dblock/slack-market

module Api
  module Endpoints
    class SlackEndpoint < Grape::API
      format :json

      namespace :slack do
        desc 'Respond to interactive slack buttons and actions.'

        params do
          requires :payload, type: String
        end

        post '/action' do
          payload = JSON.parse(params[:payload])
          button_name = payload['actions'][0]['name']
          button_value = payload['actions'][0]['value']
          stock_symbol = button_value.scan(/^[^\-]*/)
          channel = payload['channel']['id']
          token = payload['token']
          ts = payload['original_message']['ts']
          chart = true

          error! 'Message token is not coming from Slack.',
                 401 if ENV.key?('SLACK_VERIFICATION_TOKEN') && token != ENV['SLACK_VERIFICATION_TOKEN']

          quotes = Market.quotes(Array(stock_symbol))
          slack_attachment = Market.to_slack_attachment(quotes.first, charts: chart, button: button_name)

          # formatted Slack message response
          {
            as_user: true,
            channel: channel,
            ts: ts,
            token: token,
            text: "Below is the #{button_name} chart",
            attachments: [slack_attachment]
          }
        end
      end
    end
  end
end