//@version=3
study(title = "Donchian Channel Alerts R1 by JustUncleL", shorttitle="DONALERT", overlay=true)
//
// Author: JustUncleL
//
// Description:
//    This idea is based on the Donchain Channel centre line Price action. When price moves from the highest/lowest
//    point, the price will move to the center line first. At this point, the center line acts as dynamic 
//    support/resistance and often price will bounce back up. However, if price successfully breaks the center line, 
//    primary entry condition, then prices will tend to catch up to the bottom channel line and even make further 
//    moves in that direction, secondary entry condition. 
//
//    This script idea is designed to be used with Renko (10pip brick recommended) Renko or 
//    Heikin Ashi (1 hour recommended) charts. It combines the price action with a directional 
//    coloured EMA (default length 8) and a Donchian Channel to provide entry and exit signals.
//
//    There are three options to exit trade:
//    - MA Cross (default exit) = exit occur when price breaks EMA in opposite direction. 
//    - Centre Cross = exit occurs when price breaks back passed the centre line in opposite direction.
//    - Brick Colour = exit when a brick/bar paints in the opposite colour to trade direction.
//
//    Each Entry and Exit signal creates an Alertcondition that can be picked up by the TradingView Alarm system.
//
//    TIP: Remember this type of Trading technique only works well in a trending market. Do not try to trade
//         this technique in a ranging/flat market.
//
//    TIP: To get 10pip Bricks set Renko to "Traditional" type bricks and 0.001 for non-JPY currency pairs, and
//         0.1 for JPY currency pairs. Also set chart Time frame to 5min or 15mins.
//
// References:
//    - CM_Donchian Channels V3 revised by JustUncleL
//
// Modifications:
//    R1   15-Sep-2017 Original
//

// === INPUTS

// MA - type, source, length
ma_type   = input(defval="EMA", title="MA Type: ", options=["SMA", "EMA", "WMA", "VWMA", "SMMA", "DEMA", "TEMA", "HullMA", "ZEMA", "TMA", "SSMA"])
ma_len    = input(defval=8, title="MA - Length", minval=1)
ma_src    = input(close, title="MA - Source")
//
donlength = input(30, minval=1, title="Donchian Channel Lookback Length")
exitcond  = input("Cross MA",title="Exit Trade when Price ", options=["Cross MA", "Cross Centre", "Brick Colour"])

//
// === /INPUTS

//
// === FUNCTIONS

// - variant(type, src, len)
// Returns MA input selection variant, default to SMA if blank or typo.

// SuperSmoother filter
// © 2013  John F. Ehlers
variant_supersmoother(src,len) =>
    a1 = exp(-1.414*3.14159 / len)
    b1 = 2*a1*cos(1.414*3.14159 / len)
    c2 = b1
    c3 = (-a1)*a1
    c1 = 1 - c2 - c3
    v9 = 0.0
    v9 := c1*(src + nz(src[1])) / 2 + c2*nz(v9[1]) + c3*nz(v9[2])
    v9
    
variant_smoothed(src,len) =>
    v5 = 0.0
    v5 := na(v5[1]) ? sma(src, len) : (v5[1] * (len - 1) + src) / len
    v5

variant_zerolagema(src,len) =>
    ema1 = ema(src, len)
    ema2 = ema(ema1, len)
    v10 = ema1+(ema1-ema2)
    v10
    
variant_doubleema(src,len) =>
    v2 = ema(src, len)
    v6 = 2 * v2 - ema(v2, len)
    v6

variant_tripleema(src,len) =>
    v2 = ema(src, len)
    v7 = 3 * (v2 - ema(v2, len)) + ema(ema(v2, len), len)               // Triple Exponential
    v7
    
// return variant, defaults to SMA 
variant(type, src, len) =>
    type=="EMA"     ? ema(src,len) : 
      type=="WMA"   ? wma(src,len): 
      type=="VWMA"  ? vwma(src,len) : 
      type=="SMMA"  ? variant_smoothed(src,len) : 
      type=="DEMA"  ? variant_doubleema(src,len): 
      type=="TEMA"  ? variant_tripleema(src,len): 
      type=="HullMA"? wma(2 * wma(src, len / 2) - wma(src, len), round(sqrt(len))) :
      type=="SSMA"  ? variant_supersmoother(src,len) : 
      type=="ZEMA"  ? variant_zerolagema(src,len) : 
      type=="TMA"   ? sma(sma(src,len),len) : sma(src,len)

// - /variant 
// === /FUNCTIONS


dodgerblue = #1E90FF

// === Moving Average
ma_series = variant(ma_type,ma_src,ma_len)

// Get direction based on MA
direction = 0
direction := rising(ma_series,3) ? 1 : falling(ma_series,3) ? -1 : nz(direction[1])

