Fibonacci calculator

Hi I am JBjay new in trading futures.
I have been using babypips fibonacci calculator with some reservation. You see the calculation is based on swing high (point A) and swing low(point B) without point C the closing price to plot the retracement levels of 61.8%, 50% and 38.3% together with the extension levels, which the user have to input the trend, up or down. Whereas the fibonacci calculator in has 3 levels of input, point A, B and C with a choice of either uptrend or downtrend.

  1. What is the basis of determining the trend? Uptrend or downtrend based on the prevailing general trend? Uptrend or downtrend based on the daily price movements? What is there is uncertainty example a doji - do we use the previous trend as our marker?
    Thanks for your input and answers.