// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("AOBV - Archer On-Balance Volume (AOBV)", "AOBV", overlay=false)

//@function Computes AOBV Fast and Slow from OBV using custom EMA calculations without helper functions.
//@param src (series float) Price source.
//@param vol (series float) Volume data.
//@returns ([float, float]) Tuple with AOBV Fast and AOBV Slow values.
//@optimized Beta precomputation for EMA warmup compensation
aobv(src, vol) =>
    var float prev_src = na
    safe_src = not na(src) ? src : (not na(prev_src) ? prev_src : 0)
    safe_vol = not na(vol) ? vol : 0
    safe_prev = not na(prev_src) ? prev_src : safe_src
    var float obv_val = 0.0
    obv_val := bar_index == 0 ? (safe_src > safe_prev ? safe_vol : safe_src < safe_prev ? -safe_vol : 0) : obv_val + (safe_src > safe_prev ? safe_vol : safe_src < safe_prev ? -safe_vol : 0)
    if not na(src)
        prev_src := src
    periods = array.from(4, 14)
    var emaArr = array.new_float(2, na)
    var eArr = array.new_float(2, 1.0)
    var warmupArr = array.new_bool(2, true)
    var betaArr = array.new_float(2, 0.0)
    resArr = array.new_float(2, na)
    for i = 0 to array.size(periods) - 1
        period = array.get(periods, i)
        alpha = 2.0 / (period + 1)
        beta = array.get(betaArr, i)
        if beta == 0.0
            beta := 1.0 - alpha
            array.set(betaArr, i, beta)
        ema_val = array.get(emaArr, i)
        if na(ema_val)
            ema_val := 0.0
            array.set(emaArr, i, ema_val)
            array.set(resArr, i, obv_val)
        else
            ema_val := alpha * (obv_val - ema_val) + ema_val
            array.set(emaArr, i, ema_val)
            if array.get(warmupArr, i)
                new_e = array.get(eArr, i) * beta
                array.set(eArr, i, new_e)
                c = 1.0 / (1.0 - new_e)
                array.set(resArr, i, c * ema_val)
                if new_e <= 1e-10
                    array.set(warmupArr, i, false)
            else
                array.set(resArr, i, ema_val)
    [array.get(resArr, 0), array.get(resArr, 1)]

// ---------- Inputs ----------
src = input.source(close, "Source")
vol = input.source(volume, "Volume")

// ---------- Calculations ----------
[aobvFast, aobvSlow] = aobv(src, vol)

// ---------- Plotting ----------
plot(aobvFast, "AOBV Fast", color.blue, linewidth=2)
plot(aobvSlow, "AOBV Slow", color.red, linewidth=2)