-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=20

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function Init()
    indicator:name("Donchian Channel")
    indicator:description(
        "The simple trend-following indicator. Shows highest high and lowest low for the specified number of periods."
    )
    indicator:requiredSource(core.Bar)
    indicator:type(core.Indicator)

    indicator.parameters:addGroup("Calculation")
    indicator.parameters:addInteger("N", "Number of periods", "", 20, 2, 10000)
    indicator.parameters:addString("AC", "Analyze the current period", "", "yes")
    indicator.parameters:addStringAlternative("AC", "no", "", "no")
    indicator.parameters:addStringAlternative("AC", "yes", "", "yes")

    indicator.parameters:addString("shift_type", "Shift type", "", "pips");
    indicator.parameters:addStringAlternative("shift_type", "Pips", "", "pips");
    indicator.parameters:addStringAlternative("shift_type", "Percent", "", "%");
    indicator.parameters:addDouble("vshift", "Vertical Shift", "", 0);
	indicator.parameters:addDouble("hshift", "Horizontal Shift", "", 0);

    indicator.parameters:addGroup("Style")
    indicator.parameters:addColor("clrDU", "Color of the Up line", "", core.rgb(255, 255, 0))
    indicator.parameters:addInteger("width1", "Line width", "", 1, 1, 5)
    indicator.parameters:addInteger("style1", "Line style", "", core.LINE_SOLID)
    indicator.parameters:setFlag("style1", core.FLAG_LINE_STYLE)
    indicator.parameters:addColor("clrDN", "Color of the Down line", "", core.rgb(255, 255, 0))
    indicator.parameters:addInteger("width2", "Line width", "", 1, 1, 5)
    indicator.parameters:addInteger("style2", "Line style", "", core.LINE_SOLID)
    indicator.parameters:setFlag("style2", core.FLAG_LINE_STYLE)
    indicator.parameters:addColor("clrDM", "Color of the middle line", "", core.rgb(255, 255, 0))
    indicator.parameters:addInteger("width3", "Line width", "", 1, 1, 5)
    indicator.parameters:addInteger("style3", "Line style", "", core.LINE_SOLID)
    indicator.parameters:setFlag("style3", core.FLAG_LINE_STYLE)
    indicator.parameters:addString("SM", "Show middle line", "", "no")
    indicator.parameters:addStringAlternative("SM", "no", "", "no")
    indicator.parameters:addStringAlternative("SM", "yes", "", "yes")
end

local first = 0
local n = 0
local ac = true
local sm = false
local source = nil
local dn = nil
local du = nil
local dm = nil
local shift_type, vshift,hshift;

-- initializes the instance of the indicator
function Prepare(nameOnly)
    source = instance.source
    n = instance.parameters.N
    ac = (instance.parameters.AC == "yes")
    sm = (instance.parameters.SM == "yes")
    shift_type = instance.parameters.shift_type;
    vshift = instance.parameters.vshift;
	hshift= instance.parameters.hshift;

    first = n + source:first() - 1
    if (not ac) then
        first = first + 1
    end
    local name = profile:id() .. "(" .. source:name() .. "," .. n .. ")"
    instance:name(name)

    if (nameOnly) then
        return
    end

    dn = instance:addStream("DU", core.Line, name .. ".DU", "DU", instance.parameters.clrDU, math.max(first, first+(hshift) ), hshift)
    dn:setWidth(instance.parameters.width1)
    dn:setStyle(instance.parameters.style1)
    du = instance:addStream("DN", core.Line, name .. ".DN", "DN", instance.parameters.clrDN, math.max(first, first+ (hshift) ), hshift)
    du:setWidth(instance.parameters.width2)
    du:setStyle(instance.parameters.style2)
    if (sm) then
        dm = instance:addStream("DM", core.Line, name .. ".DM", "DM", instance.parameters.clrDM, math.max(first, first +(hshift) ), hshift)
        dm:setWidth(instance.parameters.width3)
        dm:setStyle(instance.parameters.style3)
    end
end

-- calculate the value
function Update(period)


                
    if (period <= first + math.abs(hshift) ) then
	return;
	end
	
	
        local range
        if (ac) then
            range = core.rangeTo(period, n)
        else
            range = core.rangeTo(period - 1, n)
        end
        if shift_type == "pips" then
            du[period+hshift] = core.max(source.high, range) + vshift * source:pipSize();
            dn[period+hshift] = core.min(source.low, range) - vshift * source:pipSize();
        else
            du[period+hshift] = core.max(source.high, range) * (1 + vshift / 100);
            dn[period+hshift] = core.min(source.low, range) / (1 + vshift / 100);
        end
        if (sm) then
            dm[period+hshift] = (du[period+hshift] + dn[period+hshift]) / 2
        end
    

    local Width = (du[period+hshift] - dn[period+hshift])

    local Value = " Channel width " .. string.format("%." .. 1 .. "f", Width / source:pipSize()) .. " Pips"
    Value = Value .. " Channel width " .. string.format("%." .. 4 .. "f", Width / ((dn[period+hshift] + Width) / 100)) .. " %"
    core.host:execute("setStatus", Value)
end