True Trend Strength -Completed

//@version=3
study("True Trend Strength",overlay=false)
//
bc = input(false,title="Enable Bar Color")
len = input(15,title="Period")
//
buyPower1 = highest(high,len)
buyPower2 = lowest(low,len)[len]
x_15dayBuyPower = buyPower1-buyPower2

sellPower1 = highest(high,len)[len]
sellPower2 = lowest(low,len)
x_15daySellPower = sellPower1 - sellPower2

plot(x_15dayBuyPower,color=blue,title="Buyer Strength",transp=0,style=histogram,linewidth=3)
plot(x_15daySellPower,color=red,title="Seller Strength",transp=0,style=histogram,linewidth=3)
barcolor(not bc ? na: x_15dayBuyPower > x_15daySellPower ? green :red,title="barcolor")

alertcondition(x_15dayBuyPower, title='Buyer Strength', message='Buyer Strength!')
alertcondition(x_15daySellPower, title='Seller Strength', message='Seller Strength!')