ATR Breakout Channel [QuantForge]

//@version=6
strategy("ATR Breakout Channel [QuantForge]",
     overlay = true,
     initial_capital = 10000,
     default_qty_type = strategy.percent_of_equity,
     default_qty_value = 10,
     commission_type = strategy.commission.percent,
     commission_value = 0.05,
     slippage = 2)

// ============================================================
// ATR Breakout Channel - QuantForge portfolio demo
// Trend-following engine:
// Entry: close breaks the prior N-bar extreme (confirmed bar),
//        in the direction of the long-term EMA trend.
// Exit:  ratcheting ATR trailing stop (chandelier style).
//        Initial stop frozen at entry, then trails, never loosens.
// No repainting: channel uses prior-bar extremes only.
// ============================================================

// ---------- Inputs ----------
donLen      = input.int(20,  "Breakout channel length", minval = 5, group = "Entry")
tradeDir    = input.string("Both", "Trade direction", options = ["Long only", "Short only", "Both"], group = "Entry")
useTrend    = input.bool(true, "Use EMA trend filter", group = "Entry")
emaLen      = input.int(200, "Trend EMA length", minval = 10, group = "Entry")
atrLen      = input.int(14,  "ATR length", minval = 1, group = "Risk")
trailMult   = input.float(3.0, "Trailing stop (ATR mult)", step = 0.25, minval = 0.5, group = "Risk")
startDate   = input.time(timestamp("1 Jan 2023 00:00 +0000"), "Start date", group = "Test window")
endDate     = input.time(timestamp("1 Jan 2030 00:00 +0000"), "End date",   group = "Test window")

// ---------- Channel and filters ----------
chanHigh = ta.highest(high, donLen)[1]
chanLow  = ta.lowest(low,  donLen)[1]
atrVal   = ta.atr(atrLen)
emaVal   = ta.ema(close, emaLen)

trendLongOK  = not useTrend or close > emaVal
trendShortOK = not useTrend or close < emaVal

inWindow   = time >= startDate and time <= endDate
allowLong  = tradeDir != "Short only"
allowShort = tradeDir != "Long only"

longSignal  = close > chanHigh and trendLongOK
shortSignal = close < chanLow  and trendShortOK

// ---------- Entries ----------
if longSignal and allowLong and inWindow and strategy.position_size == 0
    strategy.entry("Long", strategy.long)

if shortSignal and allowShort and inWindow and strategy.position_size == 0
    strategy.entry("Short", strategy.short)

// ---------- Ratcheting ATR trailing stop ----------
var float trailStop = na

if strategy.position_size > 0
    candidate = close - trailMult * atrVal
    trailStop := na(trailStop) ? candidate : math.max(trailStop, candidate)
    strategy.exit("Long trail", from_entry = "Long", stop = trailStop)
else if strategy.position_size < 0
    candidate = close + trailMult * atrVal
    trailStop := na(trailStop) ? candidate : math.min(trailStop, candidate)
    strategy.exit("Short trail", from_entry = "Short", stop = trailStop)
else
    trailStop := na

// ---------- Visuals ----------
pH = plot(chanHigh, "Channel high", color = color.new(color.teal, 30))
pL = plot(chanLow,  "Channel low",  color = color.new(color.teal, 30))
fill(pH, pL, color = color.new(color.teal, 92), title = "Channel")
plot(emaVal, "Trend EMA", color = color.new(color.purple, 50))
plot(strategy.position_size != 0 ? trailStop : na, "Trailing stop",
     color = color.new(color.red, 0), style = plot.style_linebr, linewidth = 2)

// ---------- Alerts ----------
alertcondition(longSignal,  "Long breakout",  "Close broke above the N-bar channel high with trend filter passed")
alertcondition(shortSignal, "Short breakout", "Close broke below the N-bar channel low with trend filter passed")