# Telegram::Bot

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Tools for developing bot for Telegram. Best used with Rails, but can be be used in
[standalone app](https://github.com/telegram-bot-rb/telegram-bot/wiki/Non-rails-application).
Supposed to be used in webhook-mode in production, and poller-mode
in development, but you can use poller in production if you want.

Package contains:

- Ligthweight client for bot API (with fast and thread-safe
  [httpclient](https://github.com/nahi/httpclient) under the hood).
- Controller with message parser. Allows to write separate methods for each command.
- Middleware and routes helpers for production env.
- Poller with automatic source-reloader for development env.
- Rake tasks to update webhook urls.
- __[Async mode](#async-mode)__ for Telegram and/or Botan API.
  Let the queue adapter handle network errors!

Here is sample [telegram_bot_app](https://github.com/telegram-bot-rb/telegram_bot_app)
with session, keyboards and inline queries.
Run it on your local machine in 1 minute!

And here is [app template](https://github.com/telegram-bot-rb/rails_template)
to generate clean app in seconds.

Examples and cookbook in [wiki](https://github.com/telegram-bot-rb/telegram-bot/wiki).

## Installation

Add this line to your application's Gemfile:

```ruby
gem 'telegram-bot'
```

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install telegram-bot

Require if necessary:

```ruby
require 'telegram/bot'
```

## Usage

### Configuration

Add `telegram` section into `secrets.yml`:

```yml
telegram:
  bots:
    # just set the token
    chat: TOKEN_1
    # or add username to support commands with mentions (/help@ChatBot)
    auction:
      token: TOKEN_2
      username: ChatBot

  # Single bot can be specified like this
  bot: TOKEN
  # or
  bot:
    token: TOKEN
    username: SomeBot
```

### Client

From now clients will be accessible with `Telegram.bots[:chat]` or `Telegram.bots[:auction]`.
Single bot can be accessed with `Telegram.bot` or `Telegram.bots[:default]`.

You can create clients manually with `Telegram::Bot::Client.new(token, username)`.
Username is optional and used only to parse commands with mentions.

There is `request(path_suffix, body)` method to perform any query.
And there are also shortcuts for available queries in underscored style
(`answer_inline_query` instead of `answerInlineQuery`).
All this methods just post given params to specific URL.

```ruby
bot.request(:getMe) or bot.get_me
bot.request(:getupdates, offset: 1) or bot.get_updates(offset: 1)
bot.send_message chat_id: chat_id, text: 'Test'
```

By default client will return parsed json responses. You can enable
response typecasting to virtus models using `telegram-bot-types` gem:
```ruby
# Add to your gemfile:
gem 'telegram-bot-types', '~> x.x.x'
# Enable typecasting:
Telegram::Bot::Client.typed_response!
# or for single instance:
bot.extend Telegram::Bot::Client::TypedResponse

bot.get_me.class # => Telegram::Bot::Types::User
```

Any API request error will raise `Telegram::Bot::Error` with description in its message.
Special `Telegram::Bot::Forbidden` is raised when bot can't post messages to the chat anymore.

### Controller

```ruby
class Telegram::WebhookController < Telegram::Bot::UpdatesController
  # use callbacks like in any other controllers
  around_action :with_locale

  # Every update can have one of: message, inline_query, chosen_inline_result,
  # callback_query.
  # Define method with same name to respond to this updates.
  def message(message)
    # message can be also accessed via instance method
    message == self.payload # true
    # store_message(message['text'])
  end

  # This basic methods receives commonly used params:
  #
  #   message(payload)
  #   inline_query(query, offset)
  #   chosen_inline_result(result_id, query)
  #   callback_query(data)

  # Define public methods to respond to commands.
  # Command arguments will be parsed and passed to the method.
  # Be sure to use splat args and default values to not get errors when
  # someone passed more or less arguments in the message.
  #
  # For some commands like /message or /123 method names should start with
  # `on_` to avoid conflicts.
  def start(data = nil, *)
    # do_smth_with(data)

    # There are `chat` & `from` shortcut methods.
    # For callback queries `chat` if taken from `message` when it's available.
    response = from ? "Hello #{from['username']}!" : 'Hi there!'
    # There is `respond_with` helper to set `chat_id` from received message:
    respond_with :message, text: response
    # `reply_with` also sets `reply_to_message_id`:
    reply_with :photo, photo: File.open('party.jpg')
  end

  private

  def with_locale(&block)
    I18n.with_locale(locale_for_update, &block)
  end

  def locale_for_update
    if from
      # locale for user
    elsif chat
      # locale for chat
    end
  end
end
```

#### Reply helpers

There are helpers to respond for basic actions. They just set chat/message/query
identifiers from update. See `ReplyHelpers` method for more information.
Here are this methods signatures:

```ruby
def respond_with(type, params); end
def reply_with(type, params); end
def answer_inline_query(results, params = {}); end
def answer_callback_query(text, params = {}); end
def edit_message(type, params = {}); end
```

#### Optional typecasting

You can enable typecasting of `update` with `telegram-bot-types` by including
`Telegram::Bot::UpdatesPoller::TypedUpdate`:

```ruby
class Telegram::WebhookController < Telegram::Bot::UpdatesController
  include Telegram::Bot::UpdatesController::TypedUpdate

  def message(message)
    message.class # => Telegram::Bot::Types::Message
  end
end
```

#### Session

This API is very close to ActiveController's session API, but works different
under the hood. Cookies can not be used to store session id or
whole session (like CookieStore does). So it uses key-value store and `session_key`
method to build identifier from update.

