Add income and spending insight cards to dashboard (#668)

* Generate time series for rolling 30 day sum of income and spending

* Highlight accounts with most income and spending in the last 30 days

* Aggregate chips after 3 top accounts in insight card

* Refactor aggregation filter

I think this is easier to read and understand whats happening at a
glance

* Refactor and tidy

* Use family currency for insight cards

* Further reduce risk of sql injection

* Fix lint

* Refactor rolling total queries

* Add test for transaction snapshot

app/models/family.rb

@@ -28,6 +28,49 @@ class Family < ApplicationRecord
     }
   end
 
+  def snapshot_account_transactions
+    period = Period.last_30_days
+
+    results = accounts.active.joins(:transactions)
+      .select(
+        "accounts.*",
+        "COALESCE(SUM(amount) FILTER (WHERE amount > 0), 0) AS spending",
+        "COALESCE(SUM(-amount) FILTER (WHERE amount < 0), 0) AS income"
+      )
+      .where("transactions.date >= ?", period.date_range.begin)
+      .where("transactions.date <= ?", period.date_range.end)
+      .group("id")
+      .to_a
+
+    {
+      top_spenders: results.sort_by(&:spending).select { |a| a.spending > 0 }.reverse,
+      top_earners: results.sort_by(&:income).select { |a| a.income > 0 }.reverse
+    }
+  end
+
+  def snapshot_transactions
+    rolling_totals = Transaction.daily_rolling_totals(transactions, period: Period.last_30_days, currency: self.currency)
+
+    spending = []
+    income = []
+    rolling_totals.each do |r|
+      spending << {
+        date: r.date,
+        value: Money.new(r.rolling_spend, self.currency)
+      }
+
+      income << {
+        date: r.date,
+        value: Money.new(r.rolling_income, self.currency)
+      }
+    end
+
+    {
+      income_series: TimeSeries.new(income, favorable_direction: "up"),
+      spending_series: TimeSeries.new(spending, favorable_direction: "down")
+    }
+  end
+
   def effective_start_date
     accounts.active.joins(:balances).minimum("account_balances.date") || Date.current
   end