idxB], shiftB, mask, value);

                return;
            }

            var end = math.min(pos + numBits, Length);
            var idxE = (end - 1) >> 6;
            var shiftE = end & 0x3f;

            var maskB = 0xfffffffffffffffful >> shiftB;
            Ptr[idxB] = Bitwise.ReplaceBits(Ptr[idxB], shiftB, maskB, value);

            var valueE = value >> (64 - shiftB);
            var maskE = 0xfffffffffffffffful >> (64 - shiftE);
            Ptr[idxE] = Bitwise.ReplaceBits(Ptr[idxE], 0, maskE, valueE);
        }

        /// <summary>
        /// Returns a ulong which has bits copied from this array.
        /// </summary>
        /// <remarks>
        /// The source bits in this array run from index `pos` up to (but not including) `pos + numBits`.
        /// No exception is thrown if `pos + numBits` exceeds the length.
        ///
        /// The first source bit is copied to the lowest bit of the ulong; the second source bit is copied to the second-lowest bit of the ulong; and so forth. Any remaining bits in the ulong will be 0.
        /// </remarks>
        /// <param name="pos">Index of the first bit to get.</param>
        /// <param name="numBits">Number of bits to get (must be between 1 and 64).</param>
        /// <exception cref="ArgumentException">Thrown if pos is out of bounds or if numBits is not between 1 and 64.</exception>
        /// <returns>A ulong which has bits copied from this array.</returns>
        public ulong GetBits(int pos, int numBits = 1)
        {
            CheckArgsUlong(pos, numBits);

            var idxB = pos >> 6;
            var shiftB = pos & 0x3f;

            if (shiftB + numBits <= 64)
            {
                var mask = 0xfffffffffffffffful >> (64 - numBits);
                return Bitwise.ExtractBits(Ptr[idxB], shiftB, mask);
            }

            var end = math.min(pos + numBits, Length);
            var idxE = (end - 1) >> 6;
            var shiftE = end & 0x3f;

            var maskB = 0xfffffffffffffffful >> shiftB;
            ulong valueB = Bitwise.ExtractBits(Ptr[idxB], shiftB, maskB);

            var maskE = 0xfffffffffffffffful >> (64 - shiftE);
            ulong valueE = Bitwise.ExtractBits(Ptr[idxE], 0, maskE);

            return (valueE << (64 - shiftB)) | valueB;
        }

        /// <summary>
        /// Returns true if the bit at an index is 1.
        /// </summary>
        /// <param name="pos">Index of the bit to test.</param>
        /// <returns>True if the bit at the index is 1.</returns>
        /// <exception cref="ArgumentException">Thrown if `pos` is out of bounds.</exception>
        public bool IsSet(int pos)
        {
            CheckArgs(pos, 1);

            var idx = pos >> 6;
            var shift = pos & 0x3f;
            var mask = 1ul << shift;
            return 0ul != (Ptr[idx] & mask);
        }

        internal void CopyUlong(int dstPos, ref UnsafeBitArray srcBitArray, int srcPos, int numBits) => SetBits(dstPos, srcBitArray.GetBits(srcPos, numBits), numBits);

        /// <summary>
        /// Copies a range of bits from this array to another range in this array.
        /// </summary>
        /// <remarks>
        /// The bits to copy run from index `srcPos` up to (but not including) `srcPos + numBits`.
        /// The bits to set run from index `dstPos` up to (but not including) `dstPos + numBits`.
        ///
        /// The ranges may overlap, but the result in the overlapping region is undefined.
        /// </remarks>
        /// <param name="dstPos">Index of the first bit to set.</param>
        /// <param name="srcPos">Index of the first bit to copy.</param>
        /// <param name="numBits">Number of bits to copy.</param>
        /// <exception cref="ArgumentException">Thrown if either `dstPos + numBits` or `srcPos + numBits` exceed the length of this array.</exception>
        public void Copy(int dstPos, int srcPos, int numBits)
        {
            if (dstPos == srcPos)
            {
                return;
            }

