// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable enable
 
using System.Diagnostics;
using System.Runtime.CompilerServices;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
 
namespace Microsoft.AspNetCore.Http;
 
/// <summary>
/// A factory for creating <see cref="HttpContext" /> instances.
/// </summary>
public class DefaultHttpContextFactory : IHttpContextFactory
{
    private readonly IHttpContextAccessor? _httpContextAccessor;
    private readonly FormOptions _formOptions;
    private readonly IServiceScopeFactory _serviceScopeFactory;
 
    // This takes the IServiceProvider because it needs to support an ever expanding
    // set of services that flow down into HttpContext features
    /// <summary>
    /// Creates a factory for creating <see cref="HttpContext" /> instances.
    /// </summary>
    /// <param name="serviceProvider">The <see cref="IServiceProvider"/> to be used when retrieving services.</param>
    public DefaultHttpContextFactory(IServiceProvider serviceProvider)
    {
        // May be null
        _httpContextAccessor = serviceProvider.GetService<IHttpContextAccessor>();
        _formOptions = serviceProvider.GetRequiredService<IOptions<FormOptions>>().Value;
        _serviceScopeFactory = serviceProvider.GetRequiredService<IServiceScopeFactory>();
    }
 
    internal IHttpContextAccessor? HttpContextAccessor => _httpContextAccessor;
 
    /// <summary>
    /// Create an <see cref="HttpContext"/> instance given an <paramref name="featureCollection" />.
    /// </summary>
    /// <param name="featureCollection"></param>
    /// <returns>An initialized <see cref="HttpContext"/> object.</returns>
    public HttpContext Create(IFeatureCollection featureCollection)
    {
        ArgumentNullException.ThrowIfNull(featureCollection);
 
        var httpContext = new DefaultHttpContext(featureCollection);
        Initialize(httpContext, featureCollection);
        return httpContext;
    }
 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    internal void Initialize(DefaultHttpContext httpContext, IFeatureCollection featureCollection)
    {
        Debug.Assert(featureCollection != null);
        Debug.Assert(httpContext != null);
 
        httpContext.Initialize(featureCollection);
 
        if (_httpContextAccessor != null)
        {
            _httpContextAccessor.HttpContext = httpContext;
        }
 
        httpContext.FormOptions = _formOptions;
        httpContext.ServiceScopeFactory = _serviceScopeFactory;
    }
 
    /// <summary>
    /// Clears the current <see cref="HttpContext" />.
    /// </summary>
    public void Dispose(HttpContext httpContext)
    {
        if (_httpContextAccessor != null)
        {
            _httpContextAccessor.HttpContext = null;
        }
    }
 
    internal void Dispose(DefaultHttpContext httpContext)
    {
        if (_httpContextAccessor != null)
        {
            _httpContextAccessor.HttpContext = null;
        }
 
        httpContext.Uninitialize();
    }
}