# indie:lang_version = 5
from indie import indicator, param, source, plot, color, MutSeriesF
from indie.algorithms import Ma, Tr, Atr, Rma


@indicator('KC', overlay_main_pane=True)  # Keltner Channels
@param.int('length', default=20, min=1)
@param.float('mult', default=2.0, title='Multiplier')
@param.source('src', default=source.CLOSE, title='Source')
@param.bool('exp', default=True, title='Use Exponential MA')
@param.str('bands_style', default='Average True Range', title='Bands Style',
           options=['Average True Range', 'True Range', 'Range'])
@param.int('atr_length', default=10, min=1, title='ATR Length')
@plot.line('lower', color=color.BLUE, title='Lower')
@plot.line(color=color.BLUE, title='Basis')
@plot.line('upper', color=color.BLUE, title='Upper')
@plot.fill('lower', 'upper', color=color.AQUA(0.05), title='Background')
def Main(self, length, mult, src, exp, bands_style, atr_length):
    ma = Ma.new(src, length, 'EMA' if exp else 'SMA')[0]
    range_ma = 0.0
    if bands_style == 'True Range':
        range_ma = Tr.new(True)[0]
    elif bands_style == 'Average True Range':
        range_ma = Atr.new(atr_length)[0]
    else:  # bands_style == 'Range'
        range_ma = Rma.new(MutSeriesF.new(self.high[0] - self.low[0]), length)[0]
    upper = ma + range_ma * mult
    lower = ma - range_ma * mult
    return lower, ma, upper, plot.Fill()