// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Net.Http;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.OAuth;
using Microsoft.AspNetCore.DataProtection;
using Microsoft.Extensions.Options;
 
namespace Microsoft.Extensions.DependencyInjection;
 
/// <summary>
/// Used to setup defaults for the OAuthOptions.
/// </summary>
public class OAuthPostConfigureOptions<TOptions, THandler> : IPostConfigureOptions<TOptions>
    where TOptions : OAuthOptions, new()
    where THandler : OAuthHandler<TOptions>
{
    private readonly IDataProtectionProvider _dp;
 
    /// <summary>
    /// Initializes the <see cref="OAuthPostConfigureOptions{TOptions, THandler}"/>.
    /// </summary>
    /// <param name="dataProtection">The <see cref="IDataProtectionProvider"/>.</param>
    public OAuthPostConfigureOptions(IDataProtectionProvider dataProtection)
    {
        _dp = dataProtection;
    }
 
    /// <inheritdoc />
    public void PostConfigure(string? name, TOptions options)
    {
        ArgumentNullException.ThrowIfNull(name);
 
        options.DataProtectionProvider = options.DataProtectionProvider ?? _dp;
        if (options.Backchannel == null)
        {
            options.Backchannel = new HttpClient(options.BackchannelHttpHandler ?? new HttpClientHandler());
            options.Backchannel.DefaultRequestHeaders.UserAgent.ParseAdd("Microsoft ASP.NET Core OAuth handler");
            options.Backchannel.Timeout = options.BackchannelTimeout;
            options.Backchannel.MaxResponseContentBufferSize = 1024 * 1024 * 10; // 10 MB
        }
 
        if (options.StateDataFormat == null)
        {
            var dataProtector = options.DataProtectionProvider.CreateProtector(
                typeof(THandler).FullName!, name, "v1");
            options.StateDataFormat = new PropertiesDataFormat(dataProtector);
        }
    }
}