// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics.CodeAnalysis;
using Microsoft.AspNetCore.HeaderParsing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Shared.Diagnostics;
 
namespace Microsoft.AspNetCore.Http;
 
/// <summary>
/// Extensions for header parsing.
/// </summary>
public static class HeaderParsingHttpRequestExtensions
{
    /// <summary>
    /// Gets the header parsing feature to access parsed header values.
    /// </summary>
    /// <param name="request">The <see cref="HttpRequest"/> instance.</param>
    /// <returns>The value of <paramref name="request"/>.</returns>
    public static HeaderParsingFeature GetHeaderParsing(this HttpRequest request)
    {
        var context = Throw.IfNull(request).HttpContext;
 
        var feature = context.Features.Get<HeaderParsingFeature>();
 
        if (feature is null)
        {
            feature = context.RequestServices.GetRequiredService<HeaderParsingFeature>();
            feature.Context = context;
            context.Features.Set(feature);
        }
 
        return feature;
    }
 
    /// <summary>
    /// Tries to get a header value if it exists and can be parsed.
    /// </summary>
    /// <typeparam name="T">The type of the header value.</typeparam>
    /// <param name="request">The <see cref="HttpRequest"/> instance.</param>
    /// <param name="header">The header to parse.</param>
    /// <param name="value">A resulting value.</param>
    /// <returns><see langword="true"/> if the header value was successfully fetched parsed.</returns>
    public static bool TryGetHeaderValue<T>(this HttpRequest request, HeaderKey<T> header, [NotNullWhen(true)] out T? value)
        where T : notnull
    {
        return Throw.IfNull(request)
            .GetHeaderParsing()
            .TryGetHeaderValue(Throw.IfNull(header), out value);
    }
 
    /// <summary>
    /// Tries to get a header value if it exists and can be parsed.
    /// </summary>
    /// <typeparam name="T">The type of the header value.</typeparam>
    /// <param name="request">The <see cref="HttpRequest"/> instance.</param>
    /// <param name="header">The header to parse.</param>
    /// <param name="value">A resulting value.</param>
    /// <param name="result">Details on the parsing operation.</param>
    /// <returns><see langword="true"/> if the header value was successfully fetched parsed.</returns>
    public static bool TryGetHeaderValue<T>(this HttpRequest request, HeaderKey<T> header, [NotNullWhen(true)] out T? value, out ParsingResult result)
        where T : notnull
    {
        return Throw.IfNull(request)
            .GetHeaderParsing()
            .TryGetHeaderValue(Throw.IfNull(header), out value, out result);
    }
}