-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=42262
-- Id: 9430

--+------------------------------------------------------------------+
--|                               Copyright © 2018, Gehtsoft USA LLC |
--|                                            http://fxcodebase.com |
--+------------------------------------------------------------------+
--|                                      Developed by : Mario Jemic  |
--|                                          mario.jemic@gmail.com   |
--+------------------------------------------------------------------+
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--+------------------------------------------------------------------+

function Init()
    indicator:name("Stretch oscillator");
    indicator:description("Stretch oscillator");
    indicator:requiredSource(core.Bar);
    indicator:type(core.Oscillator);

    indicator.parameters:addGroup("Calculation");
    indicator.parameters:addInteger("St_Period", "St_Period", "", 10);
    indicator.parameters:addInteger("Av_Period", "Av_Period", "", 12);
    indicator.parameters:addString("Method", "Method", "", "SMMA");
    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("Hclr", "Histogram color", "Histogram color", core.rgb(0, 255, 0));
    indicator.parameters:addColor("Sclr", "Signal color", "Signal color", core.rgb(255, 0, 0));
    indicator.parameters:addInteger("Swidth", "Signal width", "Signal width", 2, 1, 5);
    indicator.parameters:addInteger("Sstyle", "Signal style", "Signal style", core.LINE_DASH);
    indicator.parameters:setFlag("Sstyle", core.FLAG_LINE_STYLE);
end

local first;
local source = nil;
local St_Period;
local Av_Period;
local Method;
local Abs_HO_LO;
local Abs_LO;
local MA;
local Stretch=nil;
local Signal=nil;

function Prepare(nameOnly)
    source = instance.source;
    St_Period=instance.parameters.St_Period;
    Av_Period=instance.parameters.Av_Period;
    Method=instance.parameters.Method;
    first = source:first();
    local name = profile:id() .. "(" .. source:name() .. ", " .. instance.parameters.St_Period .. ", " .. instance.parameters.Av_Period .. ", " .. instance.parameters.Method .. ")";
    instance:name(name);
    if nameOnly then
        return;
    end
	
	assert(core.indicators:findIndicator("AVERAGES") ~= nil, "Please, download and install AVERAGES.LUA indicator");  
	
    Abs_HO_LO = instance:addInternalStream(0, 0);
    Stretch = instance:addStream("Stretch", core.Bar, name .. ".Stretch", "Stretch", instance.parameters.Hclr, first+St_Period);
    Stretch:setPrecision(math.max(2, instance.source:getPrecision()));
    MA = core.indicators:create("AVERAGES", Stretch, Method, Av_Period, false);
    Signal = instance:addStream("Signal", core.Line, name .. ".Signal", "Signal", instance.parameters.Sclr, MA.DATA:first());
    Signal:setPrecision(math.max(2, instance.source:getPrecision()));
    Signal:setWidth(instance.parameters.Swidth);
    Signal:setStyle(instance.parameters.Sstyle);
end

function Update(period, mode)
   if period>first then
    local Abs_HO=math.abs(source.high[period]-source.open[period]);
    local Abs_LO=math.abs(source.low[period]-source.open[period]);
    Abs_HO_LO[period]=math.min(Abs_HO, Abs_LO);
    if period>first+St_Period then
     local Avg=mathex.avg(Abs_HO_LO, period-St_Period+1, period);
     Stretch[period]=Avg;
	 end
	 if period>MA.DATA:first() then
     MA:update(mode);
     Signal[period]=MA.DATA[period];
    end
   end 
end