-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=59574
-- Id: 10061

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function Init()
    indicator:name("Double top indicator")
    indicator:description("Double top indicator")
    indicator:requiredSource(core.Bar)
    indicator:type(core.Indicator)

    indicator.parameters:addGroup("Calculation")
    indicator.parameters:addInteger("MinHeight", "Min. height of peak (in pips)", "", 10)
    indicator.parameters:addInteger("MaxDist", "Max. distance between peaks (in bars)", "", 20)
    indicator.parameters:addInteger("MinBars", "Min. number of bars after the peak (in bars)", "", 3)

    indicator.parameters:addGroup("Style")
    indicator.parameters:addColor("Tclr1", "Top color", "Top color", core.rgb(0, 128, 0))
    indicator.parameters:addColor("Tclr2", "Double top color", "Double top color", core.rgb(0, 255, 0))
    indicator.parameters:addColor("Bclr1", "Bottom color", "Bottom color", core.rgb(128, 0, 0))
    indicator.parameters:addColor("Bclr2", "Double bottom color", "Double bottom color", core.rgb(255, 0, 0))
    indicator.parameters:addInteger("DotSize", "Dot size", "Dot size", 3, 1, 5)
end

local first
local source = nil
local MinHeight
local MaxDist
local MinBars
local MinHeightPip
local Top = nil
local DoubleTop = nil
local Bottom = nil
local DoubleBottom = nil
local line, Tclr1, Tclr2, Bclr1, Bclr2

function Prepare(nameOnly)
    source = instance.source
    MinHeight = instance.parameters.MinHeight
    MaxDist = instance.parameters.MaxDist
    MinBars = instance.parameters.MinBars
    MinHeightPip = MinHeight * source:pipSize()
    first = source:first() + MinBars
    local name =
        profile:id() ..
        "(" .. source:name() .. ", " .. instance.parameters.MinHeight .. ", " .. instance.parameters.MaxDist .. ")"
    instance:name(name)
    if nameOnly then
        return
    end
    Tclr1 = instance.parameters.Tclr1
    Tclr2 = instance.parameters.Tclr2
    Bclr1 = instance.parameters.Bclr1
    Bclr2 = instance.parameters.Bclr2
    Top = instance:addStream("Top", core.Dot, name .. ".Top", "Top", instance.parameters.Tclr1, first)
    DoubleTop =
        instance:addStream("DoubleTop", core.Dot, name .. ".DoubleTop", "DoubleTop", instance.parameters.Tclr2, first)
    Bottom = instance:addStream("Bottom", core.Dot, name .. ".Bottom", "Bottom", instance.parameters.Bclr1, first)
    DoubleBottom =
        instance:addStream(
        "DoubleBottom",
        core.Dot,
        name .. ".DoubleBottom",
        "DoubleBottom",
        instance.parameters.Bclr2,
        first
    )
    line = instance:addStream("line", core.Line, "line", "line", Tclr1, 0, 0)
    Top:setWidth(instance.parameters.DotSize)
    DoubleTop:setWidth(instance.parameters.DotSize)
    Bottom:setWidth(instance.parameters.DotSize)
    DoubleBottom:setWidth(instance.parameters.DotSize)
end

function GetFrom(period)
    local from = line:getBookmark(1);
    if from == period - MinBars then
        from = line:getBookmark(2)
    end
    return from;
end

function Update(period, mode)
    if period > first then
        if IsTop(period - MinBars) then
            Top[period - MinBars] = source.high[period - MinBars]
            local from = GetFrom(period);
            if from >= 0 then
                core.drawLine(line, core.range(from, period), line[from], from, Top[period - MinBars], period - MinBars, Tclr1);
            end
            local old = line:getBookmark(1);
            line:setBookmark(1, period - MinBars);
            if old ~= -1 and old ~= period - MinBars then
                line:setBookmark(2, old);
            end
        else
            Top[period - MinBars] = nil
        end
        if IsBottom(period - MinBars) then
            Bottom[period - MinBars] = source.low[period - MinBars]
            local from = GetFrom(period);
            if from >= 0 then
                core.drawLine(line, core.range(from, period), line[from], from, Bottom[period - MinBars], period - MinBars, Bclr1);
            end
            local old = line:getBookmark(1);
            line:setBookmark(1, period - MinBars);
            if old ~= -1 and old ~= period - MinBars then
                line:setBookmark(2, old);
            end
        else
            Bottom[period - MinBars] = nil
        end
        local Res
        if Top[period - MinBars] == source.high[period - MinBars] then
            Res = FindPrevTop(period - MinBars)
            if Res ~= nil then
                DoubleTop[period - MinBars] = source.high[period - MinBars]
                local from = GetFrom(period);
                if from >= 0 then
                    core.drawLine(line, core.range(from, period), line[from], from, DoubleTop[period - MinBars], period - MinBars, Tclr2);
                end
                local old = line:getBookmark(1);
                line:setBookmark(1, period - MinBars);
                if old ~= -1 and old ~= period - MinBars then
                    line:setBookmark(2, old);
                end
            end
        end
        if Bottom[period - MinBars] == source.low[period - MinBars] then
            Res = FindPrevBottom(period - MinBars)
            if Res ~= nil then
                DoubleBottom[period - MinBars] = source.low[period - MinBars]
                local from = GetFrom(period);
                if from >= 0 then
                    core.drawLine(line, core.range(from, period), line[from], from, DoubleBottom[period - MinBars], period - MinBars, Bclr2);
                end
                local old = line:getBookmark(1);
                line:setBookmark(1, period - MinBars);
                if old ~= -1 and old ~= period - MinBars then
                    line:setBookmark(2, old);
                end
            end
        end
    end
end

function FindPrevTop(index)
    local i = index - 1
    while i > first and i >= index - MaxDist do
        if Top[i] == source.high[i] then
            return i
        end
        i = i - 1
    end
    return nil
end

function FindPrevBottom(index)
    local i = index - 1
    while i > first and i >= index - MaxDist do
        if Bottom[i] == source.low[i] then
            return i
        end
        i = i - 1
    end
    return nil
end

function IsTop(index)
    local i
    local Fl = true
    for i = 1, MinBars, 1 do
        if source.high[index + i] >= source.high[index] then
            Fl = false
        end
    end
    if Fl then
        i = index - 1
        while i > first do
            if source.high[i] >= source.high[index] then
                return false
            end
            if source.high[index] - source.low[i] >= MinHeightPip then
                return true
            end
            i = i - 1
        end
    end
    return false
end

function IsBottom(index)
    local i
    local Fl = true
    for i = 1, MinBars, 1 do
        if source.low[index + i] <= source.low[index] then
            Fl = false
        end
    end
    if Fl then
        i = index - 1
        while i > first do
            if source.low[i] <= source.low[index] then
                return false
            end
            if source.high[i] - source.low[index] >= MinHeightPip then
                return true
            end
            i = i - 1
        end
    end
    return false
end