using System;
using System.Collections.Generic;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using ServiceStack.Configuration;
using ServiceStack.Text;
using ServiceStack.Web;

namespace ServiceStack.Auth;

/// <summary>
///   Create Odnoklassniki App at: http://www.odnoklassniki.ru/devaccess
///   The Callback URL for your app should match the CallbackUrl provided.
///   
///   NB: They claim they use OAuth 2.0, but they in fact don't. 
///   http://apiok.ru/wiki/display/api/Authorization+OAuth+2.0
/// </summary>
public class OdnoklassnikiAuthProvider : OAuthProvider
{
    public const string Name = "odnoklassniki";
    public static string Realm = "http://www.odnoklassniki.ru/oauth/";
    public static string PreAuthUrl = "http://www.odnoklassniki.ru/oauth/authorize";
    public static string TokenUrl = "http://api.odnoklassniki.ru/oauth/token.do";

    static OdnoklassnikiAuthProvider() {}

    public OdnoklassnikiAuthProvider(IAppSettings appSettings)
        : base(appSettings, Realm, Name, "ApplicationId", "SecretKey")
    {
        ApplicationId = appSettings.GetString("oauth.Odnoklassniki.ApplicationId");
        PublicKey = appSettings.GetString("oauth.Odnoklassniki.PublicKey");
        SecretKey = appSettings.GetString("oauth.Odnoklassniki.SecretKey");
        AccessTokenUrl = TokenUrl;

        NavItem = new NavItem {
            Href = "/auth/" + Name,
            Label = "Sign In with Odnoklassniki",
            Id = "btn-" + Name,
            ClassName = "btn-social btn-odnoklassniki",
            IconClass = "fab svg-odnoklassniki",
        };
    }

    public string ApplicationId { get; set; }
    public string PublicKey { get; set; }
    public string SecretKey { get; set; }

    public override async Task<object> AuthenticateAsync(IServiceBase authService, IAuthSession session, Authenticate request, CancellationToken token = default)
    {
        IAuthTokens tokens = Init(authService, ref session, request);
        var ctx = CreateAuthContext(authService, session, tokens);
        IRequest httpRequest = authService.Request;


        string error = httpRequest.QueryString["error"];

        bool hasError = !error.IsNullOrEmpty();
        if (hasError)
        {
            Log.Error($"Odnoklassniki error callback. {httpRequest.QueryString}");
            return authService.Redirect(FailedRedirectUrlFilter(ctx, session.ReferrerUrl.SetParam("f", error)));
        }

        string code = httpRequest.QueryString["code"];
        bool isPreAuthCallback = !code.IsNullOrEmpty();
        if (!isPreAuthCallback)
        {
            string preAuthUrl = $"{PreAuthUrl}?client_id={ApplicationId}&redirect_uri={CallbackUrl.UrlEncode()}&response_type=code&layout=m";

            await this.SaveSessionAsync(authService, session, SessionExpiry, token).ConfigAwait();
            return authService.Redirect(PreAuthUrlFilter(ctx, preAuthUrl));
        }

        try
        {
            string payload = $"client_id={ApplicationId}&client_secret={SecretKey}&code={code}&redirect_uri={CallbackUrl.UrlEncode()}&grant_type=authorization_code";

            string contents = await AccessTokenUrlFilter(ctx, AccessTokenUrl)
                .PostToUrlAsync(formData:payload, requestFilter:req => 
                        req.With(c => {
                            c.UserAgent = ServiceClientBase.DefaultUserAgent;
                            c.Accept = "*/*";
                        }), 
                    token: token).ConfigAwait();

            var authInfo = JsonObject.Parse(contents);

            //ok.ru does not throw exception, but returns error property in JSON response
            string accessTokenError = authInfo.Get("error");

            if (!accessTokenError.IsNullOrEmpty())
            {
                Log.Error($"Odnoklassniki access_token error callback. {authInfo}");
                return authService.Redirect(session.ReferrerUrl.SetParam("f", "AccessTokenFailed"));
            }
            tokens.AccessTokenSecret = authInfo.Get("access_token");
            tokens.UserId = authInfo.Get("user_id");

            session.IsAuthenticated = true;

            return await OnAuthenticatedAsync(authService, session, tokens, authInfo.ToDictionary(), token).ConfigAwait()
                   ?? await authService.Redirect(SuccessRedirectUrlFilter(ctx, session.ReferrerUrl.SetParam("s", "1"))).SuccessAuthResultAsync(authService,session).ConfigAwait();
        }
        catch (Exception ex)
        {
            //just in case it starts throwing exceptions 
            var statusCode = ex.GetStatus();
            if (statusCode == HttpStatusCode.BadRequest)
            {
                return authService.Redirect(FailedRedirectUrlFilter(ctx, session.ReferrerUrl.SetParam("f", "AccessTokenFailed")));
            }
        }
        return authService.Redirect(FailedRedirectUrlFilter(ctx, session.ReferrerUrl.SetParam("f", "Unknown")));
    }

