# ============================================================
# MIZAN presents: Cross-Examination — EMA crossover — thinkScript · v1.0
# mizanquant.com/free · free & open source · a QWERTY Options Inc. tool
#
# WHAT IT DOES
# The oldest trick in the book, done properly. A fast and a slow
# moving average, a cloud between them colored by who is on top, and
# arrows when the fast line overtakes the slow one under questioning.
# Two things most versions skip: arrows can wait for the candle to
# close (default on) so an intrabar wobble cannot paint and erase
# them, and the alerts say actual words instead of a blank string.
# Crossovers lag by design; that is the cost of their calm. It
# describes the tape; it does not advise.
#
# ORIGINALITY NOTE
# An EMA crossover is generic public methodology older than the
# terminal you are reading this on. This implementation is written
# from scratch in-house; no code is shared with any other version.
#
# INSTALL (thinkorswim desktop)
# Charts > Studies > Edit Studies > Create > delete the template,
# paste this whole file, name it, OK, Apply.
# ============================================================

declare upper;

# ----- INPUTS -----
input priceSource = close;
input fastLength = 13;
input slowLength = 48;
input avgType = AverageType.EXPONENTIAL;
input confirmOnClose = yes;      # arrows wait for the bar to close
input showCloud = yes;
input showArrows = yes;
input showStatusLabel = yes;

# ----- THE TWO WITNESSES -----
plot FastLine = MovingAverage(avgType, priceSource, fastLength);
FastLine.SetDefaultColor(Color.CYAN);
FastLine.SetLineWeight(1);

plot SlowLine = MovingAverage(avgType, priceSource, slowLength);
SlowLine.SetDefaultColor(Color.LIGHT_GRAY);
SlowLine.SetLineWeight(1);

AddCloud(if showCloud then FastLine else Double.NaN, SlowLine, Color.DARK_GREEN, Color.DARK_RED);

# ----- THE CROSSING, OPTIONALLY CLOSE-CONFIRMED -----
def rawUp = FastLine crosses above SlowLine;
def rawDn = FastLine crosses below SlowLine;

def barClosed = !IsNaN(close[-1]);
def upSignal = if confirmOnClose then rawUp and barClosed else rawUp;
def dnSignal = if confirmOnClose then rawDn and barClosed else rawDn;

plot CrossUp = if showArrows and upSignal then low else Double.NaN;
CrossUp.SetPaintingStrategy(PaintingStrategy.ARROW_UP);
CrossUp.SetDefaultColor(Color.GREEN);
CrossUp.SetLineWeight(3);

plot CrossDown = if showArrows and dnSignal then high else Double.NaN;
CrossDown.SetPaintingStrategy(PaintingStrategy.ARROW_DOWN);
CrossDown.SetDefaultColor(Color.RED);
CrossDown.SetLineWeight(3);

# ----- STATUS -----
def fastOnTop = FastLine > SlowLine;
def spreadTicks = AbsValue(FastLine - SlowLine) / TickSize();
AddLabel(showStatusLabel,
    (if fastOnTop then "FAST OVER SLOW" else "SLOW OVER FAST") + " | spread " + Round(spreadTicks, 1) + " ticks",
    if fastOnTop then Color.GREEN else Color.RED);

# ----- ALERTS THAT SPEAK -----
Alert(upSignal, "Cross-Examination: fast " + fastLength + " crossed above slow " + slowLength, Alert.BAR, Sound.Chimes);
Alert(dnSignal, "Cross-Examination: fast " + fastLength + " crossed below slow " + slowLength, Alert.BAR, Sound.Bell);

# ----- SCAN EXPORTS -----
plot ScanCrossUp = if upSignal then 1 else 0;
ScanCrossUp.Hide();

plot ScanCrossDown = if dnSignal then 1 else 0;
ScanCrossDown.Hide();

plot ScanFastOnTop = if fastOnTop then 1 else 0;
ScanFastOnTop.Hide();

# Educational tool. It describes market conditions; it does not give
# advice, and no output is a recommendation to buy or sell anything.
# Trading involves substantial risk of loss. mizanquant.com/terms