Store can be one of numerous `ActiveSupport::Cache` stores.
While `:file_store` is suitable for development and single-server deployments
without heavy load, it doesn't scale well. Key-value databases with persistance
like Redis are more appropriate for production use.

```ruby
# In rails app store can be configured in env files:
config.telegram_updates_controller.session_store = :redis_store, {expires_in: 1.month}

# In other app it can be done for all controllers with:
Telegram::Bot::UpdatesController.session_store = :redis_store, {expires_in: 1.month}
# or for specific one:
OneOfUpdatesController.session_store = :redis_store, {expires_in: 1.month}
```

Default session id is made from bot's username and `(from || chat)['id']`.
It means that session will be the same for updates from user in every chat,
and different for every user in the same group chat.
To change this behavior you can override `session_key` method, or even
define multiple sessions in single controller. For details see `Session` module.

```ruby
class Telegram::WebhookController < Telegram::Bot::UpdatesController
  include Telegram::Bot::UpdatesController::Session
  # or just shortcut:
  use_session!

  # You can override global config
  self.session_store = :file_store

  def write(text = nil, *)
    session[:text] = text
  end

  def read
    respond_with :message, text: session[:text]
  end

  private

  # In this case session will persist for user only in specific chat.
  # Same user in other chat will have different session.
  def session_key
    "#{bot.username}:#{chat['id']}:#{from['id']}" if chat && from
  end

  # This session will be the same for all updates in chat.
  def chat_session
    @_chat_session ||= self.class.build_session(chat && "#{bot.username}:#{chat['id']}")
  end
end
```

#### Message context

It's usual to support chain of messages like BotFather: after receiving command
it asks you for additional argument. There is `MessageContext` for this:

```ruby
class Telegram::WebhookController < Telegram::Bot::UpdatesController
  include Telegram::Bot::UpdatesController::MessageContext

  def rename(*)
    # set context for the next message
    save_context :rename
    respond_with :message, text: 'What name do you like?'
  end

  # register context handlers to handle this context
  context_handler :rename do |*words|
    update_name words[0]
    respond_with :message, text: 'Renamed!'
  end

  # You can do it in other way:
  def rename(name = nil, *)
    if name
      update_name name
      respond_with :message, text: 'Renamed!'
    else
      save_context :rename
      respond_with :message, text: 'What name do you like?'
    end
  end

  # This will call #rename like if it is called with message '/rename %text%'
  context_handler :rename

  # If you have a lot of such methods you can use
  context_to_action!
  # It'll use context value as action name for all contexts which miss handlers.
end
```

You can use `CallbackQueryContext` in the similar way to split `#callback_query` into
several specific methods. It doesn't require session support, and takes context from
data. If data has a prefix with colon like this `my_ctx:smth...` it'll call
`my_ctx_callback_query('smth...')` when there is such action method. Otherwise
it'll call `callback_query('my_ctx:smth...')` as usual.

#### Processesing updates

To process update run:

```ruby
ControllerClass.dispatch(bot, update)
```

There is also ability to run action without update:

```ruby
# Most likely you'll want to pass :from and :chat
controller = ControllerClass.new(bot, from: telegram_user, chat: telegram_chat)
controller.process(:help, *args)
```

### Routes

Use `telegram_webhooks` helper to add routes. It will create routes for bots
at "telegram/#{bot.token}" path.

```ruby
# Create routes for all Telegram.bots to use same controller:
telegram_webhooks TelegramController

# Or pass custom bots usin any of supported config options:
telegram_webhooks TelegramController,
                 bot,
                 {token: token, username: username},
                 other_bot_token

# Use different controllers for each bot:
telegram_webhooks bot => TelegramChatController,
                  other_bot => TelegramAuctionController

# telegram_webhooks creates named routes.
# Route name depends on `Telegram.bots`.
# When there is single bot it will use 'telegram_webhook'.
# When there are it will use bot's key in the `Telegram.bots` as prefix
# (eg. `chat_telegram_webhook`).
# You can override this options or specify others:
telegram_webhooks TelegramController, as: :my_webhook
telegram_webhooks bot => [TelegramChatController, as: :chat_webhook],
                  other_bot => TelegramAuctionController,
                  admin_chat: TelegramAdminChatController
```

For Rack applications you can also use `Telegram::Bot::Middleware` or just
call `.dispatch(bot, update)` on controller.

### Development & Debugging

Use `rake telegram:bot:poller` to run poller. It'll automatically load
changes without restart in development env. Optionally specify bot to run poller for
with `BOT` envvar (`BOT=chat`).

