-- More information about this indicator can be found at:
-- https://fxcodebase.com/code/viewtopic.php?f=17&t=71785

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-- Indicator profile initialization routine
-- Defines indicator profile properties and indicator parameters
-- TODO: Add minimal and maximal value of numeric parameters and default color of the streams
function Init()
    indicator:name("EFT Histo");
    indicator:description("");
    indicator:requiredSource(core.Bar);
    indicator:type(core.Oscillator);

 	 indicator.parameters:addGroup("Calculation");	
    indicator.parameters:addInteger("Period", "Period", "", 30, 1, 2000);	
    indicator.parameters:addDouble("PriceSmooth", "Price smoothing", "", 0.3, 0, 0.9999);		
    indicator.parameters:addDouble("IndexSmooth", "Index smoothing", "", 0.3, 0, 0.9999);		
 
	
	 indicator.parameters:addGroup("Line Style");	
    indicator.parameters:addInteger("width", "Line width", "", 1, 1, 5);
    indicator.parameters:addInteger("style", "Line style", "", core.LINE_SOLID);
    indicator.parameters:setFlag("style", core.FLAG_LINE_STYLE);
	
	 indicator.parameters:addColor("Up", "Up Line Color", "", core.rgb(0, 255, 0)); 
	 indicator.parameters:addColor("UpDown", "Down in Up Trend Line Color", "", core.rgb(0, 200, 0)); 	 
	 indicator.parameters:addColor("Down", "Down Line Color", "", core.rgb(200, 0, 0)); 
	 indicator.parameters:addColor("DownUp", "Up in Down Trend Line Color", "", core.rgb(255, 0, 0)); 	 
end

-- Indicator instance initialization routine
-- Processes indicator parameters and creates output streams
-- TODO: Refine the first period calculation for each of the output streams.
-- TODO: Calculate all constants, create instances all subsequent indicators and load all required libraries
-- Parameters block
 
	
local first;
local source = nil;
local Period;

	
-- Routine
 function Prepare(nameOnly)   
 
    PriceSmooth=instance.parameters.PriceSmooth;
	IndexSmooth=instance.parameters.IndexSmooth;
	
    Period=instance.parameters.Period;
    local name = profile:id() .. "(" ..  instance.source:name() .. ", " ..  Period  .. ", " ..  PriceSmooth .. ", " ..  IndexSmooth.. ")";
    instance:name(name); 


    if   (nameOnly) then
        return;
    end
	
 
	
	source = instance.source
	first=source:first()+Period ; 
	
 
	
	
    Line = instance:addStream("    Line", core.Line, name, "    Line", instance.parameters.Up, first);
    Line:setPrecision(math.max(2, instance.source:getPrecision()));
    Line:setWidth(instance.parameters.width);
    Line:setStyle(instance.parameters.style);
    Line:addLevel(0);

    Trend = instance:addInternalStream(0, 0);	
    Temp = instance:addInternalStream(0, 0);	
end


function Update(period, mode)
 
 if period < first then
 return; 
 end
 
 local min,max=mathex.minmax(source, period-Period+1, period);
 
 
 
    Temp[period]= PriceSmooth*((source.close[period]-min)/(max-min)-0.5)+PriceSmooth*Temp[period-1];
	if Temp[period] > 0.9999 then
	Temp[period]= 0.9999;
    elseif Temp[period] < -0.9999 then
	Temp[period]= -0.9999;	
	end
	
    Line[period]=IndexSmooth*math.log((1.0+Temp[period])/(1.0-Temp[period]))+IndexSmooth*Line[period-1]; 
	
   if Line[period]> 0 then
   Trend[period]=1;   
   elseif Line[period]< 0 then
   Trend[period]=-1;      
   else  
   Trend[period]  =Trend[period-1];
   end
   
    if Line[period] >0 and Line[period]> Line[period-1] then
    Line:setColor(period, instance.parameters.Up);
    elseif Line[period] >0 and Line[period]< Line[period-1] then	
    Line:setColor(period, instance.parameters.UpDown);  
    elseif Line[period] <0 and Line[period]< Line[period-1] then
    Line:setColor(period, instance.parameters.Down); 
    elseif Line[period] <0 and Line[period]> Line[period-1] then		
    Line:setColor(period, instance.parameters.DownUp); 
	end
end