Feature: Twilio SMS Channel (#658)

Twilio SMS Channel
Fixes :  #350

app/controllers/api/v1/accounts/channels/twilio_channels_controller.rb

@@ -0,0 +1,50 @@
+class Api::V1::Accounts::Channels::TwilioChannelsController < Api::BaseController
+  before_action :authorize_request
+
+  def create
+    authenticate_twilio
+    build_inbox
+    setup_webhooks
+  rescue Twilio::REST::TwilioError => e
+    render_could_not_create_error(e.message)
+  rescue StandardError => e
+    render_could_not_create_error(e.message)
+  end
+
+  private
+
+  def authorize_request
+    authorize ::Inbox
+  end
+
+  def authenticate_twilio
+    client = Twilio::REST::Client.new(permitted_params[:account_sid], permitted_params[:auth_token])
+    client.messages.list(limit: 1)
+  end
+
+  def setup_webhooks
+    ::Twilio::WebhookSetupService.new(inbox: @inbox).perform
+  end
+
+  def build_inbox
+    ActiveRecord::Base.transaction do
+      twilio_sms = current_account.twilio_sms.create(
+        account_sid: permitted_params[:account_sid],
+        auth_token: permitted_params[:auth_token],
+        phone_number: permitted_params[:phone_number]
+      )
+      @inbox = current_account.inboxes.create(
+        name: permitted_params[:name],
+        channel: twilio_sms
+      )
+    rescue StandardError => e
+      render_could_not_create_error(e.message)
+    end
+  end
+
+  def permitted_params
+    params.require(:twilio_channel).permit(
+      :account_id, :phone_number, :account_sid, :auth_token, :name
+    )
+  end
+end