Showing presenter pattern with simple ruby code

presenter_pattern.rb

revenues = {
  2018 => 100000,
  2019 => 10000,
  2020 => 1000,
  2021 => 5000
}

class Financials

  attr_reader :revenues, :country

  def initialize(country:,revenues:)
    @country = country
    @revenues = revenues
  end

  def revenue_growths
    growths = {}
    revenues.each_with_index do |(year, revenue), i|
      if i==0
        growths[year] = nil
      else
        growths[year] = (revenue - revenues[year-1])/revenues[year-1].to_f
      end
    end
    growths
  end
end

class FinancialsPresenter
  def initialize(financials)
    @financials = financials
  end

  def revenues
    @financials.revenues.map { |year, revenue|
      [year, "#{currency}#{@financials.revenues[year]/1000}K"]
    }.to_h
  end

  def revenue_growths
    @financials.revenue_growths.map { |year, growth|
        [year, (growth.nil? ? "N/A" : "#{growth * 100}%")]
      }.to_h
  end

  private
  def currency
    case @financials.country
    when "UK", "GB"
      "€"
    when "US"
      "$"
    end
  end
end

def show_report(revenues)
  f = Financials.new(country: "US", revenues: revenues)
  puts "year\trevenue\trevenue_growths"
  f.revenues.each do |year, revenue|
    puts "#{year}\t#{revenue}\t#{f.revenue_growths[year]}"
  end
end

def show_report2(revenues)
  f = Financials.new(country: "UK", revenues: revenues) 
  puts "year\trevenue\trevenue_growths"
  currency_symbol = case f.country
                    when "US" 
                      "$"
                    when "GB", "UK"
                      "€"
                    end
  f.revenues.each do |year, revenue|
    revenue_k = "#{revenue/1000}K"
    growth = if f.revenue_growths[year].nil?
               "N/A"
             else
               "#{f.revenue_growths[year] * 100}%"
             end
    puts "#{year}\t#{currency_symbol}#{revenue_k}\t#{growth}"
  end
end

def show_report3(revenues)
  f = FinancialsPresenter.new(Financials.new(country: "UK", revenues: revenues))

  puts "year\trevenue\trevenue_growths"
  f.revenues.each do |year, revenue|
    puts "#{year}\t#{revenue}\t#{f.revenue_growths[year]}"
  end
end


show_report(revenues)
show_report2(revenues)
show_report3(revenues)