Fetch FX rates from Banking Circle API - supports both standard and held rates

fx_rate.rb

class FetchBankingCircleFxRateScript < BaseScript
  def self.options(args)
    {
      currency_pair: "GBP/USD",
      valid_for_minutes: nil,
      amount: "1000.00",
    }.tap do |result|
      OptionParser.new do |parser|
        parser.on("-cPAIR", "--currency-pair=PAIR", String, "Currency pair (e.g., GBP/USD, EUR/PLN)")
        parser.on("-vMINUTES", "--valid-for=MINUTES", Integer, "Hold rate for N minutes (optional)")
        parser.on("-aAMOUNT", "--amount=AMOUNT", String, "Amount to quote (default: 1000.00)")
      end.parse!(args, into: result)
    end
  end

  def call
    currency_pair = options[:"currency-pair"] || options[:currency_pair] || "GBP/USD"
    valid_for = options[:"valid-for"] || options[:valid_for_minutes]
    amount = options[:amount] || "1000.00"

    base_ccy, counter_ccy = currency_pair.split("/")

    puts "=" * 70
    puts "BANKING CIRCLE FX RATE"
    puts "=" * 70
    puts "Currency Pair: #{base_ccy}/#{counter_ccy}"
    puts "Amount: #{amount} #{base_ccy}"
    puts "Rate Type: #{valid_for ? "#{valid_for}-minute held" : "Short-lived (standard)"}"
    puts "-" * 70

    check_credentials!

    start_time = Time.current
    service = fetch_rate(base_ccy, counter_ccy, amount, valid_for)
    response_time = ((Time.current - start_time) * 1000).round(0)

    if service.success? && service.is_tradable?
      display_rate(service, amount, base_ccy, counter_ccy, response_time, start_time)
    else
      puts "Error: #{service.quote_type || "Request failed"}"
      puts service.response&.body
    end
  rescue => e
    puts "Error: #{e.message}"
  end

  private

  def check_credentials!
    ["BC_USER_NAME", "BC_PASSWORD", "BC_CERTIFICATE_FILEPATH"].each do |var|
      if ENV[var].nil? || ENV[var].empty?
        raise "#{var} not set"
      end
    end
  end

  def fetch_rate(base_ccy, counter_ccy, amount, valid_for)
    if valid_for
      fetch_held_rate(base_ccy, counter_ccy, amount, valid_for)
    else
      fetch_standard_rate(base_ccy, counter_ccy, amount)
    end
  end

  def fetch_standard_rate(base_ccy, counter_ccy, amount)
    service = BankingCircleConnector::QuotesService.new(base_ccy, counter_ccy, base_ccy, amount)
    service.go!
    service
  end

  def fetch_held_rate(base_ccy, counter_ccy, amount, valid_for)
    service = BankingCircleConnector::QuotesService.new(base_ccy, counter_ccy, base_ccy, amount)

    service.instance_variable_set(:@base_ccy, base_ccy)
    service.instance_variable_set(:@counter_ccy, counter_ccy)
    service.instance_variable_set(:@specified_currency, base_ccy)
    service.instance_variable_set(:@specified_amount, amount)
    service.instance_variable_set(:@valid_for, valid_for)

    service.instance_eval do
      def go!
        initialize_client do |client|
          endpoint = "#{base_url}/fx/rates/held-rates/#{@base_ccy}/#{@counter_ccy}"
          @response = client.get(endpoint) do |req|
            req.headers = { "Content-Type" => "application/json", "Authorization" => "Bearer #{token}" }
            req.params = {
              "amountCurrency" => @specified_currency,
              "amount" => @specified_amount,
              "validForMinutes" => @valid_for,
            }
          end
        end

        if success?
          @quote_type = json_response["quoteType"]
          @currency_pair = json_response["currencyPair"]
          @rate_bid = json_response["exchangeRateBid"]
          @rate_offer = json_response["exchangeRateAsk"]
          @expiry_time = json_response["expiryTime"].to_time if json_response["expiryTime"]
          @quote_id = json_response["quoteId"]
        end
      end
    end

    service.go!
    service
  end

  def display_rate(service, amount, base_ccy, counter_ccy, response_time, start_time)
    bid = service.rate_bid.to_d
    offer = service.rate_offer.to_d
    spread = offer - bid
    duration = service.expiry_time - start_time

    puts "Status:    #{service.quote_type}"
    puts "Bid:       #{bid}"
    puts "Offer:     #{offer}"
    puts "Spread:    #{spread} (#{((spread / ((bid + offer) / 2)) * 100).round(4)}%)"
    puts "Expires:   #{service.expiry_time.strftime("%H:%M:%S")} (#{duration.round(0)}s / #{(duration / 60).round(1)}min)"
    puts "Quote ID:  #{service.quote_id}"
    puts "Response:  #{response_time}ms"
    puts ""
    puts "Value:     #{amount} #{base_ccy} = #{(amount.to_d * offer).round(2)} #{counter_ccy}"
  end
end