PineForge Heliograph While Channel

//@version=6
// SPDX-License-Identifier: Apache-2.0
// Copyright 2026 PineForge
// PineForge Corporate Strategy: Heliograph While Channel
// A recency-weighted centerline is calculated explicitly with a while loop.
strategy("PineForge — Heliograph While Channel", overlay=true,
     initial_capital=100000,
     default_qty_type=strategy.fixed, default_qty_value=2,
     pyramiding=0, commission_type=strategy.commission.percent,
     commission_value=0.05, slippage=1,
     margin_long=100, margin_short=100,
     process_orders_on_close=false, calc_on_order_fills=false)

channelLength = input.int(28, "Channel Length", minval=5, maxval=120, group="Signal")
bandWidth = input.float(1.25, "Band Width", minval=0.25, step=0.05, group="Signal")
atrLength = input.int(17, "ATR Length", minval=2, group="Risk")
stopAtr = input.float(2.4, "Stop ATR", minval=0.5, step=0.1, group="Risk")
maximumHoldBars = input.int(160, "Maximum Hold Bars", minval=8, group="Risk")

float weightedSum = 0.0
float weightTotal = 0.0
int cursor = 0
while cursor < channelLength
    sample = close[cursor]
    weight = channelLength - cursor
    if not na(sample)
        weightedSum += sample * weight
        weightTotal += weight
    cursor += 1

center = weightTotal > 0 ? weightedSum / weightTotal : na
dispersion = ta.stdev(close, channelLength)
upperBand = center + dispersion * bandWidth
atrValue = ta.atr(atrLength)

var int openedAt = na
if strategy.position_size > 0 and strategy.position_size[1] == 0
    openedAt := bar_index

entrySignal = ta.crossover(close, upperBand)
exitSignal = ta.crossunder(close, center)
holdExpired = strategy.position_size > 0 and not na(openedAt) and bar_index - openedAt >= maximumHoldBars

if entrySignal
    strategy.entry("Heliograph Long", strategy.long)

if strategy.position_size > 0 and (exitSignal or holdExpired)
    strategy.close("Heliograph Long", comment=holdExpired ? "Maximum hold" : "Centerline exit")

if strategy.position_size > 0
    strategy.exit("Heliograph Guard", from_entry="Heliograph Long",
         stop=strategy.position_avg_price - atrValue * stopAtr)

if strategy.position_size == 0
    openedAt := na

plot(center, "Weighted Center", color=color.yellow)
plot(upperBand, "Upper Band", color=color.orange)