loan: Set the first valuation as the original principal. (#2088)

Fix: #1645.

app/controllers/loans_controller.rb

@@ -2,6 +2,6 @@ class LoansController < ApplicationController
   include AccountableResource
 
   permitted_accountable_attributes(
-    :id, :rate_type, :interest_rate, :term_months
+    :id, :rate_type, :interest_rate, :term_months, :initial_balance
   )
 end

app/models/account.rb

@@ -34,6 +34,7 @@ class Account < ApplicationRecord
     def create_and_sync(attributes)
       attributes[:accountable_attributes] ||= {} # Ensure accountable is created, even if empty
       account = new(attributes.merge(cash_balance: attributes[:balance]))
+      initial_balance = attributes.dig(:accountable_attributes, :initial_balance)&.to_d || 0
 
       transaction do
         # Create 2 valuations for new accounts to establish a value history for users to see
@@ -47,7 +48,7 @@ class Account < ApplicationRecord
         account.entries.build(
           name: "Initial Balance",
           date: 1.day.ago.to_date,
-          amount: 0,
+          amount: initial_balance,
           currency: account.currency,
           entryable: Account::Valuation.new
         )
@@ -92,11 +93,6 @@ class Account < ApplicationRecord
     end
   end
 
-  def original_balance
-    balance_amount = balances.chronological.first&.balance || balance
-    Money.new(balance_amount, currency)
-  end
-
   def current_holdings
     holdings.where(currency: currency, date: holdings.maximum(:date)).order(amount: :desc)
   end
@@ -104,9 +100,13 @@ class Account < ApplicationRecord
   def update_with_sync!(attributes)
     should_update_balance = attributes[:balance] && attributes[:balance].to_d != balance
 
+    initial_balance = attributes.dig(:accountable_attributes, :initial_balance)
+    should_update_initial_balance = initial_balance && initial_balance.to_d != accountable.initial_balance
+
     transaction do
       update!(attributes)
       update_balance!(attributes[:balance]) if should_update_balance
+      update_inital_balance!(attributes[:accountable_attributes][:initial_balance]) if should_update_initial_balance
     end
 
     sync_later
@@ -127,11 +127,34 @@ class Account < ApplicationRecord
     end
   end
 
+  def update_inital_balance!(initial_balance)
+    valuation = first_valuation
+
+    if valuation
+      valuation.update! amount: initial_balance
+    else
+      entries.create! \
+        date: Date.current,
+        name: "Initial Balance",
+        amount: initial_balance,
+        currency: currency,
+        entryable: Account::Valuation.new
+    end
+  end
+
   def start_date
     first_entry_date = entries.minimum(:date) || Date.current
     first_entry_date - 1.day
   end
 
+  def first_valuation
+    entries.account_valuations.order(:date).first
+  end
+
+  def first_valuation_amount
+    first_valuation&.amount_money || balance_money
+  end
+
   private
     def sync_balances
       strategy = linked? ? :reverse : :forward

app/models/loan.rb

@@ -3,20 +3,24 @@ class Loan < ApplicationRecord
 
   def monthly_payment
     return nil if term_months.nil? || interest_rate.nil? || rate_type.nil? || rate_type != "fixed"
-    return Money.new(0, account.currency) if account.original_balance.amount.zero? || term_months.zero?
+    return Money.new(0, account.currency) if account.loan.original_balance.amount.zero? || term_months.zero?
 
     annual_rate = interest_rate / 100.0
     monthly_rate = annual_rate / 12.0
 
     if monthly_rate.zero?
-      payment = account.original_balance.amount / term_months
+      payment = account.loan.original_balance.amount / term_months
     else
-      payment = (account.original_balance.amount * monthly_rate * (1 + monthly_rate)**term_months) / ((1 + monthly_rate)**term_months - 1)
+      payment = (account.loan.original_balance.amount * monthly_rate * (1 + monthly_rate)**term_months) / ((1 + monthly_rate)**term_months - 1)
     end
 
