Stop Struggling with Volume weighted average price indicator Code

//@version=5
indicator("HorizonAI Custom VWAP", overlay=true, trust_level=true)

// Input parameters
anchor = input.string("Session", "Anchor Period", options=["Session", "Week", "Month"])
src = input.source(hlc3, "Source")
offset = input.int(0, "Offset", minval=-500, maxval=500)
stdev_mult = input.float(1.0, "Standard Deviation Multiplier", minval=0.1)

// Logic for resetting the VWAP based on anchor
is_new_period = switch anchor
    "Session" => timeframe.change("D")
    "Week"    => timeframe.change("W")
    "Month"   => timeframe.change("M")
    => false

// VWAP Calculations
var float sumSrcVol = 0.0
var float sumVol = 0.0
var float sumSrcSrcVol = 0.0

if is_new_period
    sumSrcVol := src * volume
    sumVol := volume
    sumSrcSrcVol := src * src * volume
else
    sumSrcVol += src * volume
    sumVol += volume
    sumSrcSrcVol += src * src * volume

vwap_value = sumSrcVol / sumVol
variance = (sumSrcSrcVol / sumVol) - math.pow(vwap_value, 2)
stdev = math.sqrt(math.max(0, variance))

upper_band = vwap_value + (stdev * stdev_mult)
lower_band = vwap_value - (stdev * stdev_mult)

// Dynamic Coloring
vwap_color = close > vwap_value ? color.green : color.red

// Plotting
plot(vwap_value, "VWAP", color=vwap_color, linewidth=2, offset=offset)
p1 = plot(upper_band, "Upper Band", color=color.new(color.gray, 50), offset=offset)
p2 = plot(lower_band, "Lower Band", color=color.new(color.gray, 50), offset=offset)
fill(p1, p2, color=color.new(vwap_color, 90), title="VWAP Ribbon")