-- More information about this indicator can be found at:
-- https://fxcodebase.com/code/viewtopic.php?f=17&t=71118

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-- Indicator profile initialization routine

function Init()
    indicator:name("AM Demodulator");
    indicator:description("");
    indicator:requiredSource(core.Bar);
    indicator:type(core.Oscillator);
	
	indicator.parameters:addGroup("Calculation"); 
    indicator.parameters:addInteger("Period1", "1. Period", "", 4, 1, 2000);
    indicator.parameters:addInteger("Period2", "2. Period", "", 8, 1, 2000); 
 
	
	indicator.parameters:addGroup("Style"); 	
    indicator.parameters:addColor("color", "Line Color", "", core.rgb(255, 0, 0));
	indicator.parameters:addInteger("style", "Line Style", "", core.LINE_SOLID);
    indicator.parameters:setFlag("style", core.FLAG_LEVEL_STYLE);	
	indicator.parameters:addInteger("width", "Line Width", "", 3, 1, 5);
	
end

-- Indicator instance initialization routine
-- Processes indicator parameters and creates output streams
-- Parameters block

 
local Period1; 
local Period2; 
local first;
local source = nil;
 
local Oscillator;  
local Deriv;
local Envel;
-- Routine
 function Prepare(nameOnly)   
 
 
    Period1= instance.parameters.Period1;
    Period2= instance.parameters.Period2;	
	
	local Parameters= Period1 .. ", " .. Period2;
 
    local name = profile:id() .. "(" ..  instance.source:name() ..  ", " ..  Parameters .. ")";
    instance:name(name); 


    if   (nameOnly) then
        return;
    end

    
			
    source = instance.source; 
    first=source:first()+1;
	
	Deriv= instance:addInternalStream(0, 0);
    Envel= instance:addInternalStream(0, 0);
 
	Oscillator = instance:addStream("Oscillator" , core.Line, " Oscillator"," Oscillator",instance.parameters.color, first+Period1+Period2 );
	Oscillator:setWidth(instance.parameters.width);
    Oscillator:setStyle(instance.parameters.style);
    Oscillator:setPrecision(math.max(2, source:getPrecision()));
	
	
end

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

    
	if period < first
	then
	return;
	end
    Deriv[period]=math.abs(source.close[period]-source.open[period]);
 
	
    if period < first+Period1
	then
	return;
	end	
	Envel[period]=mathex.max(Deriv, period-Period1+1, period);
	
	if period < first+Period1+Period2
	then
	return;
	end	
	
	
    Oscillator[period]=mathex.avg(Envel, period-Period2+1, period);
				  
end