-- Indicator profile initialization routine
function Init()
    indicator:name("Stochastic Fast (Modified)");
    indicator:description("Stochastic Oscillator is a momentum indicator that shows the location of the current close relative to the high/low range over a set number of periods. Closing levels that are consistently near the top of the range indicate accumulation (buying pressure) and those near the bottom of the range indicate distribution (selling pressure).");
    indicator:requiredSource(core.Bar);
    indicator:type(core.Oscillator);

    indicator.parameters:addInteger("K", "%K", "", 14, 2, 1000);
    indicator.parameters:addInteger("D", "%D", "", 3, 2, 1000);
    indicator.parameters:addColor("clrFirst", "%K color", "", core.rgb(0, 255, 0));
    indicator.parameters:addColor("clrSecond", "%D color", "", core.rgb(255, 0, 0));
end

-- Indicator instance initialization routine
local k;
local d;

local source = nil;

-- Streams block
local iK = nil;
local K = nil;
local D = nil;

-- Routine
function Prepare()
    k = instance.parameters.K;
    d = instance.parameters.D;
    source = instance.source;

    local name = profile:id() .. "(" .. source:name() .. ", " .. k .. ", " .. d .. ")";
    instance:name(name);
    K = instance:addStream("K", core.Line, name .. ".K", "K", instance.parameters.clrFirst, source:first() + k);
    D = instance:addStream("D", core.Line, name .. ".D", "D", instance.parameters.clrSecond, source:first() + k + d);
end

-- Indicator calculation routine
function Update(period)
    if period >= K:first() then
        local kRange = core.rangeTo(period, k);
        local ll = core.min(source.low, kRange);
        local hh = core.max(source.high, kRange);
        K[period] = 100 * ((source.close[period] - ll) / (hh - ll));
    end
    if period >= D:first() then
        local dRange = core.rangeTo(period, d);
        D[period] = core.avg(K, dRange);
    end
end