//@version=5
indicator("Stochastic with Buy/Sell Signals", overlay=true)

// パラメータ設定
kLength   = input.int(14, title="K期間")
dLength   = input.int(3, title="D期間")
smoothK   = input.int(3, title="スムージング期間")

// 計算
k = ta.sma(ta.stoch(close, high, low, kLength), smoothK)
d = ta.sma(k, dLength)

// オシレーター表示
plot(k, title="%K", color=color.blue)
plot(d, title="%D", color=color.orange)
hline(80, "Overbought", color=color.red)
hline(20, "Oversold", color=color.green)

// シグナル条件
buySignal  = ta.crossover(k, d) and k < 20
sellSignal = ta.crossunder(k, d) and k > 80

// チャートにシグナル表示
plotshape(buySignal,  title="Buy Signal",  style=shape.triangleup,   location=location.belowbar, color=color.green, size=size.small, text="BUY")
plotshape(sellSignal, title="Sell Signal", style=shape.triangledown, location=location.abovebar, color=color.red,   size=size.small, text="SELL")