Alternating KAMA-MACD Buy/Sell Triangles

//version=6
indicator("Alternating KAMA-MACD Buy/Sell Triangles", overlay=true)

// === Inputs ===
fastLen = input.int(10, "Fast KAMA Length", minval=2)
slowLen = input.int(30, "Slow KAMA Length", minval=2)
signalLen = input.int(9, "Signal KAMA Length", minval=1)

fastSCPeriod = input.int(2, "KAMA Fast SC period", minval=1)
slowSCPeriod = input.int(30, "KAMA Slow SC period", minval=2)

// === Helper: Kaufman's Adaptive Moving Average ===
// src = source series
// n = efficiency lookback length
// fastP, slowP = periods for smoothing constant (SC)
f_kama(src, n, fastP, slowP) =>
var float kama = na
if bar_index == 0
kama := src
else
change = math.abs(src - src[n])
vol = 0.0
for i = 0 to n - 1
vol += math.abs(src - src[i+1])
er = vol == 0.0 ? 0.0 : change / vol
fastSC = 2.0 / (fastP + 1.0)
slowSC = 2.0 / (slowP + 1.0)
sc = math.pow(er * (fastSC - slowSC) + slowSC, 2)
kama := nz(kama[1], src) + sc * (src - nz(kama[1], src))
kama

// === Compute KAMA-based MACD ===
kamaFast = f_kama(close, fastLen, fastSCPeriod, slowSCPeriod)
kamaSlow = f_kama(close, slowLen, fastSCPeriod, slowSCPeriod)
macd_line = kamaFast - kamaSlow
signalKama = f_kama(macd_line, signalLen, fastSCPeriod, slowSCPeriod)
hist = macd_line - signalKama

// === Raw Signals ===
buyRaw = ta.crossover(macd_line, signalKama) and hist > 0
sellRaw = ta.crossunder(macd_line, signalKama) and hist < 0

// === Alternating filter ===
var int lastSignal = 0 // 1 = last Buy, -1 = last Sell, 0 = none
buySignal = buyRaw and lastSignal != 1
sellSignal = sellRaw and lastSignal != -1

if buySignal
lastSignal := 1
if sellSignal
lastSignal := -1

// === Plot Triangles ===
plotshape(buySignal, title="Buy Signal", style=shape.triangleup, location=location.belowbar, color=color.green, size=size.large, text="BUY")
plotshape(sellSignal, title="Sell Signal", style=shape.triangledown, location=location.abovebar, color=color.red, size=size.large, text="SELL")