Bull-Bear Power Ratio (BRAR)

// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("Bull-Bear Power Ratio (BRAR)", "BRAR", overlay=false)

//@function Calculates BRAR (BR and AR) sentiment oscillator
//@param period Rolling window length for summation (default 26)
//@returns tuple [br, ar] where BR measures buying pressure vs previous close,
//         AR measures selling pressure vs today's open. Both scaled x100.
//@optimized Uses 4 circular buffers for O(1) per-bar complexity
brar(simple int period) =>
    if period <= 0
        runtime.error("Period must be greater than 0")
    if period > 5000
        runtime.error("Period exceeds maximum of 5000")

    float prevClose = nz(close[1], open)

    float brNum = math.max(0.0, high - prevClose)
    float brDen = math.max(0.0, prevClose - low)
    float arNum = math.max(0.0, high - open)
    float arDen = math.max(0.0, open - low)

    var array<float> brNumBuf = array.new_float(period, 0.0)
    var array<float> brDenBuf = array.new_float(period, 0.0)
    var array<float> arNumBuf = array.new_float(period, 0.0)
    var array<float> arDenBuf = array.new_float(period, 0.0)
    var int idx = 0
    var float brNumSum = 0.0
    var float brDenSum = 0.0
    var float arNumSum = 0.0
    var float arDenSum = 0.0

    brNumSum -= array.get(brNumBuf, idx)
    brDenSum -= array.get(brDenBuf, idx)
    arNumSum -= array.get(arNumBuf, idx)
    arDenSum -= array.get(arDenBuf, idx)

    array.set(brNumBuf, idx, brNum)
    array.set(brDenBuf, idx, brDen)
    array.set(arNumBuf, idx, arNum)
    array.set(arDenBuf, idx, arDen)

    brNumSum += brNum
    brDenSum += brDen
    arNumSum += arNum
    arDenSum += arDen

    idx := (idx + 1) % period

    float br = brDenSum != 0.0 ? brNumSum / brDenSum * 100.0 : 100.0
    float ar = arDenSum != 0.0 ? arNumSum / arDenSum * 100.0 : 100.0

    [br, ar]

// ---------- Main loop ----------

// Inputs
i_period = input.int(26, "Period", minval=1, maxval=5000, tooltip="Rolling window for summation (traditional: 26)")

// Calculation
[br_value, ar_value] = brar(i_period)

// Plot
plot(br_value, "BR", color.new(color.aqua, 0), 2)
plot(ar_value, "AR", color.new(color.yellow, 0), 2)
hline(100, "Equilibrium", color=color.gray, linestyle=hline.style_dotted)