            Copy(dstPos, ref this, srcPos, numBits);
        }

        /// <summary>
        /// Copies a range of bits from an array to a range of bits in this array.
        /// </summary>
        /// <remarks>
        /// The bits to copy in the source array run from index srcPos up to (but not including) `srcPos + numBits`.
        /// The bits to set in the destination array run from index dstPos up to (but not including) `dstPos + numBits`.
        ///
        /// It's fine if source and destination array are one and the same, even if the ranges overlap, but the result in the overlapping region is undefined.
        /// </remarks>
        /// <param name="dstPos">Index of the first bit to set.</param>
        /// <param name="srcBitArray">The source array.</param>
        /// <param name="srcPos">Index of the first bit to copy.</param>
        /// <param name="numBits">The number of bits to copy.</param>
        /// <exception cref="ArgumentException">Thrown if either `dstPos + numBits` or `srcBitArray + numBits` exceed the length of this array.</exception>
        public void Copy(int dstPos, ref UnsafeBitArray srcBitArray, int srcPos, int numBits)
        {
            if (numBits == 0)
            {
                return;
            }

            CheckArgsCopy(ref this, dstPos, ref srcBitArray, srcPos, numBits);

            if (numBits <= 64) // 1x CopyUlong
            {
                CopyUlong(dstPos, ref srcBitArray, srcPos, numBits);
            }
            else if (numBits <= 128) // 2x CopyUlong
            {
                CopyUlong(dstPos, ref srcBitArray, srcPos, 64);
                numBits -= 64;

                if (numBits > 0)
                {
                    CopyUlong(dstPos + 64, ref srcBitArray, srcPos + 64, numBits);
                }
            }
            else if ((dstPos & 7) == (srcPos & 7)) // aligned copy
            {
                var dstPosInBytes = CollectionHelper.Align(dstPos, 8) >> 3;
                var srcPosInBytes = CollectionHelper.Align(srcPos, 8) >> 3;
                var numPreBits = dstPosInBytes * 8 - dstPos;

                if (numPreBits > 0)
                {
                    CopyUlong(dstPos, ref srcBitArray, srcPos, numPreBits);
                }

                var numBitsLeft = numBits - numPreBits;
                var numBytes = numBitsLeft / 8;

                if (numBytes > 0)
                {
                    unsafe
                    {
                        UnsafeUtility.MemMove((byte*)Ptr + dstPosInBytes, (byte*)srcBitArray.Ptr + srcPosInBytes, numBytes);
                    }
                }

                var numPostBits = numBitsLeft & 7;

                if (numPostBits > 0)
                {
                    CopyUlong((dstPosInBytes + numBytes) * 8, ref srcBitArray, (srcPosInBytes + numBytes) * 8, numPostBits);
                }
            }
            else // unaligned copy
            {
                var dstPosAligned = CollectionHelper.Align(dstPos, 64);
                var numPreBits = dstPosAligned - dstPos;

                if (numPreBits > 0)
                {
                    CopyUlong(dstPos, ref srcBitArray, srcPos, numPreBits);
                    numBits -= numPreBits;
                    dstPos += numPreBits;
                    srcPos += numPreBits;
                }

                for (; numBits >= 64; numBits -= 64, dstPos += 64, srcPos += 64)
                {
                    Ptr[dstPos >> 6] = srcBitArray.GetBits(srcPos, 64);
                }

                if (numBits > 0)
                {
                    CopyUlong(dstPos, ref srcBitArray, srcPos, numBits);
                }
            }
        }

        /// <summary>
        /// Returns the index of the first occurrence in this array of *N* contiguous 0 bits.
        /// </summary>
        /// <remarks>The search is linear.</remarks>
        /// <param name="pos">Index of the bit at which to start searching.</param>
        /// <param name="numBits">Number of contiguous 0 bits to look for.</param>
        /// <returns>The index of the first occurrence in this array of `numBits` contiguous 0 bits. Range is pos up to (but not including) the length of this array. Returns -1 if no occurrence is found.</returns>
        public int Find(int pos, int numBits)
        {
            var count = Length - pos;
            CheckArgsPosCount(pos, count, numBits);
            return Bitwise.Find(Ptr, pos, count, numBits);
        }

        /// <summary>
        /// Returns the index of the first occurrence in this array of a given number of contiguous 0 bits.
        /// </summary>
        /// <remarks>The search is linear.</remarks>
        /// <param name="pos">Index of the bit at which to start searching.</param>
        /// <param name="numBits">Number of contiguous 0 bits to look for.</param>
        /// <param name="count">Number of indexes to consider as the return value.</param>
        /// <returns>The index of the first occurrence in this array of `numBits` contiguous 0 bits. Range is pos up to (but not including) `pos + count`. Returns -1 if no occurrence is found.</returns>
        public int Find(int pos, int count, int numBits)
        {
            CheckArgsPosCount(pos, count, numBits);
            return Bitwise.Find(Ptr, pos, count, numBits);
        }