     Money.new(payment.round, account.currency)
   end
 
+  def original_balance
+    Money.new(account.first_valuation_amount, account.currency)
+  end
+
   class << self
     def color
       "#D444F1"

app/views/loans/_form.html.erb

@@ -5,6 +5,13 @@
 
   <div class="space-y-2">
     <%= form.fields_for :accountable do |loan_form| %>
+      <div class="flex items-center gap-2">
+        <%= loan_form.money_field :initial_balance,
+                                 label: t("loans.form.initial_balance"),
+                                 default_currency: Current.family.currency,
+                                 required: true %>
+      </div>
+      
       <div class="flex items-center gap-2">
         <%= loan_form.number_field :interest_rate,
                                  label: t("loans.form.interest_rate"),

app/views/loans/_overview.html.erb

@@ -2,7 +2,7 @@
 
 <div class="grid grid-cols-3 gap-2">
   <%= summary_card title: t(".original_principal") do %>
-    <%= format_money account.original_balance %>
+    <%= format_money account.loan.original_balance %>
   <% end %>
 
   <%= summary_card title: t(".remaining_principal") do %>

config/locales/views/loans/en.yml

@@ -6,6 +6,7 @@ en:
     form:
       interest_rate: Interest rate
       interest_rate_placeholder: '5.25'
+      initial_balance: Original loan balance
       rate_type: Rate type
       term_months: Term (months)
       term_months_placeholder: '360'

db/migrate/20250405210514_add_initial_balance_field.rb

@@ -0,0 +1,5 @@
+class AddInitialBalanceField < ActiveRecord::Migration[7.2]
+  def change
+    add_column :loans, :initial_balance, :decimal, precision: 19, scale: 4
+  end
+end

db/schema.rb

@@ -378,6 +378,7 @@ ActiveRecord::Schema[7.2].define(version: 2025_04_11_140604) do
     t.string "rate_type"
     t.decimal "interest_rate", precision: 10, scale: 3
     t.integer "term_months"
+    t.decimal "initial_balance", precision: 19, scale: 4
   end
 
   create_table "merchants", id: :uuid, default: -> { "gen_random_uuid()" }, force: :cascade do |t|

test/controllers/loans_controller_test.rb

@@ -22,7 +22,8 @@ class LoansControllerTest < ActionDispatch::IntegrationTest
           accountable_attributes: {
             interest_rate: 5.5,
             term_months: 60,
-            rate_type: "fixed"
+            rate_type: "fixed",
+            initial_balance: 50000
           }
         }
       }
@@ -36,6 +37,7 @@ class LoansControllerTest < ActionDispatch::IntegrationTest
     assert_equal 5.5, created_account.accountable.interest_rate
     assert_equal 60, created_account.accountable.term_months
     assert_equal "fixed", created_account.accountable.rate_type
+    assert_equal 50000, created_account.accountable.initial_balance
 
     assert_redirected_to created_account
     assert_equal "Loan account created", flash[:notice]
@@ -54,7 +56,8 @@ class LoansControllerTest < ActionDispatch::IntegrationTest
             id: @account.accountable_id,
             interest_rate: 4.5,
             term_months: 48,
-            rate_type: "fixed"
+            rate_type: "fixed",
+            initial_balance: 48000
           }
         }
       }
@@ -67,6 +70,7 @@ class LoansControllerTest < ActionDispatch::IntegrationTest
     assert_equal 4.5, @account.accountable.interest_rate
     assert_equal 48, @account.accountable.term_months
     assert_equal "fixed", @account.accountable.rate_type
+    assert_equal 48000, @account.accountable.initial_balance
 
     assert_redirected_to @account
     assert_equal "Loan account updated", flash[:notice]

test/system/accounts_test.rb

@@ -59,6 +59,7 @@ class AccountsTest < ApplicationSystemTestCase
 
   test "can create loan account" do
     assert_account_created "Loan" do
+      fill_in "account[accountable_attributes][initial_balance]", with: 1000
       fill_in "Interest rate", with: 5.25
       select "Fixed", from: "Rate type"
       fill_in "Term (months)", with: 360