using Google.Apis.Auth.OAuth2;
using Google.Apis.Auth.OAuth2.Flows;
using Google.Apis.Auth.OAuth2.Responses;
using Google.Apis.Drive.v3;
using Google.Apis.Services;
using Google.Apis.Util.Store;
using System;
using System.ComponentModel;
using System.Windows.Input;
using Xamarin.Auth;
using Xamarin.Auth.Presenters;
using Xamarin.Forms;

public class GoogleViewModel: INotifyPropertyChanged
    {
        private string scope = "https://www.googleapis.com/auth/drive.file";
        private string clientId = "your client id here";
        private string redirectUrl = "xamarin.test.driverest:/oauth2redirect";

        public event PropertyChangedEventHandler PropertyChanged;

        public ICommand OnGoogleDrive { get; set; }

        public GoogleViewModel()
        {
            var auth = new OAuth2Authenticator(
              this.clientId,
              string.Empty,
              scope,
              new Uri("https://accounts.google.com/o/oauth2/v2/auth"),
              new Uri(redirectUrl),
              new Uri("https://www.googleapis.com/oauth2/v4/token"),
              isUsingNativeUI: true);
            AuthenticatorHelper.OAuth2Authenticator = auth;
            auth.Completed += async (sender, e) =>
            {
                if (e.IsAuthenticated)
                {

                    var initializer = new GoogleAuthorizationCodeFlow.Initializer
                    {
                        ClientSecrets = new Google.Apis.Auth.OAuth2.ClientSecrets()
                        {
                            ClientId = clientId,
                        }
                    };
                    initializer.Scopes = new[] { scope };
                    initializer.DataStore = new FileDataStore("Google.Apis.Auth");
                    var flow = new GoogleAuthorizationCodeFlow(initializer);
                    var user = "DriveTest";
                    var token = new TokenResponse()
                    {
                        AccessToken = e.Account.Properties["access_token"],
                        ExpiresInSeconds = Convert.ToInt64(e.Account.Properties["expires_in"]),
                        RefreshToken = e.Account.Properties["refresh_token"],
                        Scope = e.Account.Properties["scope"],
                        TokenType = e.Account.Properties["token_type"]
                    };
                    UserCredential userCredential = new UserCredential(flow, user, token);
                    var driveService = new DriveService(new BaseClientService.Initializer()
                    {
                        HttpClientInitializer = userCredential,
                        ApplicationName = "XamarinDriveTest",
                    });


                    //test google drive
                    DriveServiceHelper helper = new DriveServiceHelper(driveService);
                    var id = await helper.CreateFile();
                    await helper.SaveFile(id, "test", "test save content");
                    var content = await helper.ReadFile(id);
                }
            };
            auth.Error += (sender, e) =>
            {

            };

            this.OnGoogleDrive = new Command(() =>
            {
                var presenter = new OAuthLoginPresenter();
                presenter.Login(auth);
            });
        }
    }
    public static class AuthenticatorHelper
    {
        public static OAuth2Authenticator OAuth2Authenticator { get; set; }
    }