Support Resistance MTF

// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © LonesomeTheBlue

//@version=5
indicator('Support Resistance MTF', overlay=true, max_bars_back=4900)
src = input.string(defval='High/Low', title='Source', options=['High/Low', 'Close/Open'])
TimeframeU = input.string(defval='Auto', title='Higher Time Frame', options=['Auto', '15', '30', '60', '120', '180', '240', '720', 'D', 'W', '2W', 'M', '3M', '6M', '12M'])
prd = input.int(defval=10, title='Period for Highest/Lowest Bars', minval=1)
resistancecol = input(defval=color.red, title='Resistance Color')
supportcol = input(defval=color.lime, title='Support Color')
Transp = input.int(defval=80, title='Transparency for Zones', minval=0, maxval=100)
extendlines = input(defval=false, title='Extend Lines')

Timeframe = timeframe.period
if TimeframeU == 'Auto'
    Timeframe := timeframe.period == '1' ? '15' : timeframe.period == '3' ? '15' : timeframe.period == '5' ? '60' : timeframe.period == '15' ? '60' : timeframe.period == '30' ? '120' : timeframe.period == '45' ? '120' : timeframe.period == '60' ? '240' : timeframe.period == '120' ? 'D' : timeframe.period == '180' ? 'D' : timeframe.period == '240' ? 'D' : timeframe.period == 'D' ? 'W' : timeframe.period == 'W' ? 'M' : '12M'
    Timeframe
else
    Timeframe := TimeframeU
    Timeframe

var float hc = na
var float lc = na
srch = src == 'High/Low' ? high : math.max(close, open)
srcl = src == 'High/Low' ? low : math.min(close, open)
hc := ta.highestbars(srch, prd) == 0 ? srch : hc
lc := ta.lowestbars(srcl, prd) == 0 ? srcl : lc

hcp = plot(hc, color=hc == hc[1] ? resistancecol : na)
lcp = plot(lc, color=lc == lc[1] ? supportcol : na)

bool newbar = ta.change(time(Timeframe)) != 0
var float htfh = na
var float htfl = na
if newbar
    htfh := srch
    htfl := srcl
    htfl
else
    htfh := math.max(htfh, srch)
    htfl := math.min(htfl, srcl)
    htfl

highestbar(src, len) =>
    ll = 1
    if len > 1
        for x = 0 to 4000 by 1
            if na(newbar[x]) or na(close[x + 1])
                break
            if newbar[x]
                if src <= src[x + 1]
                    break
                ll += 1
                if ll >= len
                    break
    ret = ll >= len
    ret

lowestbar(src, len) =>
    ll = 1
    if len > 1
        for x = 0 to 4000 by 1
            if na(newbar[x]) or na(close[x + 1])
                break
            if newbar[x]
                if src >= src[x + 1]
                    break
                ll += 1
                if ll >= len
                    break
    ret = ll >= len
    ret

var float hh = 0
var float ll = 0
bool hbar = highestbar(htfh, prd)
bool lbar = lowestbar(htfl, prd)
hh := hbar ? htfh : hh
ll := lbar ? htfl : ll

hhp = plot(hh, color=hh == hh[1] ? resistancecol : na)
llp = plot(ll, color=ll == ll[1] ? supportcol : na)

fill(hhp, hcp, color=hc == hc[1] and hh == hh[1] ? color.new(resistancecol, Transp) : na, transp=90)
fill(llp, lcp, color=lc == lc[1] and ll == ll[1] ? color.new(supportcol, Transp) : na, transp=90)

// extend lines
if extendlines
    var line s1 = na
    var line s2 = na
    var line r1 = na
    var line r2 = na
    line.delete(s1)
    line.delete(s2)
    line.delete(r1)
    line.delete(r2)
    s1 := line.new(bar_index, lc, bar_index - 1, lc, color=supportcol, extend=extend.left)
    s2 := line.new(bar_index, ll, bar_index - 1, ll, color=supportcol, extend=extend.left)
    r1 := line.new(bar_index, hc, bar_index - 1, hc, color=resistancecol, extend=extend.left)
    r2 := line.new(bar_index, hh, bar_index - 1, hh, color=resistancecol, extend=extend.left)
    r2