Feature: Slack integration (#783)

- Integrations architecture
- Slack integration

lib/integrations/slack/channel_builder.rb

@@ -0,0 +1,33 @@
+class Integrations::Slack::ChannelBuilder
+  attr_reader :params, :channel
+
+  def initialize(params)
+    @params = params
+  end
+
+  def perform
+    create_channel
+    update_reference_id
+  end
+
+  private
+
+  def hook
+    @hook ||= params[:hook]
+  end
+
+  def slack_client
+    Slack.configure do |config|
+      config.token = hook.access_token
+    end
+    Slack::Web::Client.new
+  end
+
+  def create_channel
+    @channel = slack_client.conversations_create(name: params[:channel])
+  end
+
+  def update_reference_id
+    @hook.reference_id = channel['channel']['id']
+  end
+end

lib/integrations/slack/hook_builder.rb

@@ -0,0 +1,42 @@
+class Integrations::Slack::HookBuilder
+  attr_reader :params
+
+  def initialize(params)
+    @params = params
+  end
+
+  def perform
+    token = fetch_access_token
+
+    hook = account.hooks.new(
+      access_token: token,
+      status: 'enabled',
+      inbox_id: params[:inbox_id],
+      hook_type: hook_type,
+      app_id: 'cw_slack'
+    )
+
+    hook.save!
+    hook
+  end
+
+  private
+
+  def account
+    params[:account]
+  end
+
+  def hook_type
+    params[:inbox_id] ? 'inbox' : 'account'
+  end
+
+  def fetch_access_token
+    client = Slack::Web::Client.new
+
+    client.oauth_access(
+      client_id: ENV.fetch('SLACK_CLIENT_ID', 'TEST_CLIENT_ID'),
+      client_secret: ENV.fetch('SLACK_CLIENT_SECRET', 'TEST_CLIENT_SECRET'),
+      code: params[:code]
+    )['bot']['bot_access_token']
+  end
+end

lib/integrations/slack/incoming_message_builder.rb

@@ -0,0 +1,78 @@
+class Integrations::Slack::IncomingMessageBuilder
+  attr_reader :params
+
+  SUPPORTED_EVENT_TYPES = %w[event_callback url_verification].freeze
+  SUPPORTED_EVENTS = %w[message].freeze
+  SUPPORTED_MESSAGE_TYPES = %w[rich_text].freeze
+
+  def initialize(params)
+    @params = params
+  end
+
+  def perform
+    return unless valid_event?
+
+    if hook_verification?
+      verify_hook
+    elsif create_message?
+      create_message
+    end
+  end
+
+  private
+
+  def valid_event?
+    supported_event_type? && supported_event?
+  end
+
+  def supported_event_type?
+    SUPPORTED_EVENT_TYPES.include?(params[:type])
+  end
+
+  def supported_event?
+    hook_verification? || SUPPORTED_EVENTS.include?(params[:event][:type])
+  end
+
+  def supported_message?
+    SUPPORTED_MESSAGE_TYPES.include?(message[:type])
+  end
+
+  def hook_verification?
+    params[:type] == 'url_verification'
+  end
+
+  def create_message?
+    supported_message? && integration_hook
+  end
+
+  def message
+    params[:event][:blocks].first
+  end
+
+  def verify_hook
+    {
+      challenge: params[:challenge]
+    }
+  end
+
+  def integration_hook
+    @integration_hook ||= Integrations::Hook.where(reference_id: params[:event][:channel])
+  end
+
+  def conversation
+    @conversation ||= Conversation.where(identifier: params[:event][:thread_ts]).first
+  end
+
+  def create_message
+    return unless conversation
+
+    conversation.messages.create(
+      message_type: 0,
+      account_id: conversation.account_id,
+      inbox_id: conversation.inbox_id,
+      content: message[:elements].first[:elements].first[:text]
+    )
+
+    { status: 'success' }
+  end
+end

lib/integrations/slack/outgoing_message_builder.rb

@@ -0,0 +1,50 @@
+class Integrations::Slack::OutgoingMessageBuilder
+  attr_reader :hook, :message
+
+  def self.perform(hook, message)
+    new(hook, message).perform
+  end
+
+  def initialize(hook, message)
+    @hook = hook
+    @message = message
+  end
+
+  def perform
+    send_message
+    update_reference_id
+  end
+
+  private
+
+  def conversation
+    @conversation ||= message.conversation
+  end
+
+  def contact
+    @contact ||= conversation.contact
+  end
+
+  def send_message
+    @slack_message = slack_client.chat_postMessage(
+      channel: hook.reference_id,
+      text: message.content,
+      username: contact.try(:name),
+      thread_ts: conversation.identifier
+    )
+  end
+
+  def update_reference_id
+    return if conversation.identifier
+
+    conversation.identifier = @slack_message['ts']
+    conversation.save!
+  end
+
+  def slack_client
+    Slack.configure do |config|
+      config.token = hook.access_token
+    end
+    Slack::Web::Client.new
+  end
+end