// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http3;
 
namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests;
 
public class Http3QPackEncoderTests
{
    [Fact]
    public void BeginEncodeHeaders_StatusWithoutIndexedValue_WriteIndexNameAndFullValue()
    {
        Span<byte> buffer = new byte[1024 * 16];
 
        var totalHeaderSize = 0;
        var headers = new HttpResponseHeaders();
        var enumerator = new Http3HeadersEnumerator();
        enumerator.Initialize(headers);
 
        Assert.True(QPackHeaderWriter.BeginEncodeHeaders(418, enumerator, buffer, ref totalHeaderSize, out var length));
 
        var result = buffer.Slice(0, length).ToArray();
        var hex = BitConverter.ToString(result);
        Assert.Equal("00-00-5F-30-03-34-31-38", hex);
    }
 
    [Fact]
    public void BeginEncodeHeaders_StatusWithIndexedValue_WriteIndex()
    {
        Span<byte> buffer = new byte[1024 * 16];
 
        var totalHeaderSize = 0;
        var headers = new HttpResponseHeaders();
        var enumerator = new Http3HeadersEnumerator();
        enumerator.Initialize(headers);
 
        Assert.True(QPackHeaderWriter.BeginEncodeHeaders(200, enumerator, buffer, ref totalHeaderSize, out var length));
 
        var result = buffer.Slice(0, length).ToArray();
        var hex = BitConverter.ToString(result);
        Assert.Equal("00-00-D9", hex);
    }
 
    [Theory]
    [InlineData(103)]
    [InlineData(200)]
    [InlineData(304)]
    [InlineData(404)]
    [InlineData(503)]
    [InlineData(100)]
    [InlineData(204)]
    [InlineData(206)]
    [InlineData(302)]
    [InlineData(400)]
    [InlineData(403)]
    [InlineData(421)]
    [InlineData(425)]
    [InlineData(500)]
    public void BeginEncodeHeaders_StatusWithIndexedValue_ExpectedLength(int statusCode)
    {
        Span<byte> buffer = new byte[1024 * 16];
 
        var totalHeaderSize = 0;
        var headers = new HttpResponseHeaders();
        var enumerator = new Http3HeadersEnumerator();
        enumerator.Initialize(headers);
 
        Assert.True(QPackHeaderWriter.BeginEncodeHeaders(statusCode, enumerator, buffer, ref totalHeaderSize, out var length));
        length -= 2; // Remove prefix
 
        Assert.True(length <= 2, "Indexed header should be encoded into 1 or 2 bytes");
    }
 
    [Fact]
    public void BeginEncodeHeaders_StaticKeyAndValue_WriteIndex()
    {
        Span<byte> buffer = new byte[1024 * 16];
 
        var headers = (IHeaderDictionary)new HttpResponseHeaders();
        headers.ContentType = "application/json";
 
        var totalHeaderSize = 0;
        var enumerator = new Http3HeadersEnumerator();
        enumerator.Initialize(headers);
 
        Assert.True(QPackHeaderWriter.BeginEncodeHeaders(enumerator, buffer, ref totalHeaderSize, out var length));
 
        var result = buffer.Slice(2, length - 2).ToArray(); // trim prefix
        var hex = BitConverter.ToString(result);
        Assert.Equal("EE", hex);
    }
 
    [Fact]
    public void BeginEncodeHeaders_NonStaticKey_WriteFullNameAndFullValue()
    {
        Span<byte> buffer = new byte[1024 * 16];
 
        var headers = (IHeaderDictionary)new HttpResponseHeaders();
        headers.Translate = "private";
 
        var totalHeaderSize = 0;
        var enumerator = new Http3HeadersEnumerator();
        enumerator.Initialize(headers);
 
        Assert.True(QPackHeaderWriter.BeginEncodeHeaders(enumerator, buffer, ref totalHeaderSize, out var length));
 
        var result = buffer.Slice(2, length - 2).ToArray(); // trim prefix
        var hex = BitConverter.ToString(result);
        Assert.Equal("37-02-74-72-61-6E-73-6C-61-74-65-07-70-72-69-76-61-74-65", hex);
    }
 
    [Fact]
    public void BeginEncodeHeaders_NonStaticKey_WriteFullNameAndFullValue_CustomHeader()
    {
        Span<byte> buffer = new byte[1024 * 16];
 
        var headers = (IHeaderDictionary)new HttpResponseHeaders();
        headers["new-header"] = "value";
 
        var totalHeaderSize = 0;
        var enumerator = new Http3HeadersEnumerator();
        enumerator.Initialize(headers);
 
        Assert.True(QPackHeaderWriter.BeginEncodeHeaders(enumerator, buffer, ref totalHeaderSize, out var length));
 
        var result = buffer.Slice(2, length - 2).ToArray(); // trim prefix
        var hex = BitConverter.ToString(result);
        Assert.Equal("37-03-6E-65-77-2D-68-65-61-64-65-72-05-76-61-6C-75-65", hex);
    }
 
    [Fact]
    public void BeginEncodeHeaders_StaticKey_WriteStaticNameAndFullValue()
    {
        Span<byte> buffer = new byte[1024 * 16];
 
        var headers = (IHeaderDictionary)new HttpResponseHeaders();
        headers.ContentType = "application/custom";
 
        var totalHeaderSize = 0;
        var enumerator = new Http3HeadersEnumerator();
        enumerator.Initialize(headers);
 
        Assert.True(QPackHeaderWriter.BeginEncodeHeaders(enumerator, buffer, ref totalHeaderSize, out var length));
 
        var result = buffer.Slice(2, length - 2).ToArray();
        var hex = BitConverter.ToString(result);
        Assert.Equal("5F-1D-12-61-70-70-6C-69-63-61-74-69-6F-6E-2F-63-75-73-74-6F-6D", hex);
    }
}