What is Telebot

Telebot is a well documented .NET client library for the Telegram Bot API client written completely in C#.

Where can I get it?

First, install NuGet. Then, install Telebot from the package manager console:

PM> Install-Package Telebot

How can I use it?

For Persian (Farsi) how-to guide, please visit my blog.

Simply instantiate Telebot class and use available methods. Telebot internally uses HttpClient so, it is recommended not to dispose it after every request. I suggest to read the Lifecycle section of the Designing Evolvable Web APIs with ASP.NET.

// Provides a base class for communicating with Telegram Bot API servers.
private readonly Telebot _telebot = new Telebot("123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11");

public async Task RunAsync()
{
    // Used for getting only the unconfirmed updates.
    // It is recommended to stored this value between sessions. 
    // More information at https://core.telegram.org/bots/api#getting-updates
    var offset = 0L;

    while( true )
    {
        // Use this method to receive incoming updates using long polling.
        // Or use Telebot.SetWebhook() method to specify a URL to receive incoming updates.
        List<Update> updates = (await this._telebot.GetUpdatesAsync(offset).ConfigureAwait(false)).ToList();
        if( updates.Any() )
        {
            offset = updates.Max(u => u.Id) + 1;

            foreach( Update update in updates )
            {
                switch( update.Type )
                {
                    case UpdateType.Message:
                        await this.CheckMessagesAsync(update.Message).ConfigureAwait(false);
                        break;
                    case UpdateType.InlineQuery:
                        await this.CheckInlineQueryAsync(update).ConfigureAwait(false);
                        break;
                    case UpdateType.ChosenInlineResult:
                        this.CheckChosenInlineResult(update);
                        break;
                    default:
                        throw new ArgumentOutOfRangeException();
                }
            }
        }

        await Task.Delay(TimeSpan.FromSeconds(1)).ConfigureAwait(false);
    }
}

private async Task CheckMessagesAsync(Message message)
{
    // Assume we are doing more than echoing stuff.
    if( message == null )
        return;

    // This method will tell the user that something is happening on the bot's side.
    // It is recommended to use this method when a response from the bot 
    // will take a noticeable amount of time to arrive.
    await this._telebot.SendChatActionAsync(message.Chat.Id, ChatAction.Typing).ConfigureAwait(false);
    await Task.Delay(TimeSpan.FromSeconds(3)).ConfigureAwait(false);

    // This method will send a text message (obviously).
    await this._telebot.SendMessageAsync(message.Chat.Id, message.Text ?? "Hmmmm").ConfigureAwait(false);
}

private async Task CheckInlineQueryAsync(Update update)
{
    // Telebot will support all 19 types of InlineQueryResult.
    // To see available inline query results:
    // https://core.telegram.org/bots/api#answerinlinequery
    var articleResult = new InlineQueryResultArticle
    {
        Id = Guid.NewGuid().ToString("N"),
        Title = "This is a title",
        Url = "https://core.telegram.org/bots/api#inlinequeryresultarticle"
    };
    
    var photoResult = new InlineQueryResultPhoto
    {
        Id = Guid.NewGuid().ToString("N"),
        Url = "https://telegram.org/file/811140636/1/hzUbyxse42w/4cd52d0464b44e1e5b",
        ThumbnailUrl = "https://telegram.org/file/811140636/1/hzUbyxse42w/4cd52d0464b44e1e5b"
    };
    
    
    var gifResult = new InlineQueryResultGif
    {
        Id = Guid.NewGuid().ToString("N"),
        Url = "http://i.giphy.com/ya4eevXU490Iw.gif",
        ThumbnailUrl = "http://i.giphy.com/ya4eevXU490Iw.gif"
    };
    
    var results = new InlineQueryResult[] { articleResult, photoResult, gifResult };
    await this._telebot.AnswerInlineQueryAsync(update.InlineQuery.Id, results).ConfigureAwait(false);
}

private void CheckChosenInlineResult(Update update)
{
    Console.WriteLine("Received ChosenInlineResult.");
}