vat_rate/lib/vat_rate.rb

# frozen_string_literal: true

require_relative "vat_rate/version"

require 'psych'
require 'date'

class VatRate
  CATEGORIES = %i(standard parking reduced super_reduced)
  RATES = Psych.safe_load_file(__dir__ + "/vat_rate.yml", permitted_classes: [Date])

  def initialize(country:, category: :standard, date: Date.today, rate: nil)
    raise ArgumentError unless CATEGORIES.include?(category)

    @category = category
    @country = country.to_s
    @date = date

    if rate
      @rate = rate
    elsif RATES["#{@category}_rates"].key?(@country)
      @rate = RATES["#{@category}_rates"][@country].detect do |rate_data|
        if rate
          rate == rate_data['rate']
        else
          !rate_data.key?('from') || date.to_date >= rate_data['from']
        end
      end&.fetch('rate') || 0
    else
      @rate = 0
    end
  end

  attr_reader :rate

  def amount_with_vat(amount)
    amount * (100 + @rate) / 100.0
  end

  def amount_without_vat(amount)
    amount * 100.0 / (100 + @rate)
  end

  def vat_amount(amount, has_vat: false)
    if has_vat
      amount * @rate / (100.0 + @rate)
    else
      amount * @rate / 100.0
    end
  end
end