module RQRCode::Export::ANSI

def as_ansi(options = {})
  options = {
    light: "\033[47m",
    dark: "\033[40m",
    fill_character: "  ",
    quiet_zone_size: 4
  }.merge(options)
  normal = "\033[m\n"
  light = options.fetch(:light)
  dark = options.fetch(:dark)
  fill_character = options.fetch(:fill_character)
  quiet_zone_size = options.fetch(:quiet_zone_size)
  output = []
  @qrcode.modules.each_index do |c|
    # start row with quiet zone
    row = light + fill_character * quiet_zone_size
    previous_dark = false
    @qrcode.modules.each_index do |r|
      if @qrcode.checked?(c, r)
        if previous_dark != true
          row << dark
          previous_dark = true
        end
      elsif previous_dark != false
        # light
        row << light
        previous_dark = false
      end
      row << fill_character
    end
    # add quiet zone
    if previous_dark != false
      row << light
    end
    row << fill_character * quiet_zone_size
    # always end with reset and newline
    row << normal
    output << row
  end
  # count the row width so we can add quiet zone rows
  width = output.first.scan(fill_character).length
  quiet_row = light + fill_character * width + normal
  quiet_rows = quiet_row * quiet_zone_size
  quiet_rows + output.join + quiet_rows
end