Get a daily countdown to Vaccine Day UK

vaccine_countdown.rb

require 'active_support/all'
require 'HTTParty'
require 'json'

UK_CHILD_DECIMAL = 0.189
UK_ADULT_DECIMAL = 1.0 - UK_CHILD_DECIMAL
UK_POPULATION = 67_886_004.0
UK_ADULT_POPULATION = UK_POPULATION * UK_ADULT_DECIMAL
DOWNLOAD_URL = 'https://api.coronavirus.data.gov.uk/v1/data?filters=areaType=nation&structure={"date":"date","total":"cumPeopleVaccinatedFirstDoseByPublishDate","new":"newPeopleVaccinatedFirstDoseByPublishDate"}'
# v2 is not working today (Jan. 26), and instead respondes with a
# "412 Precondition Failed" ...
# "https://api.coronavirus.data.gov.uk/v2/data?areaType=overview&metric=cumPeopleVaccinatedFirstDoseByPublishDate&metric=newPeopleVaccinatedFirstDoseByPublishDate&format=json"
# ^ from https://coronavirus.data.gov.uk/details/download

# TOTALDELTA = (6853327-5962544)
# TOTALDELTA = (7164387-6221850)
# TOTALDELTA = (7447199-6473752)
# TOTALDELTA = (7891184-6816945)
# FUN: API v1 doesn't appear to have correct info for
# cumPeopleVaccinatedFirstDoseByPublishDate
# We get a number, but it is always underreported.
# This delta as an integer does not hold every day.
# (Thus far it is growing, but I have few data points as of yet.)
# So, I've averaged the percent they are underreported
# which is AVERAGE_MISS
AVERAGE_MISS = 0.1522091537079264

class VaccineDay
  class << self
    def predict
      data        = get_data
      parsed_data = parse(data)
      throughput  = calculate_throughput(parsed_data)
      dates       = calulate_dates(throughput)

      report(dates, throughput)
    end

    def get_data
      HTTParty.get(DOWNLOAD_URL)
    end

    def parse(raw)
      puts raw.code
      puts raw.body[0..100]
      JSON.parse(raw.body, symbolize_names: true)[:data]
    end

    def calculate_throughput(results)
      upto_date = results.first[:date]
      vaccinated = results.first[:total] * (1+AVERAGE_MISS)

      last_seven_daily = results[0..6].map do |result|
        result[:new]
      end

      {
        vaccinated: vaccinated,
        upto_date: upto_date,
        last_seven_average: ((last_seven_daily.inject(:+))/7.0),
        percent_vaccinated: (vaccinated/UK_ADULT_POPULATION)
      }
    end

    def calulate_dates(throughput)
      days_to_fifty = days_to(0.5, throughput)
      days_to_total = days_to(1.0, throughput)
      {
        days_to_fifty: days_to_fifty,
        days_to_total: days_to_total,
        fifty_day: (Date.today + days_to_fifty),
        total_day: (Date.today + days_to_total)
      }
    end

    def days_to(percentage, throughput)
      (((percentage - throughput[:percent_vaccinated]) * UK_ADULT_POPULATION)/throughput[:last_seven_average])
    end

    def report(dates, throughput)
      puts "* #{(throughput[:percent_vaccinated] * 100.0).round(2)}% of UK adults (#{throughput[:vaccinated].to_i.to_s(:delimited)}) have received their first vaccine dose as of #{throughput[:upto_date].to_s}"; sleep(0.2)
      puts "* #{dates[:days_to_fifty].round(0)} days (#{dates[:fifty_day].to_s}) before 50% of UK adults receive first vaccine dose"; sleep(0.2)
      puts "* #{dates[:days_to_total].round(0)} days (#{dates[:total_day].to_s}) before all UK adults receive single day vaccine"; sleep(0.2)
      puts "(throughput based on a rolling 7 day average)"; sleep(0.05)
    end
  end
end

VaccineDay.predict