Trendlines with Breaks [LuxAlgo]
// This work is licensed under a Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) https://creativecommons.org/licenses/by-nc-sa/4.0/
// © LuxAlgo

//@version=5
indicator("Trendlines with Breaks [LuxAlgo]", "LuxAlgo - Trendlines with Breaks", overlay = true)
//------------------------------------------------------------------------------
//Settings
//-----------------------------------------------------------------------------{
length = input.int(14, 'Swing Detection Lookback')
mult = input.float(1., 'Slope', minval = 0, step = .1)
calcMethod = input.string('Atr', 'Slope Calculation Method', options = ['Atr','Stdev','Linreg'])
backpaint = input(true, tooltip = 'Backpainting offset displayed elements in the past. Disable backpainting to see real time information returned by the indicator.')

//Style
upCss = input.color(color.teal, 'Up Trendline Color', group = 'Style')
dnCss = input.color(color.red, 'Down Trendline Color', group = 'Style')
showExt = input(true, 'Show Extended Lines')

//-----------------------------------------------------------------------------}
//Calculations
//-----------------------------------------------------------------------------{
var upper = 0.
var lower = 0.
var slope_ph = 0.
var slope_pl = 0.

var offset = backpaint ? length : 0

n = bar_index
src = close

ph = ta.pivothigh(length, length)
pl = ta.pivotlow(length, length)

//Slope Calculation Method
slope = switch calcMethod
    'Atr'    => ta.atr(length) / length * mult
    'Stdev'  => ta.stdev(src,length) / length * mult
    'Linreg' => math.abs(ta.sma(src * n, length) - ta.sma(src, length) * ta.sma(n, length)) / ta.variance(n, length) / 2 * mult

//Get slopes and calculate trendlines
slope_ph := ph ? slope : slope_ph
slope_pl := pl ? slope : slope_pl

upper := ph ? ph : upper - slope_ph
lower := pl ? pl : lower + slope_pl

var upos = 0
var dnos = 0
upos := ph ? 0 : close > upper - slope_ph * length ? 1 : upos
dnos := pl ? 0 : close < lower + slope_pl * length ? 1 : dnos

//-----------------------------------------------------------------------------}
//Extended Lines
//-----------------------------------------------------------------------------{
var uptl  = line.new(na,na,na,na, color = upCss, style = line.style_dashed, extend = extend.right)
var dntl  = line.new(na,na,na,na, color = dnCss, style = line.style_dashed, extend = extend.right)

if ph and showExt
    uptl.set_xy1(n-offset, backpaint ? ph : upper - slope_ph * length)
    uptl.set_xy2(n-offset+1, backpaint ? ph - slope : upper - slope_ph * (length+1))

if pl and showExt
    dntl.set_xy1(n-offset, backpaint ? pl : lower + slope_pl * length)
    dntl.set_xy2(n-offset+1, backpaint ? pl + slope : lower + slope_pl * (length+1))

//-----------------------------------------------------------------------------}
//Plots
//-----------------------------------------------------------------------------{
plot(backpaint ? upper : upper - slope_ph * length, 'Upper', color = ph ? na : upCss, offset = -offset)
plot(backpaint ? lower : lower + slope_pl * length, 'Lower', color = pl ? na : dnCss, offset = -offset)

//Breakouts
plotshape(upos > upos[1] ? low : na, "Upper Break"
  , shape.labelup
  , location.absolute
  , upCss
  , text = "B"
  , textcolor = color.white
  , size = size.tiny)

plotshape(dnos > dnos[1] ? high : na, "Lower Break"
  , shape.labeldown
  , location.absolute
  , dnCss
  , text = "B"
  , textcolor = color.white
  , size = size.tiny)

//-----------------------------------------------------------------------------}
//Alerts
//-----------------------------------------------------------------------------{
alertcondition(upos > upos[1], 'Upward Breakout', 'Price broke the down-trendline upward')
alertcondition(dnos > dnos[1], 'Downward Breakout', 'Price broke the up-trendline downward')

//-----------------------------------------------------------------------------}