// Plot MA series and color it according too direction
pcol = direction>0 ? lime : direction<0 ? red : na
plot(ma_series, title="MA Plot", color=pcol, linewidth=2,style=line,join=true, transp=10)

// === /Moving Average 


// === Donchian Channel
upper = highest(donlength)
lower = lowest(donlength)
basis = avg(upper, lower)

break_Above = high > upper[1]?1:0
break_Below = low < lower[1]?1:0

break_Above_B = close > basis[1]?1:0
break_Below_B = close < basis[1]?1:0

// Plot channel
u = plot(upper, title="Upper DC Band", style=line, linewidth=1, color=blue,offset=0)
l = plot(lower, title="Lower DC Band", style=line, linewidth=1, color=blue,offset=0)
plot(basis, title="Mid-Line", color=orange, style=line, linewidth=2, offset=0)
fill(u, l, color=blue, transp=95, title="Fill")

//
higherhigh = 0
higherhigh := break_Above ? nz(higherhigh[1])>0?higherhigh[1]+1:1 : 0

// Count the lower breaks.
lowerlow = 0
lowerlow :=   break_Below ? nz(lowerlow[1])>0?lowerlow[1]+1:1 : 0


//plotshape(ShowHHLL ? higherhigh : na, title='HH', style=shape.square, location=location.abovebar, color=black, text="HH", offset=0,transp=0)
//plotshape(ShowHHLL ? lowerlow : na, title='LL', style=shape.square, location=location.belowbar, color=black, text="LL", offset=0,transp=0)


// === /Donchian Channel

// === Calculate Alerts

// Entry conditions
PA = (close>open) and ((break_Above_B==1 and (break_Above_B[1]==0 or break_Above_B[2]==0)) or (higherhigh>1))? 1 : 
     (close<open) and ((break_Below_B==1 and (break_Below_B[1]==0 or break_Below_B[2]==0)) or (lowerlow>1))? -1 : 0 
MA = close>ma_series? 1 : close<ma_series? -1 : 0

long  = PA==1 and MA ==1 //and ma_series>=basis
short = PA==-1 and MA ==-1 //and ma_series<=basis

// Exit conditions
exitlong = exitcond=="Cross MA"? MA<0 ? 1 : MA>0 ? 0 : 0 :
           exitcond=="Cross Centre"? break_Below_B ? 1 : 0 :
           exitcond=="Brick Colour"? (close<open and close[1]>open[1]) ? 1 : 0 : 0
           
exitshort= exitcond=="Cross MA"? MA>0 ? 1 : MA<0 ? 0 : 0 :
           exitcond=="Cross Centre"? break_Above_B ? 1 : 0 :
           exitcond=="Brick Colour"? (close>open and close[1]<open[1]) ? 1 : 0 : 0
           
// Alert State
olong = 0
olong := nz(olong[1])>0?  exitlong==1? 0 : olong[1]+1 : long? 1 : 0
oshort = 0
oshort := nz(oshort[1])>0? exitshort==1? 0 : oshort[1]+1 : short? 1 : 0

// - Plot Alerts
plotarrow(olong==1?1:na, title="BUY Arrow", colorup=lime, maxheight=60, minheight=50, transp=20,offset=0)
plotarrow(oshort==1?-1:na, title="SELL Arrow", colordown=red, maxheight=60, minheight=50, transp=20,offset=0)
//
plotshape(olong[1]>0 and olong==0, title='BUY Exit', style=shape.xcross, location=location.belowbar, color=gray, text="Exit\nBuy", offset=0,transp=0)
plotshape(oshort[1]>0 and oshort==0, title='Sell Exit', style=shape.xcross, location=location.abovebar, color=gray, text="Exit\nSell", offset=0,transp=0)

// - Signal Alerts to TV Alarm system
alertcondition(olong==1,title="Break BUY Alert",message="BUY")
alertcondition(oshort==1,title="Break SELL Alert",message="SELL")
alertcondition(olong[1]>0 and olong==0,title="Break BUY Exit Alert",message="BUY Exit")
alertcondition(oshort[1]>0 and oshort==0,title="Break SELL Exit Alert",message="SELL Exit")

// === /Calculate Alerts


// --- debugs
//plotshape(higherhigh,location=location.bottom)
//plotshape(lowerlow,location=location.bottom)
//plotshape(break_Above_B,location=location.bottom)
//plotshape(break_Below_B,location=location.bottom)
//plotshape(PA,location=location.bottom)
//plotshape(MA,location=location.bottom)
//plotshape(olong,location=location.bottom)
//plotshape(oshort,location=location.bottom)
// --- /debugs

//EOF