import numpy as np
def barrier_labels(high, low, close, atr, sl_mult, tp_mult, horizon, spread):
    """Faithful port of CExpertSignalAIBase::TripleBarrierLabel.
    Arrays are CHRONOLOGICAL (index 0 = oldest). Stop is tested before target on each
    side, so a bar spanning both barriers scores as the loss. Returns 0=Buy 1=Sell 2=Neutral,
    plus a timed-out mask (neither side resolved at all)."""
    n = len(close)
    lab = np.full(n, 2, dtype=np.int8)
    timed = np.zeros(n, dtype=bool)
    valid = np.zeros(n, dtype=bool)
    for j in range(n):
        a = atr[j]
        if not np.isfinite(a) or a <= 0: continue
        last = min(j + horizon, n - 1)
        if last <= j: continue
        e = close[j]; risk = sl_mult*a; rew = tp_mult*a
        lTp = e + spread + rew; lSl = e + spread - risk
        sTp = e - rew - spread; sSl = e + risk - spread
        lW=lL=sW=sL=False
        hs = high[j+1:last+1]; ls = low[j+1:last+1]
        for k in range(len(hs)):
            hi=hs[k]; lo=ls[k]
            if not (lW or lL):
                if lo <= lSl: lL=True
                elif hi >= lTp: lW=True
            if not (sW or sL):
                if hi >= sSl: sL=True
                elif lo <= sTp: sW=True
            if (lW or lL) and (sW or sL): break
        valid[j]=True
        if lW and not sW: lab[j]=0
        elif sW and not lW: lab[j]=1
        else:
            lab[j]=2
            timed[j] = not (lW or lL or sW or sL)
    return lab, timed, valid