Darvas Box - Last Box Only

//
//author KıvanÇ @fr3762 on twitter
//creator Nicholas Darvas
//
//@version=6
study("DARVAS BOX - Last Box Only", overlay=true, shorttitle="DARVAS")

boxp = input.int(5, "BOX LENGTH", minval=1)

// Variables to track the last box's data
var float lastTopBox = na
var float lastBottomBox = na
var int lastBoxStartTime = na

LL = ta.lowest(low, boxp)
k1 = ta.highest(high, boxp)
k2 = ta.highest(high, boxp - 1)
k3 = ta.highest(high, boxp - 2)

NH = ta.valuewhen(high > k1[1], high, 0)
box1 = k3 < k2

// Check for a new box formation
if barssince(high > k1[1]) == boxp - 2 and box1 and NH != 0
    lastTopBox := NH
    lastBottomBox := LL
    lastBoxStartTime := bar_index

// Plot only the last box
plotshape(lastTopBox, style=shape.triangleup, location=location.abovebar, color=color.green, size=size.small, title="Top Box")
plotshape(lastBottomBox, style=shape.triangledown, location=location.belowbar, color=color.red, size=size.small, title="Bottom Box")


//Optional:  Visualize the box duration (for debugging/understanding)  -  requires adjustment for v6
//var line topLine = line.new(na, na, na, na)
//var line bottomLine = line.new(na, na, na, na)

//if not na(lastBoxStartTime)
//    line.set_x1(topLine, lastBoxStartTime - boxp + 1)
//    line.set_x2(topLine, lastBoxStartTime)
//    line.set_y1(topLine, lastBottomBox)
//    line.set_y2(topLine, lastTopBox)
    
//    line.set_x1(bottomLine, lastBoxStartTime - boxp + 1)
//    line.set_x2(bottomLine, lastBoxStartTime)
//    line.set_y1(bottomLine, lastBottomBox)
//    line.set_y2(bottomLine, lastBottomBox)