Start and end balance breakdown in activity view (#2466)

* Initial data objects

* Remove trend calculator

* Fill in balance reconciliation for entry group

* Initial tooltip component

* Balance trends in activity view

* Lint fixes

* trade partial alignment fix

* Tweaks to balance calculation to acknowledge holdings value better

* More lint fixes

* Bump brakeman dep

* Test fixes

* Remove unused class

app/models/account/activity_feed_data.rb

@@ -0,0 +1,219 @@
+# Data used to build the paginated feed of account "activity" (events like transfers, deposits, withdrawals, etc.)
+# This data object is useful for avoiding N+1 queries and having an easy way to pass around the required data to the
+# activity feed component in controllers and background jobs that refresh it.
+class Account::ActivityFeedData
+  ActivityDateData = Data.define(:date, :entries, :balance_trend, :cash_balance_trend, :holdings_value_trend, :transfers)
+
+  attr_reader :account, :entries
+
+  def initialize(account, entries)
+    @account = account
+    @entries = entries.to_a
+  end
+
+  def entries_by_date
+    @entries_by_date_objects ||= begin
+      grouped_entries.map do |date, date_entries|
+        ActivityDateData.new(
+          date: date,
+          entries: date_entries,
+          balance_trend: balance_trend_for_date(date),
+          cash_balance_trend: cash_balance_trend_for_date(date),
+          holdings_value_trend: holdings_value_trend_for_date(date),
+          transfers: transfers_for_date(date)
+        )
+      end
+    end
+  end
+
+  private
+    def balance_trend_for_date(date)
+      build_trend_for_date(date, :balance_money)
+    end
+
+    def cash_balance_trend_for_date(date)
+      date_entries = grouped_entries[date] || []
+      has_valuation = date_entries.any?(&:valuation?)
+
+      if has_valuation
+        # When there's a valuation, calculate cash change from transaction entries only
+        transactions = date_entries.select { |e| e.transaction? }
+        cash_change = sum_entries_with_exchange_rates(transactions, date) * -1
+
+        start_balance = start_balance_for_date(date)
+        Trend.new(
+          current: start_balance.cash_balance_money + cash_change,
+          previous: start_balance.cash_balance_money
+        )
+      else
+        build_trend_for_date(date, :cash_balance_money)
+      end
+    end
+
+    def holdings_value_trend_for_date(date)
+      date_entries = grouped_entries[date] || []
+      has_valuation = date_entries.any?(&:valuation?)
+
+      if has_valuation
+        # When there's a valuation, calculate holdings change from trade entries only
+        trades = date_entries.select { |e| e.trade? }
+        holdings_change = sum_entries_with_exchange_rates(trades, date)
+
+        start_balance = start_balance_for_date(date)
+        start_holdings = start_balance.balance_money - start_balance.cash_balance_money
+        Trend.new(
+          current: start_holdings + holdings_change,
+          previous: start_holdings
+        )
+      else
+        build_trend_for_date(date) do |balance|
+          balance.balance_money - balance.cash_balance_money
+        end
+      end
+    end
+
+    def transfers_for_date(date)
+      date_entries = grouped_entries[date] || []
+      return [] if date_entries.empty?
+
+      date_transaction_ids = date_entries.select(&:transaction?).map(&:entryable_id)
+      return [] if date_transaction_ids.empty?
+
+      # Convert to Set for O(1) lookups
+      date_transaction_id_set = Set.new(date_transaction_ids)
+
+      transfers.select { |txfr|
+        date_transaction_id_set.include?(txfr.inflow_transaction_id) ||
+        date_transaction_id_set.include?(txfr.outflow_transaction_id)
+      }
+    end
+
+    def build_trend_for_date(date, method = nil)
+      start_balance = start_balance_for_date(date)
+      end_balance = end_balance_for_date(date)
+
+      if block_given?
+        Trend.new(
+          current: yield(end_balance),
+          previous: yield(start_balance)
+        )
+      else
+        Trend.new(
+          current: end_balance.send(method),
+          previous: start_balance.send(method)
+        )
+      end
+    end
+
+    # Finds the balance on date, or the most recent balance before it ("last observation carried forward")
+    def start_balance_for_date(date)
+      @start_balance_for_date ||= {}
