// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Linq;
using System.Numerics;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
using Xunit;

namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
{
    public class UTF8DecodingTests
    {
        [Theory]
        [InlineData(new byte[] { 0x01 })] // 1 byte: Control character, lowest UTF-8 character we will allow to be decoded since 0x00 is rejected,
        [InlineData(new byte[] { 0xc2, 0xa0})] // 2 bytes: Non-breaking space, lowest valid UTF-8 that is not a valid ASCII character
        [InlineData(new byte[] { 0xef, 0xbf, 0xbd })] // 3 bytes: Replacement character, highest UTF-8 character currently encoded in the UTF-8 code page
        private void FullUTF8RangeSupported(byte[] encodedBytes)
        {
            var s = encodedBytes.AsSpan().GetAsciiOrUTF8StringNonNullCharacters();

            Assert.Equal(1, s.Length);
        }

        [Theory]
        [InlineData(new byte[] { 0x00 })] // We reject the null character
        [InlineData(new byte[] { 0x80 })] // First valid Extended ASCII that is not a valid UTF-8 Encoding
        [InlineData(new byte[] { 0x20, 0xac })] // First valid Extended ASCII that is not a valid UTF-8 Encoding
        private void ExceptionThrownForZeroOrNonAscii(byte[] bytes)
        {
            for (var length = bytes.Length; length < Vector<sbyte>.Count * 4 + bytes.Length; length++)
            {
                for (var position = 0; position <= length - bytes.Length; position++)
                {
                    var byteRange = Enumerable.Range(1, length).Select(x => (byte)x).ToArray();
                    Array.Copy(bytes, 0, byteRange, position, bytes.Length);

                    Assert.Throws<InvalidOperationException>(() => byteRange.AsSpan().GetAsciiOrUTF8StringNonNullCharacters());
                }
            }
        }
    }
}