USD ACB Calculator for CAD

acb_calculator.rb

require 'csv'
require 'bigdecimal'
require 'byebug'

class Transaction
  attr_reader :date, :description, :debit_amount, :credit_amount, :balance

  attr_accessor :exchange_rate

  def initialize(date, description, debit_amount, credit_amount, exchange_rate, date_format:"%m/%d/%Y")
    @date = Date.strptime(date, date_format)
    @description = description.strip
    @debit_amount = BigDecimal(debit_amount || "0")
    @credit_amount = BigDecimal(credit_amount || "0")

    if exchange_rate
      @exchange_rate = BigDecimal(exchange_rate || "1")
    end
  end

  def debit_amount_cad
    debit_amount * exchange_rate
  end

  def credit_amount_cad
    credit_amount * exchange_rate
  end
end

exchange_rates = CSV.read("exchange-rates.csv").to_h

transactions = []
current_balance_cad = BigDecimal(0)
current_balance_usd = BigDecimal(0)
current_acb = BigDecimal(0)

total_credits_usd = BigDecimal(0)
total_credits_cad = BigDecimal(0)

total_debits_usd = BigDecimal(0)
total_debits_cad = BigDecimal(0)

capital_gains = Hash.new do |h, k|
  h[k] = BigDecimal(0)
end

CSV.foreach("usd-transactions.csv") do |row|
  transaction = Transaction.new(*row)

  current_exchange_rate = exchange_rates[transaction.date.to_s]
  if BigDecimal(current_exchange_rate) <= 1
    debugger
  end
  transaction.exchange_rate = BigDecimal(current_exchange_rate)


  if transaction.credit_amount > 0
    current_balance_usd += transaction.credit_amount
    current_balance_cad += transaction.credit_amount_cad
    current_acb = current_balance_cad / current_balance_usd

    total_credits_usd += transaction.credit_amount
    total_credits_cad += transaction.credit_amount_cad
  else
    current_balance_cad -= transaction.debit_amount * current_acb
    current_balance_usd -= transaction.debit_amount

    transaction_gain_amount = transaction.debit_amount * (transaction.exchange_rate - current_acb)
    capital_gains[transaction.date.year] += transaction_gain_amount

    total_debits_usd += transaction.debit_amount
    total_debits_cad += transaction.debit_amount_cad

    puts "Transaction Debit Amount: #{transaction.debit_amount.to_f}"
    puts "Transaction Gain: #{transaction_gain_amount.to_f}"
  end

  puts "Transaction Date: #{transaction.date}"
  puts "Transaction Exchange Rate: #{transaction.exchange_rate.to_f}"
  puts "Current ACB: #{current_acb.to_f}"
  puts "Current Balance CAD: #{current_balance_cad.to_f}"
  puts "Current Balance USD: #{current_balance_usd.to_f}"
  puts "Current Capital Gains: #{capital_gains.map { |y,v| "#{y}: #{v.to_f}"}}"
  puts ""

  transactions << transaction
end

if ENV['DEBUG'] != ""
  debugger
end

puts "Total transactions: #{transactions.size}"
puts ""
puts "Total debits USD: #{total_debits_usd.to_f}"
puts "Total credits USD: #{total_credits_usd.to_f}"
puts ""
puts "Total debits CAD: #{total_debits_cad.to_f}"
puts "Total credits CAD: #{total_credits_cad.to_f}"
puts ""
puts "Final balance: #{transactions.last.balance.to_f}"