# A little toy file demonstrating how to build chainable
# data transformations that reveal some amount of intent
# through named extracted methods.
#
# Kudos to @mfeathers for giving me the idea to try this
#
# Copyright Test Double, LLC, 2016. All Rights Reserved.

require_relative "marketing_refinements"

class MarketResearch

  # Vanilla / Anonymous / Primitive approach to chaining

  def income_by_smoking(data)
    Hash[
      data.reject {|p| p[:income] < 10_000 }.
      group_by { |p| p[:smoker] }.
      map { |(is_smoker, people)|
        [
          is_smoker ? :smokers : :non_smokers,
          people.map {|p| p[:income]}.reduce(:+).to_f / people.size
        ]
      }
    ]
  end

  # Refined approach to tacking named domain abstractions onto Array/Hash

  using MarketingRefinements
  def income_by_smoking_fancy(data)
    data.exclude_incomes_under(10_000).
         separate_people_by(:smoker).
         average_income_by_smoking
  end
end

DATA = [
  {age: 19, smoker: false, income: 10_000, education: :high_school},
  {age: 49, smoker: true, income: 120_000, education: :bachelors},
  {age: 55, smoker: false, income: 400_000, education: :masters},
  {age: 23, smoker: true, income: 10_000, education: :bachelors},
  {age: 70, smoker: false, income: 70_000, education: :phd },
  {age: 34, smoker: false, income: 90_000, education: :masters},
  {age: 90, smoker: true, income: 0, education: :high_school},
]
original_result = MarketResearch.new.income_by_smoking(DATA)
fancy_result = MarketResearch.new.income_by_smoking_fancy(DATA)

puts <<-MSG
  Original result: #{original_result}
     Fancy result: #{fancy_result}
MSG