require 'sinatra/base'
require 'faraday'
require 'json'

class CPIFeed < Sinatra::Base
  DEFAULT_CPI_SERIES_URL = 'http://api.bls.gov/publicAPI/v2/timeseries/data/CUUSA210SA0'

  get '/' do
    resp = JSON.parse(Faraday.get(cpi_series_url).body)

    expires 300, :public, :must_revalidate
    content_type :csv
    "cpi\n#{resp['Results']['series'].first['data'].first['value']}\n"
  end

  def cpi_series_url
    ENV['CPI_SERIES_URL'] || DEFAULT_CPI_SERIES_URL
  end

  run! if app_file == $PROGRAM_FILE
end