        /// <summary>
        /// Returns true if none of the bits in a range are 1 (*i.e.* all bits in the range are 0).
        /// </summary>
        /// <param name="pos">Index of the bit at which to start searching.</param>
        /// <param name="numBits">Number of bits to test. Defaults to 1.</param>
        /// <returns>Returns true if none of the bits in range `pos` up to (but not including) `pos + numBits` are 1.</returns>
        /// <exception cref="ArgumentException">Thrown if `pos` is out of bounds or `numBits` is less than 1.</exception>
        public bool TestNone(int pos, int numBits = 1)
        {
            CheckArgs(pos, numBits);

            var end = math.min(pos + numBits, Length);
            var idxB = pos >> 6;
            var shiftB = pos & 0x3f;
            var idxE = (end - 1) >> 6;
            var shiftE = end & 0x3f;
            var maskB = 0xfffffffffffffffful << shiftB;
            var maskE = 0xfffffffffffffffful >> (64 - shiftE);

            if (idxB == idxE)
            {
                var mask = maskB & maskE;
                return 0ul == (Ptr[idxB] & mask);
            }

            if (0ul != (Ptr[idxB] & maskB))
            {
                return false;
            }

            for (var idx = idxB + 1; idx < idxE; ++idx)
            {
                if (0ul != Ptr[idx])
                {
                    return false;
                }
            }

            return 0ul == (Ptr[idxE] & maskE);
        }

        /// <summary>
        /// Returns true if at least one of the bits in a range is 1.
        /// </summary>
        /// <param name="pos">Index of the bit at which to start searching.</param>
        /// <param name="numBits">Number of bits to test. Defaults to 1.</param>
        /// <returns>True if one or more of the bits in range `pos` up to (but not including) `pos + numBits` are 1.</returns>
        /// <exception cref="ArgumentException">Thrown if `pos` is out of bounds or `numBits` is less than 1.</exception>
        public bool TestAny(int pos, int numBits = 1)
        {
            CheckArgs(pos, numBits);

            var end = math.min(pos + numBits, Length);
            var idxB = pos >> 6;
            var shiftB = pos & 0x3f;
            var idxE = (end - 1) >> 6;
            var shiftE = end & 0x3f;
            var maskB = 0xfffffffffffffffful << shiftB;
            var maskE = 0xfffffffffffffffful >> (64 - shiftE);

            if (idxB == idxE)
            {
                var mask = maskB & maskE;
                return 0ul != (Ptr[idxB] & mask);
            }

            if (0ul != (Ptr[idxB] & maskB))
            {
                return true;
            }

            for (var idx = idxB + 1; idx < idxE; ++idx)
            {
                if (0ul != Ptr[idx])
                {
                    return true;
                }
            }

            return 0ul != (Ptr[idxE] & maskE);
        }

        /// <summary>
        /// Returns true if all of the bits in a range are 1.
        /// </summary>
        /// <param name="pos">Index of the bit at which to start searching.</param>
        /// <param name="numBits">Number of bits to test. Defaults to 1.</param>
        /// <returns>True if all of the bits in range `pos` up to (but not including) `pos + numBits` are 1.</returns>
        /// <exception cref="ArgumentException">Thrown if `pos` is out of bounds or `numBits` is less than 1.</exception>
        public bool TestAll(int pos, int numBits = 1)
        {
            CheckArgs(pos, numBits);

            var end = math.min(pos + numBits, Length);
            var idxB = pos >> 6;
            var shiftB = pos & 0x3f;
            var idxE = (end - 1) >> 6;
            var shiftE = end & 0x3f;
            var maskB = 0xfffffffffffffffful << shiftB;
            var maskE = 0xfffffffffffffffful >> (64 - shiftE);

            if (idxB == idxE)
            {
                var mask = maskB & maskE;
                return mask == (Ptr[idxB] & mask);
            }

            if (maskB != (Ptr[idxB] & maskB))
            {
                return false;
            }

            for (var idx = idxB + 1; idx < idxE; ++idx)
            {
                if (0xfffffffffffffffful != Ptr[idx])
                {
                    return false;
                }
            }

