feat: Telegram Channel (#2901)

- Ability to configure telegram bots as a channel in chatwoot
- Receive a message sent to the telegram bot in chatwoot
- Ability to reply to telegram users from chatwoot
- Receive attachment messages in chatwoot

fixes: #1843

app/services/telegram/incoming_message_service.rb

@@ -0,0 +1,106 @@
+class Telegram::IncomingMessageService
+  include ::FileTypeHelper
+  pattr_initialize [:inbox!, :params!]
+
+  def perform
+    set_contact
+    update_contact_avatar
+    set_conversation
+    @message = @conversation.messages.create(
+      content: params[:message][:text],
+      account_id: @inbox.account_id,
+      inbox_id: @inbox.id,
+      message_type: :incoming,
+      sender: @contact,
+      source_id: (params[:message][:message_id]).to_s
+    )
+    attach_files
+    @message.save!
+  end
+
+  private
+
+  def account
+    @account ||= inbox.account
+  end
+
+  def set_contact
+    contact_inbox = ::ContactBuilder.new(
+      source_id: params[:message][:from][:id],
+      inbox: inbox,
+      contact_attributes: contact_attributes
+    ).perform
+
+    @contact_inbox = contact_inbox
+    @contact = contact_inbox.contact
+  end
+
+  def update_contact_avatar
+    return if @contact.avatar.attached?
+
+    avatar_url = inbox.channel.get_telegram_profile_image(params[:message][:from][:id])
+    ::ContactAvatarJob.perform_later(@contact, avatar_url) if avatar_url
+  end
+
+  def conversation_params
+    {
+      account_id: @inbox.account_id,
+      inbox_id: @inbox.id,
+      contact_id: @contact.id,
+      contact_inbox_id: @contact_inbox.id,
+      additional_attributes: conversation_additional_attributes
+    }
+  end
+
+  def set_conversation
+    @conversation = @contact_inbox.conversations.first
+    return if @conversation
+
+    @conversation = ::Conversation.create!(conversation_params)
+  end
+
+  def contact_attributes
+    {
+      name: "#{params[:message][:from][:first_name]} #{params[:message][:from][:last_name]}",
+      additional_attributes: additional_attributes
+    }
+  end
+
+  def additional_attributes
+    {
+      username: params[:message][:from][:username],
+      language_code: params[:message][:from][:language_code]
+    }
+  end
+
+  def conversation_additional_attributes
+    {
+      chat_id: params[:message][:chat][:id]
+    }
+  end
+
+  def file_content_type
+    params[:message][:photo].present? ? :image : file_type(params[:message][:document][:mime_type])
+  end
+
+  def attach_files
+    file = params[:message][:document]
+    file ||= params[:message][:photo]&.last
+
+    return unless file
+
+    attachment_file = Down.download(
+      inbox.channel.get_telegram_file_path(file[:file_id])
+    )
+
+    @message.attachments.new(
+      account_id: @message.account_id,
+      file_type: file_content_type,
+      file: {
+        io: attachment_file,
+        filename: attachment_file.original_filename,
+        content_type: attachment_file.content_type
+      }
+    )
+  end
+end

app/services/telegram/send_on_telegram_service.rb

@@ -0,0 +1,22 @@
+class Telegram::SendOnTelegramService < Base::SendOnChannelService
+  private
+
+  def channel_class
+    Channel::Telegram
+  end
+
+  def perform_reply
+    ## send reply to telegram message api
+    # https://core.telegram.org/bots/api#sendmessage
+    message_id = channel.send_message_on_telegram(message.content, conversation[:additional_attributes]['chat_id'])
+    message.update!(source_id: message_id) if message_id.present?
+  end
+
+  def inbox
+    @inbox ||= message.inbox
+  end
+
+  def channel
+    @channel ||= inbox.channel
+  end
+end