Sync required exchange rates for accounts

app/models/account/balance/syncer.rb

@@ -19,10 +19,16 @@ class Account::Balance::Syncer
       if strategy == :forward
         update_account_info
       end
+
+      sync_exchange_rates
     end
   end
 
   private
+    def sync_exchange_rates
+      Account::ExchangeRateSync.new(account).sync_rates
+    end
+
     def sync_holdings
       @holdings = Account::Holding::Syncer.new(account, strategy: strategy).sync_holdings
     end

app/models/account/exchange_rate_sync.rb

@@ -0,0 +1,32 @@
+class Account::ExchangeRateSync
+  def initialize(account)
+    @account = account
+  end
+
+  def sync_rates
+    Rails.logger.tagged("Account::ExchangeRateSync") do
+      unless needs_rate_sync?
+        Rails.logger.info("No exchange rate sync needed for account #{@account.id}")
+        return
+      end
+
+      rates = ExchangeRate.find_rates(
+        from: @account.currency,
+        to: target_currency,
+        start_date: @account.start_date,
+        cache: true # caches from provider to DB
+      )
+
+      Rails.logger.info("Synced #{rates.count} exchange rates for account #{@account.id}")
+    end
+  end
+
+  private
+    def target_currency
+      @account.family.currency
+    end
+
+    def needs_rate_sync?
+      @account.currency != target_currency
+    end
+end

test/models/account/chartable_test.rb

@@ -35,4 +35,27 @@ class Account::ChartableTest < ActiveSupport::TestCase
     assert_equal 3000, series.values.find { |v| v.date == 20.days.ago.to_date }.trend.current.amount
     assert_equal 3500, series.values.last.trend.current.amount
   end
+
+  test "generates correct totals for multi currency families" do
+    family = families(:empty)
+    family.update!(currency: "USD")
+
+    usd_account = family.accounts.create!(name: "Asset", currency: "USD", balance: 5000, accountable: Depository.new)
+    eur_account = family.accounts.create!(name: "Asset", currency: "EUR", balance: 1000, accountable: Depository.new)
+
+    usd_account.balances.create!(date: 3.days.ago.to_date, balance: 5000, currency: "USD")
+    eur_account.balances.create!(date: 3.days.ago.to_date, balance: 1000, currency: "EUR")
+
+    # 1 EUR = 1.1 USD, so 1000 EUR = 1100 USD
+    ExchangeRate.create!(from_currency: "EUR", to_currency: "USD", date: 3.days.ago.to_date, rate: 1.1)
+    ExchangeRate.create!(from_currency: "EUR", to_currency: "USD", date: 2.days.ago.to_date, rate: 1.1)
+    ExchangeRate.create!(from_currency: "EUR", to_currency: "USD", date: 1.days.ago.to_date, rate: 1.1)
+    ExchangeRate.create!(from_currency: "EUR", to_currency: "USD", date: Date.current, rate: 1.1)
+
+    series = family.accounts.balance_series(currency: "USD", period: Period.last_7_days)
+
+    assert_equal 0, series.values.first.trend.current.amount
+    assert_equal 6100, series.values.find { |v| v.date == 3.days.ago.to_date }.trend.current.amount
+    assert_equal 6100, series.values.last.trend.current.amount
+  end
 end

test/models/account/exchange_rate_sync_test.rb

@@ -0,0 +1,59 @@
+require "test_helper"
+require "ostruct"
+
+class Account::ExchangeRateSyncTest < ActiveSupport::TestCase
+  include Account::EntriesTestHelper
+
+  setup do
+    @family = families(:empty)
+    @family.update!(currency: "USD")
+
+    # Foreign account (currency is not in the family's primary currency, so it will require exchange rates for net worth rollups)
+    @account = @family.accounts.create!(name: "Test Account", currency: "EUR", balance: 10000, accountable: Depository.new)
+
+    @provider = mock
+    ExchangeRate.stubs(:provider).returns(@provider)
+  end
+
+  test "syncs required exchange rates for an account" do
+    create_valuation(account: @account, date: 5.days.ago.to_date, amount: 9500, currency: "EUR")
+
+    # Since we had a valuation 5 days ago, this account starts 6 days ago and needs daily exchange rates looking forward
+    assert_equal 6.days.ago.to_date, @account.start_date
+
+    @provider.expects(:fetch_exchange_rates)
+             .with(
+                from: "EUR",
+                to: "USD",
+                start_date: 6.days.ago.to_date,
+                end_date: Date.current
+              ).returns(
+                OpenStruct.new(
+                  success?: true,
+                  rates: [
+                    OpenStruct.new(date: 6.days.ago.to_date, rate: 1.1),
+                    OpenStruct.new(date: 5.days.ago.to_date, rate: 1.2),
+                    OpenStruct.new(date: 4.days.ago.to_date, rate: 1.3),
+                    OpenStruct.new(date: 3.days.ago.to_date, rate: 1.4),
+                    OpenStruct.new(date: 2.days.ago.to_date, rate: 1.5),
+                    OpenStruct.new(date: 1.day.ago.to_date, rate: 1.6),
+                    OpenStruct.new(date: Date.current, rate: 1.7)
+                  ]
+                )
+              )
+
+    assert_difference "ExchangeRate.count", 7 do
+      Account::ExchangeRateSync.new(@account).sync_rates
+    end
+  end
+
+  test "does not sync rates for a domestic account" do
+    @account.update!(currency: "USD")
+
+    @provider.expects(:fetch_exchange_rates).never
+
+    assert_no_difference "ExchangeRate.count" do
+      Account::ExchangeRateSync.new(@account).sync_rates
+    end
+  end
+end