-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=605

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-- Indicator profile initialization routine
-- Defines indicator profile properties and indicator parameters
function Init()
    indicator:name("SuperTrend Overlay");
    indicator:description("The indicator displays the buying and selling with the colors. The indicator is initially developed by Jason Robinson for MT4");
    indicator:requiredSource(core.Bar);
    indicator:type(core.Indicator);

	indicator.parameters:addGroup("Calculation");
    indicator.parameters:addInteger("N", "Number of periods", "No description", 10);
    indicator.parameters:addDouble("M", "Multiplier", "No description", 1.5);
	indicator.parameters:addGroup("Style");
    indicator.parameters:addColor("Up", "Color of Up", " ", core.rgb(0, 255, 0));
    indicator.parameters:addColor("Down", "Color of Down", " ", core.rgb(255, 0, 0));
	indicator.parameters:addColor("Neutral", "Color of Neutral", " ", core.rgb(128,128, 128));

end

-- Indicator instance initialization routine
-- Processes indicator parameters and creates output streams
-- Parameters block
local N;
local M;

local first;
local source = nil;
local ATR = nil;

-- Streams block

local UP = nil;
local DN = nil;
local TR = nil;

local  open=nil;
local  close=nil;
local  high=nil;
local  low=nil;

local Up,Down,Neutral;

-- Routine
 function Prepare(nameOnly)   
    N = instance.parameters.N;
    M = instance.parameters.M;
    source = instance.source;
  
    local name = profile:id() .. "(" .. source:name() .. ", " .. N .. ", " .. M .. ")";
    instance:name(name);
	
	if   (nameOnly) then
        return;
    end
	
	Up = instance.parameters.Up;
	Down = instance.parameters.Down;
	Neutral = instance.parameters.Neutral;
	
	ATR = core.indicators:create("ATR", source, N);
    first = ATR.DATA:first();
	
    UP = instance:addInternalStream(first, 0);
    DN = instance:addInternalStream(first, 0);
    TR = instance:addInternalStream(first, 0);
	
	open = instance:addStream("openup", core.Line, name, "", core.rgb(0, 0, 0), first);
    high = instance:addStream("highup", core.Line, name, "", core.rgb(0, 0, 0), first);
    low = instance:addStream("lowup", core.Line, name, "", core.rgb(0, 0, 0), first);
    close = instance:addStream("closeup", core.Line, name, "", core.rgb(0, 0, 0), first);
    instance:createCandleGroup("OVERLAY", "OVERLAY", open, high, low, close);
  
end

-- Indicator calculation routine
function Update(period, mode)


    open[period] = source.open[period];
	close[period] = source.close[period];
	high[period] = source.high[period];
	low[period] = source.low[period];
	
    ATR:update(mode);
    TR[period] = 1;
	
    if period < first then
	open:setColor(period, Neutral);	
	return;
	end
	
        local median, atr, change;
        atr = ATR.DATA[period];
        median = (source.high[period] + source.low[period]) / 2;
        UP[period] = median + atr * M;
        DN[period] = median - atr * M;

        if period >= first + 1 then
            change = false;
            if source.close[period] > UP[period - 1] then
                TR[period] = 1;
                if TR[period - 1] == -1 then
                    change = true;
                end
            elseif source.close[period] < DN[period - 1] then
                TR[period] = -1;
                if TR[period - 1] == 1 then
                    change = true;
                end
            else
                TR[period] = TR[period - 1];
            end

            local flag, flagh;

            if TR[period] < 0 and TR[period - 1] > 0 then
               flag = 1;
            else
               flag = 0;
            end

            if TR[period] > 0 and TR[period - 1] < 0 then
               flagh = 1;
            else
               flagh = 0;
            end

            if TR[period] > 0 and DN[period] < DN[period - 1] then
                DN[period] = DN[period - 1];
            end

            if TR[period] < 0 and UP[period] > UP[period - 1] then
                UP[period] = UP[period - 1];
            end

            if flag == 1 then
                UP[period] = median + atr * M;
            end

            if flagh == 1 then
                DN[period] = median - atr * M;
            end

            
        end
		
		
		if TR[period] > 0 then		
		open:setColor(period,  Up);
        elseif TR[period] < 0 then
		open:setColor(period,  Down);
		else
		open:setColor(period, Neutral);			
		end
   
end