-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=15886
-- Id: 6339

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function Init()
    indicator:name("Serial MA indicator");
    indicator:description("Serial MA indicator");
    indicator:requiredSource(core.Tick);
    indicator:type(core.Indicator);

    indicator.parameters:addGroup("Style");
    indicator.parameters:addColor("Uclr", "Upper Color", "Upper Color", core.rgb(0, 255, 0));
    indicator.parameters:addColor("Lclr", "Lower Color", "Lower 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 UpperSerialMA=nil;
local LowerSerialMA=nil;
local UpperStream;
local LowerStream;
local StartPoint;

function Prepare(nameOnly)
    source = instance.source;
    first = source:first()+2;
    local name = profile:id() .. "(" .. source:name() .. ")";
    instance:name(name);
    if nameOnly then
        return;
    end
    UpperStream = instance:addInternalStream(first, 0);
    LowerStream = instance:addInternalStream(first, 0);
    UpperSerialMA = instance:addStream("UpperSerialMA", core.Line, name .. ".UpperSerialMA", "UpperSerialMA", instance.parameters.Uclr, first);
    LowerSerialMA = instance:addStream("LowerSerialMA", core.Line, name .. ".LowerSerialMA", "LowerSerialMA", instance.parameters.Lclr, first);
    UpperSerialMA:setWidth(instance.parameters.widthLinReg);
    UpperSerialMA:setStyle(instance.parameters.styleLinReg);
    LowerSerialMA:setWidth(instance.parameters.widthLinReg);
    LowerSerialMA:setStyle(instance.parameters.styleLinReg);
    core.host:execute ("addCommand", 1, "Start point", "Start point");
    StartPoint=nil;
end

function Update(period, mode)
   local StartBar;
   if StartPoint==nil then
    StartBar=first;
   else 
    StartBar=core.findDate(source, StartPoint, false);
   end 
   
   if StartBar==-1 then
   StartBar=first;
   end
   
   if (period>StartBar) then
    if source[period]>source[period-1] then
     UpperStream[period]=source[period];
     LowerStream[period]=LowerSerialMA[period-1];
    elseif source[period]<source[period-1] then
     UpperStream[period]=UpperSerialMA[period-1];
     LowerStream[period]=source[period];
    else
     UpperStream[period]=UpperSerialMA[period-1];
     LowerStream[period]=LowerSerialMA[period-1];
    end
    UpperSerialMA[period]=core.avg(UpperStream, core.range(StartBar, period));
    LowerSerialMA[period]=core.avg(LowerStream, core.range(StartBar, period));
   elseif period==StartBar then
    UpperStream[period]=source[period];
    LowerStream[period]=source[period];
    UpperSerialMA[period]=source[period];
    LowerSerialMA[period]=source[period];
   elseif period>=first and period<StartBar then
    UpperSerialMA[period]=nil; 
    LowerSerialMA[period]=nil; 
   end 
end

function AsyncOperationFinished(cookie, success, message)
 if cookie==1 then
  local t, c = core.parseCsv(message, ";");
  local PrevStartBar;
  if StartPoint==nil then
   PrevStartBar=first;
  else 
   PrevStartBar=core.findDate(source, StartPoint, false);
  end 
  StartPoint=t[1];
  local StartBar=core.findDate(source, StartPoint, false);
  instance:updateFrom(math.min(StartBar, PrevStartBar));
 end
end