# indie:lang_version = 5
from indie import (
    indicator, MutSeriesF, algorithm, SeriesF, plot, 
    color, param, line_style)
from indie.algorithms import CumSum, Sma


@algorithm
def MySum(self, src: SeriesF, length: int) -> SeriesF:
    cs = CumSum.new(src)
    return MutSeriesF.new(cs[0] - cs[length])


@algorithm
def MySma(self, src: SeriesF, length: int) -> SeriesF:
    s = MySum.new(src, length)
    return MutSeriesF.new(s[0] / length)


@indicator("Sma with 'series' length", overlay_main_pane=True)
@param.int('short_len', default=12)
@param.int('long_len', default=24)
@plot.line(color=color.BLUE(alpha=0.65), line_width=7, id='#plot_0')
@plot.line(color=color.RED, id='#plot_1')
@plot.line(color=color.GREEN, id='#plot_2')
def Main(self, short_len, long_len):
    # The long and short `Sma`s are calculated here with the algorithm 
    # from the `indie.algorithms` standard library, they accept only 
    # non-series lengths and they are plotted to be a reference that 
    # proves that MySma gives correct results.
    short_sma = Sma.new(self.high, short_len)
    long_sma = Sma.new(self.high, long_len)
    
    length = short_len
    if long_sma[0] >= short_sma[0]:
        length = long_len
    # So, strictly speaking, `length` is not a series, but just a number.
    # But it is kinda series, because it may have different values on different bars.
    # NOTE: If you need a truly series length, wrap it with `MutSeriesF.new(length)`.
    
    return (
        MySma.new(self.high, length)[0], # Do not use indie.algorithms.Sma here, 
                                         # because `length` is not constant over 
                                         # different bars. You may try and see how 
                                         # indicator starts giving bad results.
        short_sma[0],
        long_sma[0], 
    )