-- More information about this indicator can be found at:
--http://fxcodebase.com/code/viewtopic.php?f=17&t=63097


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--+------------------------------------------------------------------+
-- initializes the indicator
function Init()
    indicator:name("Schaff Trend Cycle");
    indicator:description("");
    indicator:requiredSource(core.Tick);
    indicator:type(core.Oscillator);
    indicator.parameters:addGroup("Calculation");	 
    indicator.parameters:addInteger("C", "Schaff cycle periods", "", 10, 2, 10000);
    indicator.parameters:addInteger("S", "Short periods", "", 23, 2, 10000);
    indicator.parameters:addInteger("L", "Long periods", "", 50, 2, 10000);
	
	indicator.parameters:addGroup("Style");	
    indicator.parameters:addColor("clrSCHTC", "Color of the line", "", core.rgb(0, 255, 0));
	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:addGroup("OB/OS Levels");	
    indicator.parameters:addDouble("overbought", "Overbought Level","", 10);
    indicator.parameters:addDouble("oversold","Oversold Level","", 90);
    indicator.parameters:addInteger("level_overboughtsold_width","Line width","", 1, 1, 5);
    indicator.parameters:addInteger("level_overboughtsold_style", "Line Style","", core.LINE_SOLID);
    indicator.parameters:addColor("level_overboughtsold_color", "Line Color","", core.rgb(128, 128, 128));
    indicator.parameters:setFlag("level_overboughtsold_style", core.FLAG_LEVEL_STYLE);
end

local firstmcd = 0;
local firstst = 0;
local first = 0;
local S = 0;
local L = 0;
local C = 0;
local source = nil;
local out = nil;
local wmas, wmal;
local st, mcd
local data1;
local first2;
-- initializes the instance of the indicator
function Prepare(nameOnly)
    source = instance.source;
    S = instance.parameters.S;
    L = instance.parameters.L;
    C = instance.parameters.C;

  
    local name = profile:id() .. "(" .. source:name() .. "," .. C .. "," .. S .. "," .. L .. ")";    
	 instance:name(name);
	if   (nameOnly) then
        return;
    end
	
	 wmas = core.indicators:create("EMA", source, S);
    wmal = core.indicators:create("EMA", source, L);

    firstmcd = wmal.DATA:first();
    mcd = instance:addInternalStream(firstmcd, 0);
    firstst = firstmcd + C;
	first2 = firstst + C;
    st = instance:addInternalStream(firstst, 0);
    data1 = instance:addInternalStream(firstst, 0);
	data2 = instance:addInternalStream(first2, 0);
	
	
	out = instance:addStream("SCHTC", core.Line, name, "SCHTC", instance.parameters.clrSCHTC,  first2)
	out:addLevel(instance.parameters.oversold, instance.parameters.level_overboughtsold_style, instance.parameters.level_overboughtsold_width, instance.parameters.level_overboughtsold_color);
	out:addLevel(instance.parameters.overbought, instance.parameters.level_overboughtsold_style, instance.parameters.level_overboughtsold_width, instance.parameters.level_overboughtsold_color);    
	out:addLevel(0, instance.parameters.level_overboughtsold_style, instance.parameters.level_overboughtsold_width, instance.parameters.level_overboughtsold_color);    
	out:addLevel(100, instance.parameters.level_overboughtsold_style, instance.parameters.level_overboughtsold_width, instance.parameters.level_overboughtsold_color);	
	out:setPrecision (2);	
	out:setWidth(instance.parameters.width);
    out:setStyle(instance.parameters.style);   
   
end

-- calculate the value
function Update(period, mode)
    if (period  < firstmcd) then
    return;
	end
	
        wmas:update(mode);
        wmal:update(mode);
        mcd[period] = wmas.DATA[period] - wmal.DATA[period];
 
    if (period < firstst) then
	return;
	end
    
     min, max = mathex.minmax(mcd, period-C+1, period);
       
       
		
		if (max - min)> 0 then
		st[period] = ((mcd[period] - min) / (max - min)) * 100;        
		else
		st[period]=st[period-1];
		end
		
		data1[period]=data1[period-1]+0.5*(st[period]-data1[period-1]);
  
    if (period < first2) then
	return;
	end
	 
	min, max = mathex.minmax(data1, period-C+1, period);
	
	if (max - min)> 0 then	
	data2[period]= ((data1[period] - min) / (max - min)) * 100;
    else
	data2[period]=data2[period-1];
    end	
	 
 	  out[period]=out[period-1]+0.5*(data2[period]-out[period-1]);
 
  
 
end