SELECT *, bar(value, 0, 100, 20) as value_bar 
FROM trends_with_gaps
ORDER BY date WITH FILL STEP 1

SELECT
  groupArray(date) dt_arr,
  groupArray(value) value_arr,
  arrayFill(x -> x.1 > 0, arrayZip(value_arr, dt_arr)) value_lower,
  arrayReverseFill(x -> x.1 > 0, arrayZip(value_arr, dt_arr)) value_upper,
  arrayMap((l, u, v, dt) ->
      if(v > 0,
        v,
        l.1 + ((u.1 - l.1) / (u.2 - l.2) * (dt - l.2))
      ), value_lower, value_upper, value_arr, dt_arr) AS value_interpolated
FROM trends_with_gaps

SELECT
    date,
    value,
    value_interpolated,
    bar(value_interpolated, 0, 100, 20) as value_interpolated_bar 
FROM interpolation
ARRAY JOIN dt_arr AS date, value_interpolated, value_arr AS value