Linear Regression Channel - Eterna

//@version=5
strategy("Linear Regression Channel - Eterna", 
         overlay=true, 
         initial_capital=10000,
         default_qty_type=strategy.percent_of_equity, 
         default_qty_value=10,
         commission_type=strategy.commission.percent,
         commission_value=0.075)

// ==================== Parameters ====================
lengthLR = input.int(100, "Linear Regression Length", minval=10)
deviationMultiplier = input.float(2.0, "Deviation Multiplier", minval=0.5, step=0.1)
trendEMA = input.int(50, "Trend Filter EMA", minval=1)
leverage = input.int(5, "Leverage", minval=1, maxval=100)
positionSize = input.float(0.01, "Position Size", minval=0.001, step=0.001)

webhookMessage = input.string('{"action":"{{strategy.order.action}}", "symbol":"{{ticker}}", "size":' + str.tostring(positionSize) + ', "leverage":' + str.tostring(leverage) + '}', 
                               "Webhook JSON", group="Webhook")

// ==================== Linear Regression Calculation ====================
linReg = ta.linreg(close, lengthLR, 0)

// Calculate standard deviation for bands
calcDev() =>
    sumDev = 0.0
    for i = 0 to lengthLR - 1
        sumDev := sumDev + math.pow(close[i] - ta.linreg(close, lengthLR, i), 2)
    math.sqrt(sumDev / lengthLR)

dev = calcDev()
upperBand = linReg + (dev * deviationMultiplier)
lowerBand = linReg - (dev * deviationMultiplier)
emaFilter = ta.ema(close, trendEMA)

// ==================== Entry Conditions ====================
// Trend direction based on EMA and linear regression slope
uptrend = close > emaFilter and linReg > linReg[5]
downtrend = close < emaFilter and linReg < linReg[5]

// Long: Price bounces off lower band in uptrend
longBounce = ta.crossover(close, lowerBand) and low <= lowerBand
longCondition = uptrend and longBounce

// Short: Price rejects from upper band in downtrend
shortReject = ta.crossunder(close, upperBand) and high >= upperBand
shortCondition = downtrend and shortReject

// Exit when price crosses back to linear regression line
exitLong = ta.crossunder(close, linReg)
exitShort = ta.crossover(close, linReg)

// ==================== Strategy Execution ====================
if longCondition
    strategy.entry("Long", strategy.long, alert_message=str.replace(webhookMessage, "{{strategy.order.action}}", "buy"))

if shortCondition
    strategy.entry("Short", strategy.short, alert_message=str.replace(webhookMessage, "{{strategy.order.action}}", "sell"))

if exitLong
    strategy.close("Long", alert_message='{"action":"close", "symbol":"{{ticker}}"}')

if exitShort
    strategy.close("Short", alert_message='{"action":"close", "symbol":"{{ticker}}"}')

// ==================== Plotting ====================
linRegPlot = plot(linReg, "Linear Regression", color=color.blue, linewidth=2)
upperPlot = plot(upperBand, "Upper Band", color=color.new(color.green, 0), linewidth=1)
lowerPlot = plot(lowerBand, "Lower Band", color=color.new(color.red, 0), linewidth=1)
plot(emaFilter, "Trend EMA", color=color.orange, linewidth=1)

// Fill channel
fill(upperPlot, lowerPlot, color=color.new(color.blue, 93))

// Entry signals
plotshape(longCondition, "Long", shape.triangleup, location.belowbar, color.green, size=size.normal)
plotshape(shortCondition, "Short", shape.triangledown, location.abovebar, color.red, size=size.normal)

// Show regression slope
slopeUp = linReg > linReg[5]
bgcolor(slopeUp ? color.new(color.green, 96) : color.new(color.red, 96))

// Plot channel slope angle indicator
slopeAngle = math.atan((linReg - linReg[10]) / 10) * (180 / math.pi)
var label slopeLabel = na
if bar_index % 20 == 0
    label.delete(slopeLabel)
    slopeLabel := label.new(bar_index, high, "Slope: " + str.tostring(slopeAngle, "#.#") + "°", 
                            color=slopeAngle > 0 ? color.green : color.red, 
                            textcolor=color.white, size=size.small, style=label.style_label_down)