Fetch exchange rates for accounts that require conversion for net worth rollups (#1983)

* Sync required exchange rates for accounts

* Refactor into concern

app/models/account.rb

@@ -1,5 +1,5 @@
 class Account < ApplicationRecord
-  include Syncable, Monetizable, Issuable, Chartable, Enrichable, Linkable
+  include Syncable, Monetizable, Issuable, Chartable, Enrichable, Linkable, Convertible
 
   validates :name, :balance, :currency, presence: true
 

app/models/account/balance/syncer.rb

@@ -19,6 +19,8 @@ class Account::Balance::Syncer
       if strategy == :forward
         update_account_info
       end
+
+      account.sync_required_exchange_rates
     end
   end
 

app/models/account/convertible.rb

@@ -0,0 +1,28 @@
+module Account::Convertible
+  extend ActiveSupport::Concern
+
+  def sync_required_exchange_rates
+    unless requires_exchange_rates?
+      Rails.logger.info("No exchange rate sync needed for account #{id}")
+      return
+    end
+
+    rates = ExchangeRate.find_rates(
+      from: currency,
+      to: target_currency,
+      start_date: start_date,
+      cache: true # caches from provider to DB
+    )
+
+    Rails.logger.info("Synced #{rates.count} exchange rates for account #{id}")
+  end
+
+  private
+    def target_currency
+      family.currency
+    end
+
+    def requires_exchange_rates?
+      currency != target_currency
+    end
+end