TDLib for Dart (WIP)

A port of the Telegram Database Library (TDLib) for Dart.

Update (November 1, 2019)

The Dart team made a bunch of breaking changes to dart:ffi since I first made this so I've had to up the minimum required Dart SDK version from 2.6.0 to 2.6.0-dev.8.2. I've also had to upgrade the package:ffi version to 0.1.4 (which isn't on pub so I had to pull it straight from the git repo). Please upgrade your Dart SDK version accordingly! (You'll have to be on the dev channel.) Once dart:ffi becomes a stable feature, hopefully this won't be a problem :)

Motivation

Last year I wanted to make a Telegram client for Flutter, but at the time Dart didn't have an FFI and my only option was to use the JNI classes and use a method channel to query the Telegram servers, which would have been a huge pain in the ass. But on September 10th, 2019 the Dart team announced an FFI for Dart so I can finally make my Telegram app. Though I'll need to set up the interface with a library.

How To Use It

1: Building TDLib

You'll need to download and build TDLib yourself. You can figure out how to do that here (just select your OS, don't change the language option). It doesn't especially matter where you build it, as long as the path to the root directory of TDLib is passed to the TelegramClient().

2: Including This Project

As it's incomplete and requires a lot of setup, I'm not putting this on pub just yet. You have two basic options for using this.

1. Clone the repository and copy the lib directory into your own project folder.
2. (Recommended) Include the following in your pubspec.yaml file:

dependencies:
  #...
  tdlib:
    git: git://github/periodicaidan/dart_tdlib
  #...

3: Generating Reflectors

This library has a small reliance on reflection, which isn't allowed in Flutter because Flutter does "tree shaking" to eliminate unused classes, which wouldn't work if there is code that's dynamically parsed and run from strings, as it wouldn't be able to safely eliminate anything. So it makes use of reflectable, which generates static code ahead of time to work like dart:mirrors. But you will have to generate the reflectables yourself. To do this, you can use build runner.

Include the following in your package.yaml file:

dev_dependencies:
  #...
  build_runner: ^1.0.0
  #...

Then, make a build.yaml file with the following (or add the new parts to your existing build.yaml file):

targets:
  $default:
    builders:
      reflectable:
        generate_for:
          - path/to/file.dart
        options:
          formatted: true

Finaly run pub run build_runner build. It should only take a few seconds though reflectable has been having some issues recently with long build times.

4: Now You're Ready to Rock and Roll

The general structure of a program using this library is something like this:

// tdlib_ex.dart
import 'package:tdlib/tdlib.dart' as td;
import 'tdlib_ex.reflectable.dart';

Future main() async {
  initializeReflectable();

  final client = td.TelegramClient('path/to/td');

  client.defineTdlibParams(
    // There are other parameters but these four are required!
    apiId: apiId,
    apiHash: apiHash,
    deviceModel: 'PearPhone G1',
    systemVersion: 'PearOS 1.0',
  );
  
  try {
    // Get a stream to handle changes to the authorization state
    // Mind you, there are other authorization states and it's better to switch
    // over [state.runtimeType].
    client.authorizationState.listen((state) async {
      if (state is td.AuthorizationStateWaitTdlibParameters) {
        await client.send(td.SetTdlibParameters(client.tdlibParams));
      }
    });
    
    await for (final update in client.incoming()) {
      // Handle each incoming update
    }
  } finally {
    // Be sure to close the client
    await client.close();
  }
}