// This Pine Script™ code is subject to the terms of the Mozilla Public License 2.0
// https://mozilla.org/MPL/2.0/
// © QuanTAlib

//@version=6
indicator("TRIM: Trimmed Mean Moving Average", shorttitle="TRIM", overlay=true)

// @function Calculates the Trimmed Mean Moving Average.
//   Sorts the lookback window, discards the lowest and highest trimPct%
//   of values, and averages the remaining middle portion.
//   This robust estimator reduces the influence of outliers/spikes
//   while preserving more information than a pure median.
//   trimPct=0 → SMA, trimPct=50 → Median.
// @param src Series to smooth.
// @param period Window length. Must be >= 3.
// @param trimPct Percentage of values to trim from each tail (0-49). Default 10.
// @returns The trimmed mean value.
trim(series float src, simple int period, simple int trimPct) =>
    // Number of values to discard from each end
    int trimCount = math.max(int(period * trimPct / 100.0), 0)
    int keepCount = period - 2 * trimCount
    if keepCount < 1
        keepCount := 1
        trimCount := (period - 1) / 2

    // Collect values into array and sort
    float[] vals = array.new_float(period)
    for i = 0 to period - 1
        array.set(vals, i, nz(src[i]))
    array.sort(vals, order.ascending)

    // Average the middle portion
    float sum = 0.0
    for i = trimCount to trimCount + keepCount - 1
        sum += array.get(vals, i)
    sum / keepCount

// ── Inputs ──────────────────────────────────────────────
p = input.int(20, "Period", minval=3)
t = input.int(10, "Trim %", minval=0, maxval=49, tooltip="Percentage trimmed from each tail. 0=SMA, 50=Median")

// ── Calculation ─────────────────────────────────────────
result = trim(close, p, t)

// ── Plot ────────────────────────────────────────────────
plot(result, "TRIM", color=color.yellow, linewidth=2)