Trend Lines v2

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

//@version=4
study("Trend Lines v2", overlay=true, max_bars_back = 4000)
startyear = input(defval = 2020, title = "Start Year")
startmonth = input(defval = 1, title = "Start Month")
startday = input(defval = 1, title = "Start day")
tlprd = input(defval = 20, title="Pivot Period", minval = 10, maxval = 50)
PPnum = input(defval = 3, title="Number of Pivot Points to check", minval = 2, maxval = 6)
utcol = input(defval = color.lime, title = "Colors", inline = "tcol")
dtcol = input(defval = color.red, title = "", inline = "tcol")

float tlph = pivothigh(tlprd, tlprd)
float tlpl = pivotlow(tlprd, tlprd)

var tval = array.new_float(PPnum)
var tpos = array.new_int(PPnum)
var bval = array.new_float(PPnum)
var bpos = array.new_int(PPnum)

add_to_array(apointer1, apointer2, val)=>
    array.unshift(apointer1, val)
    array.unshift(apointer2, bar_index)
    array.pop(apointer1)
    array.pop(apointer2)

if tlph
    add_to_array(tval, tpos, tlph)

if tlpl
    add_to_array(bval, bpos, tlpl)
    
// line definitions
maxline = 3
var bln = array.new_line(maxline, na)
var tln = array.new_line(maxline, na)

// loop for pivot points to check if there is possible trend line
countlinelo = 0
countlinehi = 0

starttime = timestamp(startyear, startmonth, startday, 0, 0, 0)

if time >= starttime
    for x = 0 to maxline - 1
        line.delete(array.get(bln, x))
        line.delete(array.get(tln, x))
    for p1 = 0 to PPnum - 2 
        uv1 = 0.0
        uv2 = 0.0
        up1 = 0
        up2 = 0
        if countlinelo <= maxline
            for p2 = PPnum - 1 to p1 + 1
                val1 = array.get(bval, p1)
                val2 = array.get(bval, p2)
                pos1 = array.get(bpos, p1)
                pos2 = array.get(bpos, p2)
                if val1 > val2
                    diff = (val1 - val2) / (pos1 - pos2)
                    hline = val2 + diff
                    lloc = bar_index
                    lval = low
                    valid = true
                    for x = pos2 + 1 - tlprd to bar_index
                        if close[bar_index - x] < hline
                            valid := false
                            break
                        lloc := x
                        lval := hline
                        hline := hline + diff
                    
                        
                    if valid
                        uv1 := hline - diff
                        uv2 := val2
                        up1 := lloc
                        up2 := pos2
                        break

        dv1 = 0.0
        dv2 = 0.0
        dp1 = 0
        dp2 = 0                
        if countlinehi <= maxline
            for p2 = PPnum - 1 to p1 + 1                
                val1 = array.get(tval, p1)
                val2 = array.get(tval, p2)
                pos1 = array.get(tpos, p1)
                pos2 = array.get(tpos, p2)
                if val1 < val2
                    diff = (val2 - val1) / float(pos1 - pos2)
                    hline = val2 - diff
                    lloc = bar_index
                    lval = high
                    valid = true
                    for x = pos2 + 1 - tlprd to bar_index
                        if close[bar_index - x] > hline
                            valid := false
                            break
                        lloc := x
                        lval := hline
                        hline := hline - diff
                        
                    if valid
                        dv1 := hline + diff
                        dv2 := val2
                        dp1 := lloc
                        dp2 := pos2
                        break
                         
        // if there is continues uptrend line then draw it
        if up1 != 0 and up2 != 0 and countlinelo < maxline
            countlinelo += 1
            array.set(bln, countlinelo - 1, line.new(up2 - tlprd, uv2, up1, uv1, color = utcol))
        
        // if there is continues downtrend line then draw it
        if dp1 != 0 and dp2 != 0 and countlinehi < maxline
            countlinehi += 1
            array.set(tln, countlinehi - 1, line.new(dp2 - tlprd, dv2, dp1, dv1, color = dtcol))