-- Id: 14515

-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=62412

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function Init()
    indicator:name("Negative Volume Index with Real volume/Transactions");
    indicator:description("Negative Volume Index with Real volume/Transactions");
    indicator:requiredSource(core.Bar);
    indicator:type(core.Oscillator);

    indicator.parameters:addGroup("Calculation");
    indicator.parameters:addString("Ind", "Type of indicator", "", "Volume");
    indicator.parameters:addStringAlternative("Ind", "Volume", "", "Volume");
    indicator.parameters:addStringAlternative("Ind", "Transactions", "", "Transactions");
    indicator.parameters:addInteger("Period", "Period", "", 21);
    indicator.parameters:addString("Method", "Method", "", "MVA");
    indicator.parameters:addStringAlternative("Method", "MVA", "", "MVA");
    indicator.parameters:addStringAlternative("Method", "EMA", "", "EMA");
    indicator.parameters:addStringAlternative("Method", "KAMA", "", "KAMA");
    indicator.parameters:addStringAlternative("Method", "Wilder", "", "Wilder");
    indicator.parameters:addStringAlternative("Method", "LWMA", "", "LWMA");
    indicator.parameters:addStringAlternative("Method", "SineWMA", "", "SineWMA");
    indicator.parameters:addStringAlternative("Method", "TriMA", "", "TriMA");
    indicator.parameters:addStringAlternative("Method", "LSMA", "", "LSMA");
    indicator.parameters:addStringAlternative("Method", "SMMA", "", "SMMA");
    indicator.parameters:addStringAlternative("Method", "HMA", "", "HMA");
    indicator.parameters:addStringAlternative("Method", "ZeroLagEMA", "", "ZeroLagEMA");
    indicator.parameters:addStringAlternative("Method", "DEMA", "", "DEMA");
    indicator.parameters:addStringAlternative("Method", "T3", "", "T3");
    indicator.parameters:addStringAlternative("Method", "ITrend", "", "ITrend");
    indicator.parameters:addStringAlternative("Method", "Median", "", "Median");
    indicator.parameters:addStringAlternative("Method", "GeoMean", "", "GeoMean");
    indicator.parameters:addStringAlternative("Method", "REMA", "", "REMA");
    indicator.parameters:addStringAlternative("Method", "ILRS", "", "ILRS");
    indicator.parameters:addStringAlternative("Method", "IE/2", "", "IE/2");
    indicator.parameters:addStringAlternative("Method", "TriMAgen", "", "TriMAgen");
    indicator.parameters:addStringAlternative("Method", "JSmooth", "", "JSmooth");

    indicator.parameters:addGroup("Style");
    indicator.parameters:addColor("MainClr", "Main Color", "Main Color", core.rgb(0, 255, 0));
    indicator.parameters:addColor("SignalClr", "Signal Color", "Signal Color", core.rgb(255, 0, 0));
    indicator.parameters:addInteger("widthLinReg", "Line width", "Line width", 1, 1, 5);
    indicator.parameters:addInteger("styleLinReg", "Line style", "Line style", core.LINE_SOLID);
    indicator.parameters:setFlag("styleLinReg", core.FLAG_LINE_STYLE);
end

local first;
local source = nil;
local Period;
local Method;
local MA;
local Main=nil;
local Signal=nil;
local Ind;

local FirstStart;
local LastTime;

function Prepare(nameOnly)
    source = instance.source;
    Period=instance.parameters.Period;
	
	assert(core.indicators:findIndicator("AVERAGES") ~= nil, "Please, download and install AVERAGES.LUA indicator");    
	
    first = source:first()+2;
    local name = profile:id() .. "(" .. source:name() .. ", " .. instance.parameters.Period .. ", " .. instance.parameters.Method .. ")";
	
	 instance:name(name);
	
	if   (nameOnly) then
        return;
    end
	
     if instance.parameters.Ind=="Volume" then
      Ind=core.indicators:create("REAL VOLUME", source);
     else
      Ind=core.indicators:create("TRANSACTIONS", source);
     end
     FirstStart=true;
     LastTime=0;
   
	
	
    Main = instance:addStream("Main", core.Line, name .. ".Main", "Main", instance.parameters.MainClr, first);
    Main:setPrecision(math.max(2, instance.source:getPrecision()));
    MA = core.indicators:create("AVERAGES", Main, Method, Period, false);
    Signal = instance:addStream("Signal", core.Line, name .. ".Signal", "Signal", instance.parameters.SignalClr, first);
    Signal:setPrecision(math.max(2, instance.source:getPrecision()));
    Main:setWidth(instance.parameters.widthLinReg);
    Main:setStyle(instance.parameters.styleLinReg);
    Signal:setWidth(instance.parameters.widthLinReg);
    Signal:setStyle(instance.parameters.styleLinReg);
end

function Update(period, mode)
   if (period>first) then
        Ind:update(mode);
        Main[period]=Main[period-1];
        Signal[period]=Signal[period-1];
        if not(Ind.DATA:hasData(period)) then
            if period==first+1 then
                FirstStart=true;
            end    
            return;
        elseif FirstStart then
            FirstStart=false;
            instance:updateFrom(first);    
        elseif LastTime~=source:date(period) and period==source:size()-1 then
            LastTime=source:date(period);
            instance:updateFrom(period-10);
        end

    if Ind.DATA[period]<Ind.DATA[period-1] then
     Main[period]=Main[period-1]*(1+(source.close[period]-source.close[period-1])/source.close[period-1]);
    end
    MA:update(mode);
    Signal[period]=MA.DATA[period];
   elseif period==first then
    Main[period]=1; 
   end 
end

function AsyncOperationFinished(cookie, success, message)

end