-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=1102

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function Init()
    indicator:name("FAN of EMA")
    indicator:description("")
    indicator:requiredSource(core.Tick)
    indicator:type(core.Indicator)

    indicator.parameters:addInteger("Period_1", "First period", "No description", 5)
    indicator.parameters:addString("Method", "Method", "", "Add")
    indicator.parameters:addStringAlternative("Method", "Add", "", "Add")
    indicator.parameters:addStringAlternative("Method", "Mult", "", "Mult")

    indicator.parameters:addInteger("K", "K", "No description", 2)
    indicator.parameters:addInteger("N", "Count of MA", "No description", 5)
end

local Period1
local K
local N
local Method

local first
local source = nil
local buffs = {}

local Inds = {}
function Prepare(nameOnly)
    Period1 = instance.parameters.Period_1
    K = instance.parameters.K
    N = instance.parameters.N
    Method = instance.parameters.Method

    local name =
        profile:id() ..
        "(" .. instance.source:name() .. ", " .. Period1 .. ", " .. K .. ", " .. N .. ", " .. Method .. ")"
    instance:name(name)

    if (nameOnly) then
        return
    end

    source = instance.source
    local Period = Period1
    for i = 1, N, 1 do
        Ind = core.indicators:create("EMA", source, Period)
        Inds[i] = Ind
        if Method == "Mult" then
            Period = Period * K
        else
            Period = Period + K
        end
    end

    first = Inds[N].DATA:first() + 2

    for i = 1, N, 1 do
        if i < N / 3 then
            Color = core.rgb(i * 155 * 3 / N + 100, 0, 0)
        elseif i >= N / 3 and i < 2 * N / 3 then
            Color = core.rgb(0, (i - N / 3) * 155 / N + 100, 0)
        else
            Color = core.rgb(0, 0, (i - N * 2 / 3) * 155 / N + 100)
        end
        buffs[i] = instance:addStream("buff" .. i, core.Line, name .. ".buff" .. i, "buff" .. i, Color, first)
    end
end

function Update(period, mode)
    if (period > first) then
        for i = 1, N, 1 do
            Inds[i]:update(mode)
            buffs[i][period] = Inds[i].DATA[period]
        end
    end
end