This task will not work if you don't use `telegram_webhooks`.
You can run poller manually with
`Telegram::Bot::UpdatesPoller.start(bot, controller_class)`.

### Testing

There is `Telegram::Bot::ClientStub` class to stub client for tests.
Instead of performing API requests it stores them in `requests` hash.

To stub all possible clients use `Telegram::Bot::ClientStub.stub_all!` before
initializing clients. Most likely you'll want something like this:

```ruby
# environments/test.rb
# Make sure to run it before defining routes or storing bot to some place in app!
Telegram.reset_bots
Telegram::Bot::ClientStub.stub_all!

# rails_helper.rb
RSpec.configure do |config|
  # ...
  config.after { Telegram.bot.reset }
  # or for multiple bots:
  config.after { Telegram.bots.each_value(&:reset) }
  # ...
end
```

There are integration and controller contexts for RSpec and some built-in matchers:

```ruby
# spec/requests/telegram_webhooks_spec.rb
require 'telegram/bot/rspec/integration'

RSpec.describe TelegramWebhooksController, :telegram_bot do
  # for old rspec add:
  # include_context 'telegram/bot/integration'

  describe '#start' do
    subject { -> { dispatch_command :start } }
    it { should respond_with_message 'Hi there!' }
  end

  # There is context for callback queries with related matchers.
  describe '#hey_callback_query', :callback_query do
    let(:data) { "hey:#{name}" }
    let(:name) { 'Joe' }
    it { should answer_callback_query('Hey Joe') }
    it { should edit_current_message :text, text: 'Done' }
end

# For controller specs use
require 'telegram/bot/updates_controller/rspec_helpers'
RSpec.describe TelegramWebhooksController, type: :telegram_bot_controller do
  # for old rspec add:
  # include_context 'telegram/bot/updates_controller'
end

# Matchers are available for custom specs:
include Telegram::Bot::RSpec::ClientMatchers

expect(&process_update).to send_telegram_message(bot, /msg regexp/, some: :option)
expect(&process_update).
  to make_telegram_request(bot, :sendMessage, hash_including(text: 'msg text'))
```

Place integration tests inside `spec/requests`
when using RSpec's `infer_spec_type_from_file_location!`,
or just add `type: :request` to `describe`.

See sample app for more examples.

### Deploying

Use `rake telegram:bot:set_webhook` to update webhook url for all configured bots.
Certificate can be specified with `CERT=path/to/cert`.

### Botan.io metrics

Initialize with `bot = Telegram::Bot::Client.new(token, botan: 'botan token')`
or just add `botan` key in `secrets.yml`:

```yml
  telegram:
    bot:
      token: bot_token
      botan: botan_token
```

Access to Botan client with `bot.botan`.
Use `bot.botan.track(event, uid, payload)` to track events.

There are some helpers for controllers in `Telegram::Bot::Botan::ControllerHelpers`:

```ruby
class Telegram::WebhookController < Telegram::Bot::UpdatesController
  include Telegram::Bot::Botan::ControllerHelpers

  # This will track with event: action_name & data: payload
  before_action :botan_track_action

  def smth(*)
    # This will track event for current user only when botan is configured.
    botan_track :my_event, custom_data

    # or get access directly to botan client:
    botan.track(...)
  end
end
```

There is no stubbing for botan clients, so don't set botan token in tests.

### Async mode

There is built in support for async requests using ActiveJob. Without Rails
you can implement your own worker class to handle such requests. This allows:

- Process updates very fast, without waiting for telegram and botan responses.
- Handle and retry network and other errors with queue adapter.
- ???

Instead of performing request instantly client serializes it, pushes to queue,
and immediately return control back. The job is then fetched with a worker
and real API request is performed. And this all is absolutely transparent for the app.

To enable this mode add `async: true` to bot's and botan's config.
For more information and custom configuration check out
[docs](http://www.rubydoc.info/github/telegram-bot-rb/telegram-bot/master/Telegram/Bot/Async) or
[source](https://github.com/telegram-bot-rb/telegram-bot/blob/master/lib/telegram/bot/async.rb).

If you want async mode, but don't want to setup queue, know that Rails 5 are shipped
with Async adapter by default, and there is
[Sucker Punch](https://github.com/brandonhilkert/sucker_punch) for Rails 4.

Be aware of some limitations:

- Client will not return API response.
- Sending files is not available in async mode [now],
  because them can not be serialized.

To disable async mode for the block of code use `bot.async(false) { bot.send_photo }`.
Yes, it's threadsafe too.

## Development

After checking out the repo, run `bin/setup` to install dependencies.
Then, run `rake spec` to run the tests.
You can also run `bin/console` for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run `bundle exec rake install`.
To release a new version, update the version number in `version.rb`,
and then run `bundle exec rake release`, which will create a git tag for the version,
push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).

### Different Rails versions

To setup development for specific major Rails version use:

```
RAILS=5 bundle install
# or
RAILS=5 bundle update
```

## Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/telegram-bot-rb/telegram-bot.