Zen ATH Bands

//@version=5
indicator("Zen ATH Bands v2.0", overlay=true)

// ============================================================================
//  Zen ATH Bands v2.0 · 20260424
//  Plots the all-time high (ATH) and a configurable ladder of percentage
//  pullback levels below it. Seven independently-toggleable levels with
//  customisable % offsets and colours. Useful for cash indices and other
//  instruments where ATH and its higher-timeframe pullback zones matter.
//
//  Reference write-up:
//  https://zentradingtech.com/2025/12/19/cash-indices-and-higher-time-frame-pullbacks/
// ============================================================================

// -------- Inputs --------
refMode    = input.int(1, "Reference (0=Last price, 1=ATH)", minval=0, maxval=1)
offsetBars = input.int(30, "Right offset (bars)", minval=5, maxval=200)

// --- Level Percentages ---
showATH = input.bool(true, "Show ATH line", group="Level 0")
clrATH  = input.color(color.teal, "ATH Color", group="Level 0")

show1   = input.bool(true, "Show Level 1", group="Level 1")
p1      = input.float(2.5, "Level 1 % Down", minval=0, step=0.5, group="Level 1")
clr1    = input.color(color.green, "Color 1", group="Level 1")

show2   = input.bool(true, "Show Level 2", group="Level 2")
p2      = input.float(5.0, "Level 2 % Down", minval=0, step=0.5, group="Level 2")
clr2    = input.color(color.lime, "Color 2", group="Level 2")

show3   = input.bool(true, "Show Level 3", group="Level 3")
p3      = input.float(10.0, "Level 3 % Down", minval=0, step=0.5, group="Level 3")
clr3    = input.color(color.orange, "Color 3", group="Level 3")

show4   = input.bool(true, "Show Level 4", group="Level 4")
p4      = input.float(15.0, "Level 4 % Down", minval=0, step=0.5, group="Level 4")
clr4    = input.color(color.red, "Color 4", group="Level 4")

show5   = input.bool(true, "Show Level 5", group="Level 5")
p5      = input.float(20.0, "Level 5 % Down", minval=0, step=0.5, group="Level 5")
clr5    = input.color(color.maroon, "Color 5", group="Level 5")

show6   = input.bool(true, "Show Level 6", group="Level 6")
p6      = input.float(25.0, "Level 6 % Down", minval=0, step=0.5, group="Level 6")
clr6    = input.color(color.purple, "Color 6", group="Level 6")

show7   = input.bool(true, "Show Level 7", group="Level 7")
p7      = input.float(30.0, "Level 7 % Down", minval=0, step=0.5, group="Level 7")
clr7    = input.color(color.gray, "Color 7", group="Level 7")

// -------- Exact ATH Calculation --------
var float ath = na
ath := na(ath[1]) ? high : math.max(ath[1], high)

// Reference Selection
ref = refMode == 0 ? close : ath

// -------- Helper Function --------
f_line_and_label(_cond, _perc, _clr) =>
    if _cond
        float _lvl = ref * (1 - (_perc / 100))
        string _txt = str.tostring(_perc) + "%"
        line.new(bar_index, _lvl, bar_index + 1, _lvl, extend=extend.right, color=_clr, width=2)
        label.new(bar_index + offsetBars, _lvl, _txt + " (" + str.tostring(_lvl, format.mintick) + ")",
             textcolor=color.white, style=label.style_label_right, color=_clr)

// -------- Execution (Draw once on the last bar) --------
if barstate.islastconfirmedhistory
    // Handle ATH separately as it's 0% offset
    if showATH
        line.new(bar_index, ref, bar_index + 1, ref, extend=extend.right, color=clrATH, width=2)
        label.new(bar_index + offsetBars, ref, "ATH (" + str.tostring(ref, format.mintick) + ")",
             textcolor=color.white, style=label.style_label_right, color=clrATH)

    // Handle Custom Levels
    f_line_and_label(show1, p1, clr1)
    f_line_and_label(show2, p2, clr2)
    f_line_and_label(show3, p3, clr3)
    f_line_and_label(show4, p4, clr4)
    f_line_and_label(show5, p5, clr5)
    f_line_and_label(show6, p6, clr6)
    f_line_and_label(show7, p7, clr7)