//@version=5
indicator("Custom Volume Profile Histogram", overlay=true, max_boxes_count=500)

// ─── Inputs ───────────────────────────────────────────────
barsBack   = input.int(100, "Bars Back", minval=10)
rows       = input.int(50, "Resolution (rows)", minval=10)
showVAHVAL = input.bool(true, "Show VAH/VAL/POC")

// ─── Calculate Range ──────────────────────────────────────
highestPrice = ta.highest(high, barsBack)
lowestPrice  = ta.lowest(low, barsBack)

range = highestPrice - lowestPrice
step  = range / rows

// ─── Initialize Arrays ────────────────────────────────────
var volumeBins = array.new_float(rows, 0.0)

// Reset bins each bar
if barstate.islast
    array.fill(volumeBins, 0.0)
    for i = 0 to barsBack - 1
        barHigh  = high[i]
        barLow   = low[i]
        barVol   = volume[i]
        
        // Distribute volume across bins touched by bar
        for r = 0 to rows - 1
            binLow  = lowestPrice + r * step
            binHigh = binLow + step
            overlap = math.max(0, math.min(barHigh, binHigh) - math.max(barLow, binLow))
            if overlap > 0
                array.set(volumeBins, r, array.get(volumeBins, r) + barVol * (overlap / (barHigh - barLow + 1e-6)))

// ─── Find POC, VAH, VAL ───────────────────────────────────
maxVol = 0.0
pocIndex = 0
for r = 0 to rows - 1
    v = array.get(volumeBins, r)
    if v > maxVol
        maxVol := v
        pocIndex := r

pocPrice = lowestPrice + pocIndex * step + step/2

// Value Area (70% of volume)
totalVol = array.sum(volumeBins)
targetVol = totalVol * 0.7
cumVol = 0.0
lowIndex = pocIndex
highIndex = pocIndex
while cumVol < targetVol and (lowIndex > 0 or highIndex < rows-1)
    leftVol  = lowIndex > 0       ? array.get(volumeBins, lowIndex-1) : 0
    rightVol = highIndex < rows-1 ? array.get(volumeBins, highIndex+1) : 0
    if leftVol > rightVol
        lowIndex -= 1
        cumVol += leftVol
    else
        highIndex += 1
        cumVol += rightVol

valPrice = lowestPrice + lowIndex * step
vahPrice = lowestPrice + highIndex * step

// ─── Plot Histogram Rectangles ────────────────────────────
if barstate.islast
    for r = 0 to rows - 1
        binVol   = array.get(volumeBins, r)
        binPriceLow  = lowestPrice + r * step
        binPriceHigh = binPriceLow + step
        barWidth = math.round(1 + 40 * binVol / maxVol)   // scale width
        box.new(bar_index - barsBack, binPriceLow, bar_index - barsBack + barWidth, binPriceHigh,
                xloc=xloc.bar_index, bgcolor=color.new(color.blue, 70), border_color=color.new(color.blue, 100))

// ─── Plot VAH/VAL/POC ─────────────────────────────────────
if showVAHVAL and barstate.islast
    line.new(bar_index - barsBack, pocPrice, bar_index, pocPrice,
             xloc=xloc.bar_index, extend=extend.none, color=color.red, width=2)
    line.new(bar_index - barsBack, valPrice, bar_index, valPrice,
             xloc=xloc.bar_index, extend=extend.none, color=color.green, width=2)
    line.new(bar_index - barsBack, vahPrice, bar_index, vahPrice,
             xloc=xloc.bar_index, extend=extend.none, color=color.green, width=2)