+      @start_balance_for_date[date] ||= last_observed_balance_before_date(date.prev_day) || generate_fallback_balance(date)
+    end
+
+    # Finds the balance on date, or the most recent balance before it ("last observation carried forward")
+    def end_balance_for_date(date)
+      @end_balance_for_date ||= {}
+      @end_balance_for_date[date] ||= last_observed_balance_before_date(date) || generate_fallback_balance(date)
+    end
+
+    RequiredExchangeRate = Data.define(:date, :from, :to)
+
+    def grouped_entries
+      @grouped_entries ||= entries.group_by(&:date)
+    end
+
+    def needs_exchange_rates?
+      entries.any? { |entry| entry.currency != account.currency }
+    end
+
+    def required_exchange_rates
+      multi_currency_entries = entries.select { |entry| entry.currency != account.currency }
+
+      multi_currency_entries.map do |entry|
+        RequiredExchangeRate.new(date: entry.date, from: entry.currency, to: account.currency)
+      end.uniq
+    end
+
+    # If the account has entries denominated in a different currency than the main account, we attach necessary
+    # exchange rates required to "roll up" the entry group balance into the normal account currency.
+    def exchange_rates
+      return [] unless needs_exchange_rates?
+
+      @exchange_rates ||= begin
+        rate_requirements = required_exchange_rates
+        return [] if rate_requirements.empty?
+
+        # Use ActiveRecord's or chain for better performance
+        conditions = rate_requirements.map do |req|
+          ExchangeRate.where(date: req.date, from_currency: req.from, to_currency: req.to)
+        end.reduce(:or)
+
+        conditions.to_a
+      end
+    end
+
+    def exchange_rate_for(date, from_currency, to_currency)
+      return 1.0 if from_currency == to_currency
+
+      rate = exchange_rates.find { |r| r.date == date && r.from_currency == from_currency && r.to_currency == to_currency }
+      rate&.rate || 1.0  # Fallback to 1:1 if no rate found
+    end
+
+    def sum_entries_with_exchange_rates(entries, date)
+      return Money.new(0, account.currency) if entries.empty?
+
+      entries.sum do |entry|
+        amount = entry.amount_money
+        if entry.currency != account.currency
+          rate = exchange_rate_for(date, entry.currency, account.currency)
+          Money.new(amount.amount * rate, account.currency)
+        else
+          amount
+        end
+      end
+    end
+
+    # We read balances so we can show "start of day" -> "end of day" balances for each entry date group in the feed
+    def balances
+      @balances ||= begin
+        return [] if entries.empty?
+
+        min_date = entries.min_by(&:date).date.prev_day
+        max_date = entries.max_by(&:date).date
+
+        account.balances.where(date: min_date..max_date, currency: account.currency).order(:date).to_a
+      end
+    end
+
+    def transaction_ids
+      entries.select { |entry| entry.transaction? }.map(&:entryable_id)
+    end
+
+    def transfers
+      return [] if entries.select { |e| e.transaction? && e.transaction.transfer? }.empty?
+      return [] if transaction_ids.empty?
+
+      @transfers ||= Transfer.where(inflow_transaction_id: transaction_ids).or(Transfer.where(outflow_transaction_id: transaction_ids)).to_a
+    end
+
+    # Use binary search since balances are sorted by date
+    def last_observed_balance_before_date(date)
+      idx = balances.bsearch_index { |b| b.date > date }
+
+      if idx
+        idx > 0 ? balances[idx - 1] : nil
+      else
+        balances.last
+      end
+    end
+
+    def generate_fallback_balance(date)
+      Balance.new(
+        account: account,
+        date: date,
+        balance: 0,
+        currency: account.currency
+      )
+    end
+end

app/models/account/reconcileable.rb

@@ -3,13 +3,13 @@ module Account::Reconcileable
 
   def create_reconciliation(balance:, date:, dry_run: false)
     result = reconciliation_manager.reconcile_balance(balance: balance, date: date, dry_run: dry_run)
-    sync_later if result.success?
+    sync_later if result.success? && !dry_run
     result
   end
 
   def update_reconciliation(existing_valuation_entry, balance:, date:, dry_run: false)
     result = reconciliation_manager.reconcile_balance(balance: balance, date: date, existing_valuation_entry: existing_valuation_entry, dry_run: dry_run)
-    sync_later if result.success?
+    sync_later if result.success? && !dry_run
     result
   end