Multi-currency support (#425)

* Initial foundational pass at multi-currency

* Default format currency

* More work on currency and exchanging

* Re-build currencies on change

* Currency import/setup

* Background job overhaul + cheaper OXR plan support

* Lint fixes

* Test fixes

* Multi-currency setup instructions

* Allow decimals in the balance field

* Spacing fix for form

---------

Signed-off-by: Josh Pigford <josh@joshpigford.com>

app/jobs/convert_currency_job.rb

@@ -0,0 +1,19 @@
+class ConvertCurrencyJob < ApplicationJob
+  queue_as :default
+
+  def perform(family)
+    family = Family.find(family.id)
+
+    # Convert all account balances to new currency
+    family.accounts.each do |account|
+      if account.original_currency == family.currency
+        account.converted_balance = account.original_balance
+        account.converted_currency = account.original_currency
+      else
+        account.converted_balance = ExchangeRate.convert(account.original_currency, family.currency, account.original_balance)
+        account.converted_currency = family.currency
+      end
+      account.save!
+    end
+  end
+end

app/jobs/daily_exchange_rate_job.rb

@@ -0,0 +1,34 @@
+class DailyExchangeRateJob < ApplicationJob
+  queue_as :default
+
+  def perform
+    app_id = ENV["OPEN_EXCHANGE_APP_ID"]
+
+    # Get the last date for which exchange rates were fetched for each currency
+    last_fetched_dates = ExchangeRate.group(:base_currency).maximum(:date)
+
+    # Loop through each currency and fetch exchange rates for each
+    Currency.all.each do |currency|
+      last_fetched_date = last_fetched_dates[currency.iso_code] || Date.yesterday
+      next_day = last_fetched_date + 1.day
+      response = Faraday.get("https://openexchangerates.org/api/historical/#{next_day}.json") do |req|
+        req.params["app_id"] = app_id
+        req.params["base"] = currency.iso_code
+        req.params["symbols"] = Currency.where.not(iso_code: currency.iso_code).pluck(:iso_code).join(",")
+      end
+
+      if response.success?
+        rates = JSON.parse(response.body)["rates"]
+
+        rates.each do |currency_iso_code, value|
+          ExchangeRate.find_or_create_by(date: Date.today, base_currency: currency.iso_code, converted_currency: currency_iso_code) do |exchange_rate|
+            exchange_rate.rate = value
+          end
+          puts "#{currency.iso_code} to #{currency_iso_code} on #{Date.today}: #{value}"
+        end
+      else
+        puts "Failed to fetch exchange rates for #{currency.iso_code} on #{Date.today}: #{response.status}"
+      end
+    end
+  end
+end