//@version=3

study(title="[ALERTS] Range Filter", overlay=true)

// Source

src = input(defval=close, title="Source")

// Sampling Period

per = input(defval=14, minval=1, title="Sampling Period")

// Range Multiplier

mult = input(defval=2.618, minval=0, title="Range Multiplier")

// Smooth Average Range

smoothrng(x, t, m)=>
    wper      = (t*2) - 1
    avrng     = ema(abs(x - x[1]), t)
    smoothrng = ema(avrng, wper)*m
    smoothrng
smrng = smoothrng(src, per, mult)

// Range Filter

rngfilt(x, r)=>
    rngfilt  = x
    rngfilt := x > nz(rngfilt[1]) ? ((x - r) < nz(rngfilt[1]) ? nz(rngfilt[1]) : (x - r)) : ((x + r) > nz(rngfilt[1]) ? nz(rngfilt[1]) : (x + r))
    rngfilt
filt = rngfilt(src, smrng)

// Filter Direction

upward   = 0.0
upward  := filt > filt[1] ? nz(upward[1]) + 1 : filt < filt[1] ? 0 : nz(upward[1])
downward = 0.0
downward := filt < filt[1] ? nz(downward[1]) + 1 : filt > filt[1] ? 0 : nz(downward[1])

// Target Bands

hband = filt + smrng
lband = filt - smrng

// Colors

filtcolor = upward > 0 ? lime : downward > 0 ? red : orange
barcolor  = (src > filt) and (src > src[1]) and (upward > 0) ? lime : (src > filt) and (src < src[1]) and (upward > 0) ? green : 
   (src < filt) and (src < src[1]) and (downward > 0) ? red : (src < filt) and (src > src[1]) and (downward > 0) ? maroon : orange

filtplot = plot(filt, color=filtcolor, linewidth=3, title="Range Filter")

// Target

hbandplot = plot(hband, color=aqua, transp=100, title="High Target")
lbandplot = plot(lband, color=fuchsia, transp=100, title="Low Target")

// Fills

fill(hbandplot, filtplot, color=aqua, title="High Target Range")
fill(lbandplot, filtplot, color=fuchsia, title="Low Target Range")

// Bar Color

barcolor(barcolor)

// Strategy

longCond = na
shortCond = na
longCond := ((src > filt) and (src > src[1]) and (upward > 0)) or ((src > filt) and (src < src[1]) and (upward > 0)) 
shortCond := ((src < filt) and (src < src[1]) and (downward > 0)) or ((src < filt) and (src > src[1]) and (downward > 0))

CondIni = 0
CondIni := longCond ? 1 : shortCond ? -1 : CondIni[1]
longCondition = longCond and CondIni[1] == -1
shortCondition = shortCond and CondIni[1] == 1

// Alerts & Signals

plotshape(longCondition, title = "Buy Signal", text ="BUY", textcolor = green, style=shape.triangleup, location=location.belowbar, color = lime, transp = 0, size = size.tiny)
plotshape(shortCondition, title = "Sell Signal", text ="SELL", textcolor = maroon, style=shape.triangledown, location=location.abovebar, color = red, transp = 0, size = size.tiny)

alertcondition((longCondition or shortCondition), title="Buy/Sell Alert", message = "BUY/SELL")

alertcondition(longCondition, title="Buy Alert", message = "BUY")

alertcondition(shortCondition, title="Sell Alert", message = "SELL")