            return maskE == (Ptr[idxE] & maskE);
        }

        /// <summary>
        /// Returns the number of bits in a range that are 1.
        /// </summary>
        /// <param name="pos">Index of the bit at which to start searching.</param>
        /// <param name="numBits">Number of bits to test. Defaults to 1.</param>
        /// <returns>The number of bits in a range of bits that are 1.</returns>
        /// <exception cref="ArgumentException">Thrown if `pos` is out of bounds or `numBits` is less than 1.</exception>
        public int CountBits(int pos, int numBits = 1)
        {
            CheckArgs(pos, numBits);

            var end = math.min(pos + numBits, Length);
            var idxB = pos >> 6;
            var shiftB = pos & 0x3f;
            var idxE = (end - 1) >> 6;
            var shiftE = end & 0x3f;
            var maskB = 0xfffffffffffffffful << shiftB;
            var maskE = 0xfffffffffffffffful >> (64 - shiftE);

            if (idxB == idxE)
            {
                var mask = maskB & maskE;
                return math.countbits(Ptr[idxB] & mask);
            }

            var count = math.countbits(Ptr[idxB] & maskB);

            for (var idx = idxB + 1; idx < idxE; ++idx)
            {
                count += math.countbits(Ptr[idx]);
            }

            count += math.countbits(Ptr[idxE] & maskE);

            return count;
        }

        [Conditional("ENABLE_UNITY_COLLECTIONS_CHECKS")]
        static void CheckSizeMultipleOf8(int sizeInBytes)
        {
            if ((sizeInBytes & 7) != 0)
                throw new ArgumentException($"BitArray invalid arguments: sizeInBytes {sizeInBytes} (must be multiple of 8-bytes, sizeInBytes: {sizeInBytes}).");
        }

        [Conditional("ENABLE_UNITY_COLLECTIONS_CHECKS")]
        void CheckArgs(int pos, int numBits)
        {
            if (pos < 0
                || pos >= Length
                || numBits < 1)
            {
                throw new ArgumentException($"BitArray invalid arguments: pos {pos} (must be 0-{Length - 1}), numBits {numBits} (must be greater than 0).");
            }
        }

        [Conditional("ENABLE_UNITY_COLLECTIONS_CHECKS")]
        void CheckArgsPosCount(int begin, int count, int numBits)
        {
            if (begin < 0 || begin >= Length)
            {
                throw new ArgumentException($"BitArray invalid argument: begin {begin} (must be 0-{Length - 1}).");
            }

            if (count < 0 || count > Length)
            {
                throw new ArgumentException($"BitArray invalid argument: count {count} (must be 0-{Length}).");
            }

            if (numBits < 1 || count < numBits)
            {
                throw new ArgumentException($"BitArray invalid argument: numBits {numBits} (must be greater than 0).");
            }
        }

        [Conditional("ENABLE_UNITY_COLLECTIONS_CHECKS")]
        void CheckArgsUlong(int pos, int numBits)
        {
            CheckArgs(pos, numBits);

            if (numBits < 1 || numBits > 64)
            {
                throw new ArgumentException($"BitArray invalid arguments: numBits {numBits} (must be 1-64).");
            }

            if (pos + numBits > Length)
            {
                throw new ArgumentException($"BitArray invalid arguments: Out of bounds pos {pos}, numBits {numBits}, Length {Length}.");
            }
        }

        [Conditional("ENABLE_UNITY_COLLECTIONS_CHECKS")]
        static void CheckArgsCopy(ref UnsafeBitArray dstBitArray, int dstPos, ref UnsafeBitArray srcBitArray, int srcPos, int numBits)
        {
            if (srcPos + numBits > srcBitArray.Length)
            {
                throw new ArgumentException($"BitArray invalid arguments: Out of bounds - source position {srcPos}, numBits {numBits}, source bit array Length {srcBitArray.Length}.");
            }

            if (dstPos + numBits > dstBitArray.Length)
            {
                throw new ArgumentException($"BitArray invalid arguments: Out of bounds - destination position {dstPos}, numBits {numBits}, destination bit array Length {dstBitArray.Length}.");
            }
        }
    }

    sealed class UnsafeBitArrayDebugView
    {
        UnsafeBitArray Data;

        public UnsafeBitArrayDebugView(UnsafeBitArray data)
        {
            Data = data;
        }

        public bool[] Bits
        {
            get
            {
                var array = new bool[Data.Length];
                for (int i = 0; i < Data.Length; ++i)
                {
                    array[i] = Data.IsSet(i);
                }
                return array;
            }
        }
    }
}