require 'split'
require 'csv'
require 'bigdecimal'

if CSV.const_defined? :Reader
  require 'fastercsv'
  CSV = FasterCSV
end

module Split
  module Export
    extend self
    
    def round(number, precision = 2)
      BigDecimal.new(number.to_s).round(precision).to_f
    end

    def to_csv
      csv = CSV.generate do |csv|
        csv << ['Experiment', 'Alternative', 'Participants', 'Completed', 'Conversion Rate', 'Z score', 'Control', 'Winner']
        Split::Experiment.all.each do |experiment|
          experiment.alternatives.each do |alternative|
            csv << [experiment.name,
                    alternative.name,
                    alternative.participant_count,
                    alternative.completed_count,
                    round(alternative.conversion_rate, 3),
                    round(alternative.z_score, 3),
                    alternative.control?,
                    alternative.to_s == experiment.winner.to_s]
          end
        end
      end
    end
  end
end