study("xabcde", overlay=true)
useAltTF = input(true, title='Use Alt Timeframe')
tf = input('15', title='Alt Timeframe')
showPatterns = input(true, title='Show Patterns')
zigzag() =>
    _isUp = close >= open
    _isDown = close <= open
    _direction = _isUp[1] and _isDown ? -1 : _isDown[1] and _isUp ? 1 : nz(_direction[1])
    _zigzag = _isUp[1] and _isDown and _direction[1] != -1 ? highest(2) : _isDown[1] and _isUp and _direction[1] != 1 ? lowest(2) : na

sz = useAltTF ? (change(time(tf)) != 0 ? security(tickerid, tf, zigzag()) : na) : zigzag()

plot(sz, title='zigzag', color=black, linewidth=2)

//  ||---   Pattern Recognition:

x = valuewhen(sz, sz, 5)
a = valuewhen(sz, sz, 4)
b = valuewhen(sz, sz, 3)
c = valuewhen(sz, sz, 2)
d = valuewhen(sz, sz, 1)
e = valuewhen(sz, sz, 0)

xab = (abs(b-a)/abs(x-a))
xad = (abs(a-d)/abs(x-a))
abc = (abs(b-c)/abs(a-b))
bcd = (abs(c-d)/abs(b-c))
cde = (abs(d-e)/abs(c-d))

//  ||-->   Functions:

isHnS(_mode)=>
    _xab = xab >= 2.0 and xab <= 10
    _abc = abc >= 0.90 and abc <= 1.1
    _bcd = bcd >= 0.236 and bcd <= 0.88
    _xad = xad >= 0.90 and xad <= 1.1
    _xab and _abc and _bcd and _xad and (_mode == 1 ? d < c : d > c)


plotshape(not showPatterns ? na : isHnS(-1) and not isHnS(-1)[1], text="Head and Shoulders", style=shape.labeldown, color=maroon, textcolor=white, location=location.top, transp=0)
plotshape(not showPatterns ? na : isHnS(1) and not isHnS(1)[1], text="Head and Shoulders", style=shape.labelup, color=green, textcolor=white, location=location.bottom, transp=0)