Bài 6 — Pivot high + trendline trên chart (tránh lỗi valuewhen)

strategy "Pivot TL Demo"
    @regime     "trending"
    @style      "breakout, swing"
    @detail "Trendline từ swing high đã xác nhận; thoát khi chạm peak gần nhất."

params:
  pivot_lookback = 5 in [3..12]
  exit_lookback = 20 in [10..60]

detect:
  c = market.close
  h = market.high
  ph = swinghigh(h, pivot_lookback, pivot_lookback)
  ph_h = valuewhen(ph, h)
  ph_t = valuewhen(ph, bar.time)
  ph_i = valuewhen(ph, bar.index)
  p1_h = valuewhen(ph, ph_h[1])
  p1_t = valuewhen(ph, ph_t[1])
  p1_i = valuewhen(ph, ph_i[1])
  p2_h = ph_h
  p2_t = ph_t
  p2_i = ph_i
  slope = safediv(p2_h - p1_h, p2_i - p1_i, 0.0)
  current_tl = p2_h + slope * (bar.index - p2_i)
  peak_exit = hhv(h, exit_lookback)
  buy_sig = c crossover current_tl
  sell_sig = h crossover peak_exit[1]

act:
  when buy_sig and not position.is_long:
    enter long with wnav 5pct tag "tl breakout"
  when sell_sig and position.is_long:
    close long tag "peak touch"

render:
  panel main:
    line peak_exit as "Recent peak" in orange dashed
    trendline [p1_t, p1_h] to [p2_t, p2_h] in yellow with width 2 with extend right limit by 5
    mark buy_sig as "Long" at below_bar in lime shaped arrow_up
    mark sell_sig as "Exit" at above_bar in red shaped arrow_down