class TransactionsReportBuilder
  attr_reader :from_date, :to_date
  IMPORTANT_SHORTCUTS = %w[BTC LTC ETH BCH].freeze
  def initialize(from_date, to_date)
    @from_date = from_date
    @to_date = to_date
  end

  def build_report
    result = []

    IMPORTANT_SHORTCUTS.each do |shortcut|
      result << [shortcut, sum_in_currency(shortcut)]
    end
    result << ['Total quantity', total_quantity]
    result << ['Others quantity', others_quantity]
    result << ['Total in ETH', total_in_eth]
    result << ['Total in USD', total_in_usd]
    first_row = []
    last_row = []
    result.each do |name, value|
      first_row << name
      last_row << value
    end
    [first_row, last_row]
  end

  def sum_in_currency(shortcut)
    currency_id = CryptoCurrency.find_by(shortcut: shortcut)
    Transaction.joins(:personal_address)
               .where('personal_addresses.crypto_currency_id = ?', currency_id)
               .where(updated_at: date_range)
               .sum(:amount)
  end

  def total_quantity
    transactions_in_date_range.count
  end

  def others_quantity
    other_ids = other_shortcuts.map { |sc| CryptoCurrency.find_by(shortcut: sc).id }
    transactions_in_date_range.where('personal_addresses.crypto_currency_id IN (?)', other_ids).count
  end

  def total_in_eth
    shortcuts = CryptoCurrency.pluck(:shortcut)
    shortcuts.map do |shortcut|
      sum_in_currency(shortcut) * Rate.actual_for_currency(shortcut)
    end.sum
  end

  def total_in_usd
    total_in_eth * Rate.actual_eth_to_usd
  end

  private

  def date_range
    (from_date..to_date)
  end

  def transactions_in_date_range
    Transaction.joins(:personal_address).where(updated_at: date_range)
  end

  def other_shortcuts
    CryptoCurrency.pluck(:shortcut) - IMPORTANT_SHORTCUTS
  end
end