Improve chart performance and gapfilling (#2306)

app/models/account/chartable.rb

@@ -1,139 +1,26 @@
 module Account::Chartable
   extend ActiveSupport::Concern
 
-  class_methods do
-    def balance_series(currency:, period: Period.last_30_days, favorable_direction: "up", view: :balance, interval: nil)
-      raise ArgumentError, "Invalid view type" unless [ :balance, :cash_balance, :holdings_balance ].include?(view.to_sym)
-
-      series_interval = interval || period.interval
-
-      balances = Balance.find_by_sql([
-        balance_series_query,
-        {
-          start_date: period.start_date,
-          end_date: period.end_date,
-          interval: series_interval,
-          target_currency: currency
-        }
-      ])
-
-      balances = gapfill_balances(balances)
-      balances = invert_balances(balances) if favorable_direction == "down"
-
-      values = [ nil, *balances ].each_cons(2).map do |prev, curr|
-        Series::Value.new(
-          date: curr.date,
-          date_formatted: I18n.l(curr.date, format: :long),
-          trend: Trend.new(
-            current: Money.new(balance_value_for(curr, view), currency),
-            previous: prev.nil? ? nil : Money.new(balance_value_for(prev, view), currency),
-            favorable_direction: favorable_direction
-          )
-        )
-      end
-
-      Series.new(
-        start_date: period.start_date,
-        end_date: period.end_date,
-        interval: series_interval,
-        trend: Trend.new(
-          current: Money.new(balance_value_for(balances.last, view) || 0, currency),
-          previous: Money.new(balance_value_for(balances.first, view) || 0, currency),
-          favorable_direction: favorable_direction
-        ),
-        values: values
-      )
-    end
-
-    private
-      def balance_series_query
-        <<~SQL
-          WITH dates as (
-            SELECT generate_series(DATE :start_date, DATE :end_date, :interval::interval)::date as date
-            UNION DISTINCT
-            SELECT :end_date::date AS date -- Ensures we always end on user's "today" date, regardless of interval
-          )
-          SELECT
-            d.date,
-            SUM(CASE WHEN accounts.classification = 'asset' THEN ab.balance ELSE -ab.balance END * COALESCE(er.rate, 1)) as balance,
-            SUM(CASE WHEN accounts.classification = 'asset' THEN ab.cash_balance ELSE -ab.cash_balance END * COALESCE(er.rate, 1)) as cash_balance,
-            SUM(CASE WHEN accounts.classification = 'asset' THEN ab.balance - ab.cash_balance ELSE 0 END * COALESCE(er.rate, 1)) as holdings_balance,
-            COUNT(CASE WHEN accounts.currency <> :target_currency AND er.rate IS NULL THEN 1 END) as missing_rates
-          FROM dates d
-          LEFT JOIN accounts ON accounts.id IN (#{all.select(:id).to_sql})
-          LEFT JOIN balances ab ON (
-            ab.date = d.date AND
-            ab.currency = accounts.currency AND
-            ab.account_id = accounts.id
-          )
-          LEFT JOIN exchange_rates er ON (
-            er.date = ab.date AND
-            er.from_currency = accounts.currency AND
-            er.to_currency = :target_currency
-          )
-          GROUP BY d.date
-          ORDER BY d.date
-        SQL
-      end
-
-      def balance_value_for(balance_record, view)
-        return 0 if balance_record.nil?
-
-        case view.to_sym
-        when :balance then balance_record.balance
-        when :cash_balance then balance_record.cash_balance
-        when :holdings_balance then balance_record.holdings_balance
-        else
-          raise ArgumentError, "Invalid view type: #{view}"
-        end
-      end
-
-      def invert_balances(balances)
-        balances.map do |balance|
-          balance.balance = -balance.balance
-          balance.cash_balance = -balance.cash_balance
-          balance.holdings_balance = -balance.holdings_balance
-          balance
-        end
-      end
-
-      def gapfill_balances(balances)
-        gapfilled = []
-        prev = nil
-
-        balances.each do |curr|
-          if prev.nil?
-            # Initialize first record with zeros if nil
-            curr.balance ||= 0
-            curr.cash_balance ||= 0
-            curr.holdings_balance ||= 0
-          else
-            # Copy previous values for nil fields
-            curr.balance ||= prev.balance
-            curr.cash_balance ||= prev.cash_balance
-            curr.holdings_balance ||= prev.holdings_balance
-          end
-
-          gapfilled << curr
-          prev = curr
-        end
-
-        gapfilled
-      end
-  end
-
   def favorable_direction
     classification == "asset" ? "up" : "down"
   end
 
   def balance_series(period: Period.last_30_days, view: :balance, interval: nil)
-    self.class.where(id: self.id).balance_series(
-      currency: currency,
+    raise ArgumentError, "Invalid view type" unless [ :balance, :cash_balance, :holdings_balance ].include?(view.to_sym)
+
+    @balance_series ||= {}
+
+    memo_key = [ period.start_date, period.end_date, interval ].compact.join("_")
+
+    builder = (@balance_series[memo_key] ||= Balance::ChartSeriesBuilder.new(
+      account_ids: [ id ],
+      currency: self.currency,
       period: period,
-      view: view,
-      interval: interval,
-      favorable_direction: favorable_direction
-    )
+      favorable_direction: favorable_direction,
+      interval: interval
+    ))
+
+    builder.send("#{view}_series")
   end
 
   def sparkline_series