# Must install the `typhoeus` gem for this example.
require 'typhoeus'

# These dependencies work for Ruby 2.1.2. Earlier versions of
# Ruby may need different requires or gems
require 'json'
require 'openssl'
require 'base64'
require 'cgi'

# You get these from your ChartURL.com account
# These are real credentials that we use for a public test account.
CHARTURL_KEY = "dek-d7a46236eda961a6c3c18ffcc6b077ba87d27e9ae85f7842c6d427c265dd5f69d5131308d93332353d4a55a4b1160fcf516515a4a9f0aa50fbf2d7a2e7d0f1c5"
CHARTURL_PROJECT_TOKEN = "dt-RwYN"

class ChartURL
  
  # This helper will try to generate an encrypted URL. The upside is that it
  # does not require an HTTP request to ChartURL. The downside is that the URL
  # could end being too long. In that case, it falls back to the
  # `ChartURL.short_url_for` method
  def self.url_for template, options
    json = options.to_json
    cipher = OpenSSL::Cipher.new 'AES-256-CBC'
    cipher.encrypt
    iv = cipher.random_iv
    cipher.key =  OpenSSL::Digest::SHA256.new(CHARTURL_KEY).digest
    encrypted_json = cipher.update(json) + cipher.final

    iv_for_url = CGI.escape(Base64.encode64(iv))
    data_for_url = CGI.escape(Base64.encode64(encrypted_json))

    url = "https://charturl.com/i/#{CHARTURL_PROJECT_TOKEN}/#{template}/#{iv_for_url}/#{data_for_url}"

    if url.size > 1500
      short_url_for(template, options)
    else
      url
    end
  end

  def self.short_url_for template, options
    url = "https://charturl.com/short-urls.json?api_key=#{API_KEY}"
    headers = {'Content-Type' => 'application/json'}
    body = options.merge(template: template).to_json
    surl_response = Typhoeus::Request.post(url, body: body, headers: headers)
    raise("Error creating ShortURL: #{surl_response.inspect}") if !surl_response.success?
    JSON.parse(surl_response.body)['short_url']
  end
end


# Do whatever you need to create data
def data_for_chart
  {
    options: {
      data: {
        columns: [
          ['Last week'] + 7.times.map { rand(40) + 10 },
          ['This week'] + 7.times.map { rand(20) + 20 }
        ]
      }
    }
  }
end

# Generate the URL. The first parameter, `weekly-activity`, is the slug
# for a template you create over at ChartURL.com. This template contains
# your style and chart options like axes labels, typography, etc....
def charturl_url
  ChartURL.url_for('weekly-activity', data_for_chart)
end