Add extra bills tracking

app/models/expense.rb

@@ -14,4 +14,12 @@ class Expense < ApplicationRecord
   def self.total
     Expense.sum(&:payment)
   end
+
+  def self.monthly_total
+    Expense.all.map(&:monthly).sum.round(2)
+  end
+
+  def self.autopaid_total
+    Expense.where(autopaid: true).map(&:monthly).sum.round(2)
+  end
 end

app/models/extra_bill.rb

@@ -0,0 +1,5 @@
+class ExtraBill < ApplicationRecord
+  def adjusted_amount
+    deduct_autopaid? ? amount - Expense.autopaid_total : amount
+  end
+end

app/models/member.rb

@@ -17,7 +17,7 @@ class Member < ApplicationRecord
     ((Income.total - others_included_income) / Income.total).round(2)
   end
 
-  def burden_amount
-    burden_percent * Expense.all.map(&:monthly).sum.round(2)
+  def burden_amount(total_amount: Expense.monthly_total)
+    burden_percent * total_amount
   end
 end