Bull Bear VOL

//@version=5
indicator('Bull Bear VOL', overlay=false, timeframe='5')

TimeFrame = input.timeframe('D', title='Khoang Thoi Gian Kiem Dinh')
Source = input(hlc3, title='Pivot')
start = request.security('', TimeFrame, time)
mavol = request.security('', TimeFrame, ta.sma(volume, 99))

//------------------------------------------------
change_1 = ta.change(start)
newSession = change_1 > 0 ? 1 : 0

value = high - low
buy = Source - low
sell = high - Source

buyer = volume * (buy / value)
seller = volume * (sell / value)

cal(a, b) =>
    sum = 0.0
    if a == 1
        sum := b
        sum
    if a == 0
        sum := sum[1] + b
        sum
    sum
bullis = cal(newSession, buyer)
bearis = cal(newSession, seller)
MR = bullis / bearis
mfi = math.pow(10, math.log10(mavol)) / 2 - math.pow(10, math.log10(mavol)) / (1 + MR)
winner = bullis - bearis
plot(mfi, color=barstate.isconfirmed and mfi > 0 ? color.aqua : barstate.isconfirmed and mfi < 0 ? color.orange : color.gray, title='Buy Sell MFI ')
plot(winner, color=barstate.isconfirmed and winner > 0 ? color.lime : barstate.isconfirmed and winner < 0 ? color.red : color.gray, title='Buy Sell Winner ')
plot(0, color=color.new(color.gray, 0))

London = input.session('0300-1200', title='Khung gio Phien Au UTC')
NY = input.session('0800-1700', title='Khung gio Phien My UTC')

bgcolor(time(timeframe.period, London) ? color.green : na, title='London Session', transp=90)
bgcolor(time(timeframe.period, NY) ? color.red : na, title='New York Session', transp=90)
bgcolor(newSession ? color.white : na, title='Begin Calculate Time', transp=90)
//bgcolor(Asian, title="Asian")