    protected override async Task LoadUserAuthInfoAsync(AuthUserSession userSession, IAuthTokens tokens, Dictionary<string, string> authInfo, CancellationToken token = default)
    {
        try
        {
            //sig = md5( request_params_composed_string + md5(access_token + application_secret_key)  )
            string innerSignature = Encoding.UTF8.GetBytes(tokens.AccessTokenSecret + ConsumerSecret).ToMd5Hash();
            string signature = Encoding.UTF8.GetBytes($"application_key={PublicKey}" + innerSignature).ToMd5Hash();

            string payload = $"access_token={tokens.AccessTokenSecret}&sig={signature}&application_key={PublicKey}";

            string json = await "http://api.odnoklassniki.ru/api/users/getCurrentUser"
                .PostToUrlAsync(formData:payload, requestFilter:req => 
                        req.With(c => {
                            c.UserAgent = ServiceClientBase.DefaultUserAgent;
                            c.Accept = "*/*";
                        }), 
                    token: token).ConfigAwait();

            JsonObject obj = JsonObject.Parse(json);

            if (!obj.Get("error").IsNullOrEmpty())
            {
                Log.Error($"Could not retrieve Odnoklassniki user info for '{tokens.DisplayName}', Response:{json}");
                return;
            }

            //response fields info: http://apiok.ru/wiki/display/api/users.getCurrentUser+ru
            var location = JsonObject.Parse(obj.GetUnescaped("location"));

            tokens.UserId = obj.Get("uid");
            tokens.DisplayName = obj.Get("name");
            tokens.FirstName = obj.Get("first_name");
            tokens.LastName = obj.Get("last_name");
            tokens.BirthDateRaw = obj.Get("birthday");
            tokens.Language = obj.Get("locale");
            tokens.Country = location.Get("countryCode");
            tokens.City = location.Get("city");
            tokens.Gender = obj.Get("gender");

            if (SaveExtendedUserInfo)
            {
                obj.Each(x => authInfo[x.Key] = x.Value);
            }
        }
        catch (Exception ex)
        {
            Log.Error($"Could not retrieve Odnoklassniki user info for '{tokens.DisplayName}'", ex);
        }

        await LoadUserOAuthProviderAsync(userSession, tokens).ConfigAwait();
    }

    public override Task LoadUserOAuthProviderAsync(IAuthSession authSession, IAuthTokens tokens)
    {
        if (authSession is AuthUserSession userSession)
        {
            userSession.DisplayName = tokens.DisplayName ?? userSession.DisplayName;
            userSession.FirstName = tokens.FirstName ?? userSession.DisplayName;
            userSession.LastName = tokens.LastName ?? userSession.LastName;
            userSession.BirthDateRaw = tokens.BirthDateRaw ?? userSession.BirthDateRaw;
            userSession.Language = tokens.Language ?? userSession.Language;
            userSession.Country = tokens.Country ?? userSession.Country;
            userSession.City = tokens.City ?? userSession.City;
            userSession.Gender = tokens.Gender ?? userSession.Gender;
        }
        return Task.CompletedTask;
    }
}

#region Test APP Registration Information Email
/*
From: "odnoklassniki.ru" <bezotveta@odnoklassniki.ru>
To: rouslan@gmail.com
Message-ID: <1462956089.11400671017663.JavaMail.root@srvk849.odnoklassniki.ru>
Subject: =?KOI8-R?B?T2Rub2tsYXNzbmlraS5ydTog98HbxSDQ0g==?=
=?KOI8-R?B?yczP1sXOycUg2sHSxcfJ09TSydLP18HOzw==?=

Ваше приложение ServiceStack Test Login успешно зарегистрировано на Odnoklassniki.ru.

Application ID: 1089990656.
Публичный ключ приложения: CBABPIPBEBABABABA.
Секретный ключ приложения:  B268138DF0BE3919FB1BBED8.
Ссылка на приложение: http://www.odnoklassniki.ru/games/servicestacktestlogin
Этот ключ необходим для изменения настроек приложения и для подписи/верификации запросов от Вашего приложения. Более подробная информация содержится в документации к програмному интерфейсу сайта Odnoklassniki.ru.
--
С уважением,
Служба поддержки Odnoklassniki.ru

*/
#endregion