using Google.Apis.Auth.OAuth2;
using Google.Apis.Util.Store;
using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

public static class GmailTokenManager
{
    //public static async Task<string> ObtenerAccessTokenAsync(GmailConfig config)
    //{
    //    var stream = new MemoryStream(config.ClientSecret);

    //    var credencial = await GoogleWebAuthorizationBroker.AuthorizeAsync(
    //      GoogleClientSecrets.FromStream(stream).Secrets,
    //      new[] { "https://mail.google.com/" },
    //      config.Usuario,
    //      CancellationToken.None,
    //      new FileDataStore(config.TokenFolder, true)
    //  );

    //    return await credencial.GetAccessTokenForRequestAsync();
    //}
    private static readonly SemaphoreSlim _tokenSemaphore = new SemaphoreSlim(1, 1);

    public static async Task<string> ObtenerAccessTokenAsync(GmailConfig config)
    {
        var stream = new MemoryStream(config.ClientSecret);
        int i = 0;  
        do
        {
            i++;
            await _tokenSemaphore.WaitAsync();
            try
            {
                var credencial = await GoogleWebAuthorizationBroker.AuthorizeAsync(
                    GoogleClientSecrets.FromStream(stream).Secrets,
                    new[] { "https://mail.google.com/" },
                    config.Usuario,
                    CancellationToken.None,
                    new FileDataStore(config.TokenFolder, true)
                );

                return await credencial.GetAccessTokenForRequestAsync();              
            }
            catch (Exception ex)
            {
                if (i > 1) throw new Exception(ex.Message,ex);
                System.Threading.Thread.Sleep(5000);
            }
            finally
            {
                _tokenSemaphore.Release();
            }           
        }
        while (true);
    }
}