-- Available @ http://fxcodebase.com/code/viewtopic.php?f=17&t=64929


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function Init()
    indicator:name("Custom Time Frame Candle Tick View");
    indicator:description("A chart will add a new Candle After passing of Set Number of Base Tick Time Frame elements.");
    indicator:requiredSource(core.Tick);
    indicator:type(core.View);

    indicator.parameters:addGroup("Calculation");
	indicator.parameters:addString("Instrument","Instrument","", "EUR/USD");
    indicator.parameters:setFlag("Instrument", core.FLAG_INSTRUMENTS);
		
    indicator.parameters:addInteger("BarSize", "Size of bar in second", "", 10);
	
	indicator.parameters:addBoolean("type", "Price Type","", true);
    indicator.parameters:setFlag("type", core.FLAG_BIDASK);
   
    indicator.parameters:addGroup("Range");
    indicator.parameters:addDate("from", "From","", -10);
    indicator.parameters:addDate("to", "To","", 0);
    indicator.parameters:setFlag("to", core.FLAG_DATE_OR_NULL);
end
local Last;
local loading;
local History;
local open, high, low, close, volume;
local offer;
local offset;
local LastTime;
local Instrument;
local Count;
local FIRST;
local Old;

local BarSizeSec;
local currentBarSec;
local firstBarSec;

-- initializes the instance of the indicator
function Prepare(onlyName)

    FIRST=true;
    BarSizeSec = instance.parameters.BarSize;
	TF = instance.parameters.TF;
	Instrument = instance.parameters.Instrument;

    local name = profile:id().. ", " .. Instrument .. ", " .. BarSizeSec .. "T" 
    instance:name(name);

    if onlyName then
        return ;
    end
	
    -- check whether the instrument is available
    local offers = core.host:findTable("offers");
    local enum = offers:enumerator();
    local row=nil;

    row = enum:next();
    while row ~= nil do
        if row.Instrument == Instrument then
            break;
        end
        row = enum:next();
    end
	

    assert(row ~= nil, "Selected instrument is not available");
    offer = row.OfferID;

    instance:initView(Instrument, row.Digits, row.PointSize, true, true);

    History = core.host:execute("getHistory", 1000, Instrument, "t1", instance.parameters.from, instance.parameters.to, instance.parameters.type);
    loading = true;
	
    if instance.parameters.to == 0 then 
        core.host:execute("subscribeTradeEvents", 2000, "offers");  
	end
	
    core.host:execute("setStatus", "Loading");

    open = instance:addStream("open", core.Line, name .. "." .. "Open", "open", 0, 0, 0);
    high = instance:addStream("high", core.Line, name .. "." .. "High", "high", 0, 0, 0);
    low = instance:addStream("low", core.Line, name .. "." .. "Low", "low", 0, 0, 0);
    close = instance:addStream("close", core.Line, name .. "." .. "Close", "close", 0, 0, 0);

    instance:createCandleGroup("candle", "candle", open, high, low, close, TF);
    firstBarSec = 0;
end

function Update(period)
end

function AsyncOperationFinished(cookie, success, message)

    if cookie == 1000 then	    
		 handleHistory(); 
         core.host:execute("setStatus", "");		 
    elseif cookie == 2000 then  	
        loading = false;  
        handleUpdate() 		          			 		
    end	
end

local NEW = false;
function calcValue( Index, period)

    if period < History:first() then
        return;
    end	
		
    local currentBarSec = math.floor(History:date(period)*86400);        
    local diff =  currentBarSec - firstBarSec;
	
    if diff >= BarSizeSec  then    
        NEW=true;
	end
        
    if  NEW then   
 
        instance:addViewBar(History:date(period));	            
        Index = Index + 1;
        firstBarSec = math.floor(History:date(period)*86400); 
		open[Index] = History[period];
        close[Index] = History[period];
        high[Index] = History[period];
        low[Index] = History[period];
               
        NEW=false;	
    else
       
        low[Index] = math.min(low[Index], History[period]); 
        high[Index]  = math.max(high[Index], History[period]);        		
		close[Index] = History[period];  	
    end

	return Index;          
 end

function handleHistory()

    local s = History:size() - 1;
    local i;
    local current = open:size() - 1;
    
    for i = 1, s, 1 do
        current = calcValue(current, i);
    end
    
    loading = false;
    LastTime=History:size()-1; 
end

function handleUpdate()

    local current = open:size() - 1;	
    local i;		   
		   
    local i;
    for i = LastTime, History:size()-1, 1 do
        current = calcValue( current  ,i);
    end 	
	 
    LastTime=History:size()-1;	
end