// Copyright (c) Microsoft Open Technologies, Inc. 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.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Net.Http;
using Microsoft.AspNet.Authentication.DataHandler;
using Microsoft.AspNet.Authentication.DataHandler.Encoder;
using Microsoft.AspNet.Authentication.Twitter.Messages;
using Microsoft.AspNet.Builder;
using Microsoft.AspNet.DataProtection;
using Microsoft.Framework.Internal;
using Microsoft.Framework.Logging;
using Microsoft.Framework.OptionsModel;
using Microsoft.Framework.WebEncoders;

namespace Microsoft.AspNet.Authentication.Twitter
{
    /// <summary>
    /// ASP.NET middleware for authenticating users using Twitter
    /// </summary>
    [SuppressMessage("Microsoft.Design", "CA1001:TypesThatOwnDisposableFieldsShouldBeDisposable", Justification = "Middleware are not disposable.")]
    public class TwitterAuthenticationMiddleware : AuthenticationMiddleware<TwitterAuthenticationOptions>
    {
        private readonly HttpClient _httpClient;

        /// <summary>
        /// Initializes a <see cref="TwitterAuthenticationMiddleware"/>
        /// </summary>
        /// <param name="next">The next middleware in the HTTP pipeline to invoke</param>
        /// <param name="services"></param>
        /// <param name="dataProtectionProvider"></param>
        /// <param name="loggerFactory"></param>
        /// <param name="options">Configuration options for the middleware</param>
        public TwitterAuthenticationMiddleware(
            [NotNull] RequestDelegate next,
            [NotNull] IDataProtectionProvider dataProtectionProvider,
            [NotNull] ILoggerFactory loggerFactory,
            [NotNull] IUrlEncoder encoder,
            [NotNull] IOptions<ExternalAuthenticationOptions> externalOptions,
            [NotNull] IOptions<TwitterAuthenticationOptions> options,
            ConfigureOptions<TwitterAuthenticationOptions> configureOptions = null)
            : base(next, options, loggerFactory, encoder, configureOptions)
        {
            if (string.IsNullOrWhiteSpace(Options.ConsumerSecret))
            {
                throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, Resources.Exception_OptionMustBeProvided, "ConsumerSecret"));
            }
            if (string.IsNullOrWhiteSpace(Options.ConsumerKey))
            {
                throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, Resources.Exception_OptionMustBeProvided, "ConsumerKey"));
            }

            if (Options.Notifications == null)
            {
                Options.Notifications = new TwitterAuthenticationNotifications();
            }
            if (Options.StateDataFormat == null)
            {
                IDataProtector dataProtector = dataProtectionProvider.CreateProtector(
                    typeof(TwitterAuthenticationMiddleware).FullName, Options.AuthenticationScheme, "v1");
                Options.StateDataFormat = new SecureDataFormat<RequestToken>(
                    Serializers.RequestToken,
                    dataProtector,
                    TextEncodings.Base64Url);
            }

            if (string.IsNullOrEmpty(Options.SignInScheme))
            {
                Options.SignInScheme = externalOptions.Options.SignInScheme;
            }
            if (string.IsNullOrEmpty(Options.SignInScheme))
            {
                throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, Resources.Exception_OptionMustBeProvided, "SignInScheme"));
            }

            _httpClient = new HttpClient(ResolveHttpMessageHandler(Options));
            _httpClient.Timeout = Options.BackchannelTimeout;
            _httpClient.MaxResponseContentBufferSize = 1024 * 1024 * 10; // 10 MB
            _httpClient.DefaultRequestHeaders.Accept.ParseAdd("*/*");
            _httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("Microsoft ASP.NET Twitter middleware");
            _httpClient.DefaultRequestHeaders.ExpectContinue = false;
        }

        /// <summary>
        /// Provides the <see cref="AuthenticationHandler"/> object for processing authentication-related requests.
        /// </summary>
        /// <returns>An <see cref="AuthenticationHandler"/> configured with the <see cref="TwitterAuthenticationOptions"/> supplied to the constructor.</returns>
        protected override AuthenticationHandler<TwitterAuthenticationOptions> CreateHandler()
        {
            return new TwitterAuthenticationHandler(_httpClient);
        }

        [SuppressMessage("Microsoft.Reliability", "CA2000:Dispose objects before losing scope", Justification = "Managed by caller")]
        private static HttpMessageHandler ResolveHttpMessageHandler(TwitterAuthenticationOptions options)
        {
            HttpMessageHandler handler = options.BackchannelHttpHandler ??
#if DNX451
                new WebRequestHandler();
            // If they provided a validator, apply it or fail.
            if (options.BackchannelCertificateValidator != null)
            {
                // Set the cert validate callback
                var webRequestHandler = handler as WebRequestHandler;
                if (webRequestHandler == null)
                {
                    throw new InvalidOperationException(Resources.Exception_ValidatorHandlerMismatch);
                }
                webRequestHandler.ServerCertificateValidationCallback = options.BackchannelCertificateValidator.Validate;
            }
#else
                new WinHttpHandler();
#endif
            return handler;
        }
    }
}