Maybe/test/models/family/auto_transfer_matchable_test.rb

require "test_helper"

class Family::AutoTransferMatchableTest < ActiveSupport::TestCase
  include EntriesTestHelper

  setup do
    @family = families(:dylan_family)
    @depository = accounts(:depository)
    @credit_card = accounts(:credit_card)
  end

  test "auto-matches transfers" do
    outflow_entry = create_transaction(date: 1.day.ago.to_date, account: @depository, amount: 500)
    inflow_entry = create_transaction(date: Date.current, account: @credit_card, amount: -500)

    assert_difference -> { Transfer.count } => 1 do
      @family.auto_match_transfers!
    end
  end

  test "auto-matches multi-currency transfers" do
    load_exchange_prices
    create_transaction(date: 1.day.ago.to_date, account: @depository, amount: 500)
    create_transaction(date: Date.current, account: @credit_card, amount: -700, currency: "CAD")

    assert_difference -> { Transfer.count } => 1 do
      @family.auto_match_transfers!
    end

    # test match within lower 5% bound
    create_transaction(date: 1.day.ago.to_date, account: @depository, amount: 1000)
    create_transaction(date: Date.current, account: @credit_card, amount: -1330, currency: "CAD")

    assert_difference -> { Transfer.count } => 1 do
      @family.auto_match_transfers!
    end

    # test match within upper 5% bound
    create_transaction(date: 1.day.ago.to_date, account: @depository, amount: 1500)
    create_transaction(date: Date.current, account: @credit_card, amount: -2189, currency: "CAD")

    assert_difference -> { Transfer.count } => 1 do
      @family.auto_match_transfers!
    end

    # test no match outside of slippage tolerance
    create_transaction(date: 1.day.ago.to_date, account: @depository, amount: 1000)
    create_transaction(date: Date.current, account: @credit_card, amount: -1320, currency: "CAD")

    assert_difference -> { Transfer.count } => 0 do
      @family.auto_match_transfers!
    end
  end

  test "only matches inflow with correct currency when duplicate amounts exist" do
    load_exchange_prices
    create_transaction(date: 1.day.ago.to_date, account: @depository, amount: 500)
    create_transaction(date: Date.current, account: @credit_card, amount: -500, currency: "CAD")
    create_transaction(date: Date.current, account: @credit_card, amount: -500)

    assert_difference -> { Transfer.count } => 1 do
      @family.auto_match_transfers!
    end
  end

  # In this scenario, our matching logic should find 4 potential matches.  These matches should be ranked based on
  # days apart, then de-duplicated so that we aren't auto-matching the same transaction across multiple transfers.
  test "when 2 options exist, only auto-match one at a time, ranked by days apart" do
    yesterday_outflow = create_transaction(date: 1.day.ago.to_date, account: @depository, amount: 500)
    yesterday_inflow = create_transaction(date: 1.day.ago.to_date, account: @credit_card, amount: -500)

    today_outflow = create_transaction(date: Date.current, account: @depository, amount: 500)
    today_inflow = create_transaction(date: Date.current, account: @credit_card, amount: -500)

    assert_difference -> { Transfer.count } => 2 do
      @family.auto_match_transfers!
    end
  end

  test "does not auto-match any transfers that have been rejected by user already" do
    outflow = create_transaction(date: Date.current, account: @depository, amount: 500)
    inflow = create_transaction(date: Date.current, account: @credit_card, amount: -500)

    RejectedTransfer.create!(inflow_transaction_id: inflow.entryable_id, outflow_transaction_id: outflow.entryable_id)

    assert_no_difference -> { Transfer.count } do
      @family.auto_match_transfers!
    end
  end

  test "does not consider inactive accounts when matching transfers" do
    @depository.update!(is_active: false)

    outflow = create_transaction(date: Date.current, account: @depository, amount: 500)
    inflow = create_transaction(date: Date.current, account: @credit_card, amount: -500)

    assert_no_difference -> { Transfer.count } do
      @family.auto_match_transfers!
    end
  end

  test "does not match transactions outside the 4-day window" do
    create_transaction(date: 10.days.ago.to_date, account: @depository, amount: 500)
    create_transaction(date: Date.current, account: @credit_card, amount: -500)

    assert_no_difference -> { Transfer.count } do
      @family.auto_match_transfers!
    end
  end

  test "does not match multi-currency transfer with missing exchange rate" do
    create_transaction(date: Date.current, account: @depository, amount: 500)
    create_transaction(date: Date.current, account: @credit_card, amount: -700, currency: "GBP")

    assert_no_difference -> { Transfer.count } do
      @family.auto_match_transfers!
    end
  end

  private
    def load_exchange_prices
      rates = {
        4.days.ago.to_date => 1.36,
        3.days.ago.to_date => 1.37,
        2.days.ago.to_date => 1.38,
        1.day.ago.to_date  => 1.39,
        Date.current => 1.40
      }

      rates.each do |date, rate|
        # USD to CAD
        ExchangeRate.create!(
          from_currency: "USD",
          to_currency: "CAD",
          date: date,
          rate: rate
        )

        # CAD to USD (inverse)
        ExchangeRate.create!(
          from_currency: "CAD",
          to_currency: "USD",
          date: date,
          rate: (1.0 / rate).round(6)
        )
      end
    end
end