// @version=4
// © ZenAndTheArtOfTrading
study("Highest High Within Timezone", overlay=true)

// Define time window as an input function
timezone = input(title="Timezone To Highlight", type=input.session, defval="1000-1500")
lookback = input(title="Lookback Period", type=input.integer, defval=10)

// Convert input timezone into milisecond time
t = time(timeframe.period, timezone)

// Check if current bar is within that milisecond time window
barIsWithinTimezone = na(t) ? false : true

// Get the highest high of the past X candles ONLY if the current bar is within the time window
highestHighWithinSession = valuewhen(barIsWithinTimezone, highest(high, lookback), 1)

// Get the lowest low of the past X candles ONLY if the current bar is within the time window
lowestLowWithinSession = valuewhen(barIsWithinTimezone, lowest(low, lookback), 1)

// Plot highs/lows
plot(highestHighWithinSession, color=color.red)
plot(lowestLowWithinSession, color=color.blue)
bgcolor(barIsWithinTimezone ? color.black : na, transp=90)