Bollinger Bands Time

//  Bollinger bands that will remain fixed to a time interval. 
//
//  @author munkeefonix
//  https://www.tradingview.com/u/munkeefonix/
//
//  Input values:
//  Daily Interval: If checked then days are used for the interval.  If unchecked then minutes will be used.
//  Interval: The interval to use for the indicator. 
study(shorttitle="BB Time", title="Bollinger Bands Time", overlay=true)

_source = close

multIntra()=>(isintraday ? 1.0 : (isdaily ? 1440.0 : isweekly ? 10080.0 : 43320.0))
multDaily()=>multIntra() / 1440.0

_useDaily=input(false, "Daily Interval")
_t=input(60.0, "Interval", float, minval=1.0) / (_useDaily ? multDaily() : multIntra())

_length = input(20, minval=1, title="Length")
_mult = input(2.0, minval=0.001, maxval=50, title="Std Dev")

_lenScale = round(_length * _t / interval)
_basis = sma(_source, _lenScale)
_dev = _mult * stdev(_source, _lenScale)

_offset = round(input(0, type=float, title="Offset") * (_t / interval))


plot(_basis, color=black, title="Basis", linewidth=2, offset=_offset)
_p1 = plot(_basis + _dev, color=black, linewidth=1, offset=_offset, title="Upper")
_p2 = plot(_basis - _dev, color=black, linewidth=1, offset=_offset, title="Lower")
fill(_p1, _p2, color=black, transp=90, title="Fill")