class Infobar::Trend

def arrow
  lr = MoreMath::LinearRegression.new(@values)
  case
  when lr.slope_zero?
    @symbols[1]
  when lr.a > 0
    @symbols[2]
  else
    @symbols[0]
  end.to_s
end

def initialize(values, symbols: %i[ ↘ → ↗ ])
  @values  = values
  @symbols = symbols
  @string  = arrow
end

def to_s
  @string
end