Transfer and Payment auto-matching, model and UI improvements (#1585)

* Transfer data model migration

* Transfers and payment modeling and UI improvements

* Fix CI

* Transfer matching flow

* Better UI for transfers

* Auto transfer matching, approve, reject flow

* Mark transfers created from form as confirmed

* Account filtering

* Excluded rejected transfers from calculations

* Calculation tweaks with transfer exclusions

* Clean up migration

app/models/transfer.rb

@@ -0,0 +1,139 @@
+class Transfer < ApplicationRecord
+  belongs_to :inflow_transaction, class_name: "Account::Transaction"
+  belongs_to :outflow_transaction, class_name: "Account::Transaction"
+
+  enum :status, { pending: "pending", confirmed: "confirmed", rejected: "rejected" }
+
+  validate :transfer_has_different_accounts
+  validate :transfer_has_opposite_amounts
+  validate :transfer_within_date_range
+
+  class << self
+    def from_accounts(from_account:, to_account:, date:, amount:)
+      # Attempt to convert the amount to the to_account's currency.
+      # If the conversion fails, use the original amount.
+      converted_amount = begin
+        Money.new(amount.abs, from_account.currency).exchange_to(to_account.currency)
+      rescue Money::ConversionError
+        Money.new(amount.abs, from_account.currency)
+      end
+
+      new(
+        inflow_transaction: Account::Transaction.new(
+          entry: to_account.entries.build(
+            amount: converted_amount.amount.abs * -1,
+            currency: converted_amount.currency.iso_code,
+            date: date,
+            name: "Transfer from #{from_account.name}",
+            entryable: Account::Transaction.new
+          )
+        ),
+        outflow_transaction: Account::Transaction.new(
+          entry: from_account.entries.build(
+            amount: amount.abs,
+            currency: from_account.currency,
+            date: date,
+            name: "Transfer to #{to_account.name}",
+            entryable: Account::Transaction.new
+          )
+        ),
+        status: "confirmed"
+      )
+    end
+
+    def auto_match_for_account(account)
+      matches = account.entries.account_transactions.joins("
+        JOIN account_entries ae2 ON
+          account_entries.amount = -ae2.amount AND
+          account_entries.currency = ae2.currency AND
+          account_entries.account_id <> ae2.account_id AND
+          ABS(account_entries.date - ae2.date) <= 4
+      ").select(
+        "account_entries.id",
+        "account_entries.entryable_id AS e1_entryable_id",
+        "ae2.entryable_id AS e2_entryable_id",
+        "account_entries.amount AS e1_amount",
+        "ae2.amount AS e2_amount"
+      )
+
+      Transfer.transaction do
+        matches.each do |match|
+          inflow = match.e1_amount.negative? ? match.e1_entryable_id : match.e2_entryable_id
+          outflow = match.e1_amount.negative? ? match.e2_entryable_id : match.e1_entryable_id
+
+          # Skip all rejected, or already matched transfers
+          next if Transfer.exists?(
+            inflow_transaction_id: inflow,
+            outflow_transaction_id: outflow
+          )
+
+          Transfer.create!(
+            inflow_transaction_id: inflow,
+            outflow_transaction_id: outflow
+          )
+        end
+      end
+    end
+  end
+
+  def sync_account_later
+    inflow_transaction.entry.sync_account_later
+    outflow_transaction.entry.sync_account_later
+  end
+
+  def belongs_to_family?(family)
+    family.transactions.include?(inflow_transaction)
+  end
+
+  def to_account
+    inflow_transaction.entry.account
+  end
+
+  def from_account
+    outflow_transaction.entry.account
+  end
+
+  def amount_abs
+    inflow_transaction.entry.amount_money.abs
+  end
+
+  def name
+    if payment?
+      I18n.t("transfer.payment_name", to_account: to_account.name)
+    else
+      I18n.t("transfer.name", to_account: to_account.name)
+    end
+  end
+
+  def payment?
+    to_account.liability?
+  end
+
+  private
+    def transfer_has_different_accounts
+      return unless inflow_transaction.present? && outflow_transaction.present?
+      errors.add(:base, :must_be_from_different_accounts) if inflow_transaction.entry.account == outflow_transaction.entry.account
+    end
+
+    def transfer_has_opposite_amounts
+      return unless inflow_transaction.present? && outflow_transaction.present?
+
+      inflow_amount = inflow_transaction.entry.amount
+      outflow_amount = outflow_transaction.entry.amount
+
+      if inflow_transaction.entry.currency == outflow_transaction.entry.currency
+        # For same currency, amounts must be exactly opposite
+        errors.add(:base, :must_have_opposite_amounts) if inflow_amount + outflow_amount != 0
+      else
+        # For different currencies, just check the signs are opposite
+        errors.add(:base, :must_have_opposite_amounts) unless inflow_amount.negative? && outflow_amount.positive?
+      end
+    end
+
+    def transfer_within_date_range
+      return unless inflow_transaction.present? && outflow_transaction.present?
+
+      date_diff = (inflow_transaction.entry.date - outflow_transaction.entry.date).abs
+      errors.add(:base, :must_be_within_date_range) if date_diff > 4
+    end
+end