-- Id: 940

-- More information about this indicator can be found at:
-- http://fxcodebase.com/code/viewtopic.php?f=17&t=1362

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-- Indicator profile initialization routine
-- Defines indicator profile properties and indicator parameters
function Init()
    indicator:name("Kagi Chart");
    indicator:description("");
    indicator:requiredSource(core.Bar);
    indicator:type(core.Oscillator);

    indicator.parameters:addDouble("S", "Sensitivity in points", "", 5, 0.1, 100);
    indicator.parameters:addInteger("L", "Length in bars", "", 2, 1, 10);
    indicator.parameters:addString("PT", "Price type", "", "M");
    indicator.parameters:addStringAlternative("PT", "High", "", "H");
    indicator.parameters:addStringAlternative("PT", "Low", "", "L");
    indicator.parameters:addStringAlternative("PT", "Close", "", "C");
    indicator.parameters:addStringAlternative("PT", "Median", "", "M");
    indicator.parameters:addStringAlternative("PT", "Typical", "", "T");
    indicator.parameters:addStringAlternative("PT", "Weigthed", "", "W");

    indicator.parameters:addColor("LI", "Line color", "", core.rgb(128, 0, 0));
    indicator.parameters:addColor("LH", "Highlight color", "", core.rgb(255, 0, 0));
end

-- Indicator instance initialization routine
-- Processes indicator parameters and creates output streams
-- Parameters block
local S, L;
local LI, UL, DL, UL1, DL1;
local first;
local source = nil;
local price = nil;
local pip;
local host;

-- Streams block

-- Routine
function Prepare(nameOnly)
    source = instance.source;
    -- size of the box in pips
    S = instance.parameters.S * source:pipSize();
    L = instance.parameters.L;

    first = source:first();
    host = core.host;

    if instance.parameters.PT == "H" then
        price = source.high;
    elseif instance.parameters.PT == "L" then
        price = source.low;
    elseif instance.parameters.PT == "C" then
        price = source.close;
    elseif instance.parameters.PT == "M" then
        price = source.median;
    elseif instance.parameters.PT == "T" then
        price = source.typical;
    elseif instance.parameters.PT == "W" then
        price = source.weighted;
    end

    local name = profile:id() .. "(" .. price:name() .. ", " .. instance.parameters.S .. ")";
    instance:name(name);
	
	if   (nameOnly) then
        return;
    end

    LI = instance:addStream("L1", core.Line, name .. ".L1", "L1", instance.parameters.LI, first);
    LI:setPrecision(math.max(2, instance.source:getPrecision()));
    UL = instance:createTextOutput ("UL", "UL", "Wingdings", 8, core.H_Center, core.V_Top, instance.parameters.LI, 0);
    DL = instance:createTextOutput ("UL", "UL", "Wingdings", 8, core.H_Center, core.V_Bottom, instance.parameters.LI, 0);
    UL1 = instance:createTextOutput ("UL1", "UL1", "Wingdings", 8, core.H_Center, core.V_Top, instance.parameters.LH, 0);
    DL1 = instance:createTextOutput ("UL1", "UL1", "Wingdings", 8, core.H_Center, core.V_Bottom, instance.parameters.LH, 0);
end

local lastdate = nil;
local laststart = nil;

-- Indicator calculation routine
function Update(period)
    if lastdate ~= nil and lastdate > source:date(period) then
        lastdate = nil;
    end

    if period == source:size() - 1 then
        -- recalculate for the latest candle only
        if source:isAlive() then
            if lastdate == nil or lastdate ~= source:date(period) then
                lastdate = source:date(period);
                period = period - 1;
            else
                -- the last candle is still changing
                return ;
            end
        end
    else
        -- do not work until the collection is finished
        return ;
    end

    if period <= first then
        return ;
    end

    local i, kagi, start, count;
    kagi = {};
    start = {};
    count = 0;

    kagi[count] = price[first];
    start[count] = price:date(first);

    -- calcute kagi
    for i = first + 1, period, 1 do
        if count == 0 then
            if price[i] >= kagi[count] + S then
                count = count + 1;
                kagi[count] = price[i];
                start[count] = price:date(i);
            elseif price[i] <= kagi[count] - S then
                count = count + 1;
                kagi[count] = price[i];
                start[count] = price:date(i);
            end
        else
            if kagi[count] > kagi[count - 1] then
                if price[i] > kagi[count] then
                    kagi[count] = price[i];
                elseif price[i] < kagi[count] - S then
                    count = count + 1;
                    kagi[count] = price[i];
                    start[count] = price:date(i);
                end
            elseif kagi[count] < kagi[count - 1] then
                if price[i] < kagi[count] then
                    kagi[count] = price[i];
                elseif price[i] > kagi[count] + S then
                    count = count + 1;
                    kagi[count] = price[i];
                    start[count] = price:date(i);
                end
            end
        end
    end
    -- draw kagi
    local size1 = L;
    local i, j, p, date, label, previous, b2, b3, level;
    p = period - (count + 1) * size1;
    if laststart ~= nil then
        for i = math.max(laststart, 0), math.min(source:size(), p), 1 do
            LI[i] = nil;
            UL:setNoData(i);
            DL:setNoData(i);
            UL1:setNoData(i);
            DL1:setNoData(i);
        end
    end
    laststart = p;
    for i = 0, count, 1 do
        if p >= first then
            if i > 1 then
                date = core.dateToTable(host:execute("convertTime", 1, 4, start[i]));
                label = string.format("Begins: %02i/%02i/%02i %02i:%02i", date.month, date.day, date.year, date.hour, date.min);
                if kagi[i] > kagi[i - 1] then
                    if i > 2 and kagi[i] > kagi[i - 2] then
                        UL1:set(p, kagi[i], "\226", label);
                    else
                        UL:set(p, kagi[i], "\226", label);
                    end
                else
                    if i > 2 and kagi[i] < kagi[i - 2] then
                        DL1:set(p, kagi[i], "\225", label);
                    else
                        DL:set(p, kagi[i], "\225", label);
                    end
                end
            end
            for j = 0, size1 - 1, 1 do
                LI[p + j] = kagi[i];
            end
        end
        p = p + size1;
    end
end