// ----------------------------------------------------------------------------
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ----------------------------------------------------------------------------

using System;

namespace Smb.Shared
{
#if ENABLE_GENERICS
    public struct ArraySpan<T>
    {
        readonly T[]! _array;
        readonly int _offset;
        readonly int _length;

        public ArraySpan(T[]! array, int offset, int length)
        {
            if (array == null)
                throw new ArgumentNullException("array");
            if (offset < 0)
                throw new ArgumentException("Offset cannot be negative");
            if (length < 0)
                throw new ArgumentException("Length cannot be negative");
            if (offset + length > array.Length)
                throw new ArgumentException("Offset and length identify an array span that exceeds the length of the input array.");

            _array = array;
            _offset = offset;
            _length = length;
        }

        public ArraySpan(T[]! array)
            : this(array, 0, array.Length)
        {
        }


        public static implicit operator ArraySpan<T>(T[]! array)
        {
            return new ArraySpan<T>(array, 0, array.Length);
        }


        public T this[int index]
        {
            get
            {
                if (index < 0 || index >= _length)
                    throw new ArgumentOutOfRangeException("index");
                return _array[_offset + index];
            }

            set
            {
                if (index < 0 || index >= _length)
                    throw new ArgumentOutOfRangeException("index");
                _array[_offset + index] = value;
            }
        }

        public int Length
        {
            get { return _length; }
        }

        public int Offset
        {
            get { return _offset; }
        }

        public T[]! ContainingArray
        {
            get { return _array; }
        }

        public override string! ToString()
        {
            return "[ArraySpan<" + typeof(T).Name + "> offset " + _offset + " length " + _length + "]";
        }
    }
#else
    public struct ArraySpan_byte
    {
        readonly byte[]! _array;
        readonly int _offset;
        readonly int _length;

        public ArraySpan_byte(byte[]! array, int offset, int length)
        {
            if (array == null)
                throw new ArgumentNullException("array");
            if (offset < 0)
                throw new ArgumentException("Offset cannot be negative");
            if (length < 0)
                throw new ArgumentException("Length cannot be negative");
            if (offset + length > array.Length)
                throw new ArgumentException("Offset and length identify an array span that exceeds the length of the input array.");

            _array = array;
            _offset = offset;
            _length = length;
        }

        public ArraySpan_byte(byte[]! array)
            : this(array, 0, array.Length)
        {
        }


        public static implicit operator ArraySpan_byte(byte[]! array)
        {
            return new ArraySpan_byte(array, 0, array.Length);
        }


        public byte this[int index]
        {
            get
            {
                if (index < 0 || index >= _length)
                    throw new ArgumentOutOfRangeException("index");
                return _array[_offset + index];
            }

            set
            {
                if (index < 0 || index >= _length)
                    throw new ArgumentOutOfRangeException("index");
                _array[_offset + index] = value;
            }
        }

        public int Length
        {
            get { return _length; }
        }

        public int Offset
        {
            get { return _offset; }
        }

        public byte[]! ContainingArray
        {
            get { return _array; }
        }

        public override string! ToString()
        {
            return "[ArraySpan<byte> offset " + _offset + " length " + _length + "]";
        }
    }
#endif

}