dawarich/app/services/yearly_digests/first_time_visits_calculator.rb

# frozen_string_literal: true

module YearlyDigests
  class FirstTimeVisitsCalculator
    def initialize(user, year)
      @user = user
      @year = year.to_i
    end

    def call
      {
        'countries' => first_time_countries,
        'cities' => first_time_cities
      }
    end

    private

    attr_reader :user, :year

    def previous_years_stats
      @previous_years_stats ||= user.stats.where('year < ?', year)
    end

    def current_year_stats
      @current_year_stats ||= user.stats.where(year: year)
    end

    def previous_countries
      @previous_countries ||= extract_countries(previous_years_stats)
    end

    def previous_cities
      @previous_cities ||= extract_cities(previous_years_stats)
    end

    def current_countries
      @current_countries ||= extract_countries(current_year_stats)
    end

    def current_cities
      @current_cities ||= extract_cities(current_year_stats)
    end

    def first_time_countries
      (current_countries - previous_countries).sort
    end

    def first_time_cities
      (current_cities - previous_cities).sort
    end

    def extract_countries(stats)
      stats.flat_map do |stat|
        toponyms = stat.toponyms
        next [] unless toponyms.is_a?(Array)

        toponyms.filter_map { |t| t['country'] if t.is_a?(Hash) }
      end.uniq.compact
    end

    def extract_cities(stats)
      stats.flat_map do |stat|
        toponyms = stat.toponyms
        next [] unless toponyms.is_a?(Array)

        toponyms.flat_map do |t|
          next [] unless t.is_a?(Hash) && t['cities'].is_a?(Array)

          t['cities'].filter_map { |c| c['city'] if c.is_a?(Hash) }
        end
      end.uniq.compact
    end
  end
end