alex_bank.rb

# frozen_string_literal: true
module EGPRates
  # Bank of Alexandria
  class AlexBank < EGPRates::Bank
    def initialize
      @sym = :AlexBank
      @uri = URI.parse('https://www.alexbank.com/En/Home/ExchangeRates')
    end

    # @return [Hash] of exchange rates for selling and buying
    #   {
    #     { sell: { SYM: rate }, { SYM: rate }, ... },
    #     { buy:  { SYM: rate }, { SYM: rate }, ... }
    #   }
    def exchange_rates
      @exchange_rates ||= parse(raw_exchange_rates)
    end

    private

    # Send the request to the URL and retrun raw data of the response
    # @return [Enumerator::Lazy] with the table row in HTML that evaluates to
    #   ["", "US Dollar", "", ..., "17.10000", "", "17.50000", ""]
    #   ["", "British Pound", "", ..., "21.12363", "", "21.60025", ""]
    #   ...
    #
    def raw_exchange_rates
      # AlexBank provide 17 currencies (and 1 <th>)
      table_rows = Oga.parse_html(response.body).css('.exchangerate-table tr')
      fail ResponseError, 'Unknown HTML' unless table_rows&.size == 18
      table_rows.lazy.drop(1).map(&:children).map do |cell|
        cell.map(&:text).map(&:strip)
      end
    end

    # Parse the #raw_exchange_rates returned in response
    # @param [Array] of the raw_data scraped
    # @return [Hash] of exchange rates for selling and buying
    #   {
    #     { sell: { SYM: rate }, { SYM: rate }, ... },
    #     { buy:  { SYM: rate }, { SYM: rate }, ... }
    #   }
    def parse(raw_data)
      raw_data.each_with_object(sell: {}, buy: {}) do |row, result|
        sell_rate = row[9].to_f
        buy_rate  = row[7].to_f
        currency  = currency_symbol(row[1])

        result[:sell][currency] = sell_rate
        result[:buy][currency]  = buy_rate
      end
    end
  end
end