Higher Highs & Lower Lows Stochastics (HHLLS)

// Licensed under the Apache License, Version 2.0
// © mihakralj
//@version=6
indicator("Higher Highs & Lower Lows Stochastics (HHLLS)", "HHLLS", overlay = false)

//@function Higher Highs & Lower Lows Stochastics — conditional stochastic oscillator
//          that fires only on higher highs (HHS) or lower lows (LLS), then smooths
//          with EMA.
//          Pipeline: SlidingWindow(H,L) → ConditionalStoch → EMA(period).
//          Output bounded [0, 100].
//@param h High price series
//@param l Low price series
//@param period Lookback and EMA smoothing period (>= 2)
//@returns [hhs, lls] — dual oscillator values
//@reference Apirine, V. (2016). "Higher Highs & Lower Lows."
//           Technical Analysis of Stocks & Commodities, Feb 2016.
//@optimized O(1) amortized per bar via ta.highest/ta.lowest
hhlls(series float h, series float l, simple int period) =>
    if period < 2
        runtime.error("Period must be at least 2")

    // --- Sliding window extremes ---
    float highestHigh = ta.highest(h, period)
    float lowestHigh  = ta.lowest(h, period)
    float highestLow  = ta.highest(l, period)
    float lowestLow   = ta.lowest(l, period)

    // --- Conditional stochastic: Higher High gate ---
    float hhRange = highestHigh - lowestHigh
    float hhRaw   = (h > nz(h[1]) and hhRange > 0) ? 100.0 * (h - lowestHigh) / hhRange : 0.0

    // --- Conditional stochastic: Lower Low gate ---
    float llRange = highestLow - lowestLow
    float llRaw   = (l < nz(l[1]) and llRange > 0) ? 100.0 * (highestLow - l) / llRange : 0.0

    // --- EMA smoothing ---
    float hhs = ta.ema(hhRaw, period)
    float lls = ta.ema(llRaw, period)

    [hhs, lls]

// ── Inputs ──
int p_period = input.int(20, "Period", minval = 2)

// ── Calculation ──
[hhs, lls] = hhlls(high, low, p_period)

// ── Plot ──
plot(hhs, "HHS", color.green, 2)
plot(lls, "LLS", color.red, 2)
hline(60, "Overbought", color.new(color.gray, 50), linestyle = hline.style_dotted)
hline(30, "Signal", color.gray, linestyle = hline.style_dashed)
hline(10, "Oversold", color.new(color.gray, 50), linestyle = hline.style_dotted)