# indie:lang_version = 5
from math import isnan, nan, log
from indie import indicator, format, param, level, color, plot, MutSeriesF
from indie.algorithms import Highest, Lowest
from indie.math import divide


def nan_to_zero(val: float) -> float:
    return 0 if isnan(val) else val


def round(val: float) -> float:
    if val > 0.99:
        val = 0.999
    elif val < -0.99:
        val = -0.999
    return val


@indicator('Fisher', format=format.PRICE)  # Fisher Transform
@param.int('length', default=9, min=1)
@level(-1.5, line_color=color.RED, title='-1.5')
@level(-0.75, line_color=color.GRAY, title='-0.75')
@level(0, line_color=color.RED, title='0')
@level(0.75, line_color=color.GRAY, title='0.75')
@level(1.5, line_color=color.RED, title='1.5')
@plot.line(color=color.BLUE, title='Fisher')
@plot.line(color=color.MAROON, title='Trigger')
def Main(self, length):
    high = Highest.new(self.hl2, length)[0]
    low = Lowest.new(self.hl2, length)[0]

    value = MutSeriesF.new(init=0)
    value[0] = round(0.66 * (divide(self.hl2[0] - low, high - low) - 0.5) + \
                     0.67 * nan_to_zero(value[1]))
    fish = MutSeriesF.new(init=nan)
    fish[0] = 0.5 * log(divide(1 + value[0], 1 - value[0])) + 0.5 * nan_to_zero(fish[1])
    return fish[0], fish[1]