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//! Morning Star / Evening Star candlestick pattern.
use crate::ohlcv::Candle;
use crate::traits::Indicator;
/// Morning Star / Evening Star — a 3-bar reversal pattern.
///
/// **Morning Star** (bullish, `+1.0`):
/// 1. Bar 1 is a long red candle.
/// 2. Bar 2 has a small body (the "star") — colour does not matter.
/// 3. Bar 3 is a long green candle that closes above the midpoint of Bar 1.
///
/// **Evening Star** (bearish, `−1.0`): the mirror image — long green, small
/// body, long red closing below Bar 1's midpoint.
///
/// The "long" qualifier is enforced by requiring the outer bars' bodies to be
/// at least twice the size of the star's body. Pattern-shape check only — no
/// trend filter is applied; combine with a trend indicator for actionable
/// signals.
///
/// # Signed ±1 encoding
///
/// This detector already emits the uniform candlestick sign convention shared
/// across the pattern family — `+1.0` bullish, `−1.0` bearish, `0.0` no
/// pattern — so it drops straight into a machine-learning feature matrix where
/// the bullish and bearish variants of the pattern occupy a single dimension.
///
/// # Example
///
/// ```
/// use wickra_core::{Candle, Indicator, MorningEveningStar};
///
/// let mut indicator = MorningEveningStar::new();
/// indicator.update(Candle::new(12.0, 12.2, 9.5, 10.0, 1.0, 0).unwrap());
/// indicator.update(Candle::new(9.9, 10.1, 9.7, 9.95, 1.0, 1).unwrap());
/// let out = indicator
/// .update(Candle::new(10.1, 12.0, 10.0, 11.8, 1.0, 2).unwrap());
/// assert_eq!(out, Some(1.0));
/// ```
#[derive(Debug, Clone, Default)]
pub struct MorningEveningStar {
prev: Option<Candle>,
prev_prev: Option<Candle>,
has_emitted: bool,
}
impl MorningEveningStar {
/// Construct a new Morning / Evening Star detector.
pub const fn new() -> Self {
Self {
prev: None,
prev_prev: None,
has_emitted: false,
}
}
}
impl Indicator for MorningEveningStar {
type Input = Candle;
type Output = f64;
fn update(&mut self, candle: Candle) -> Option<f64> {
self.has_emitted = true;
let pp = self.prev_prev;
let p = self.prev;
self.prev_prev = self.prev;
self.prev = Some(candle);
let (Some(b1), Some(b2)) = (pp, p) else {
return Some(0.0);
};
let body1 = (b1.close - b1.open).abs();
let body2 = (b2.close - b2.open).abs();
let body3 = (candle.close - candle.open).abs();
if body1 <= 0.0 || body3 <= 0.0 {
return Some(0.0);
}
// Star body must be small relative to the outer bars.
if body1 < 2.0 * body2 || body3 < 2.0 * body2 {
return Some(0.0);
}
let mid1 = f64::midpoint(b1.open, b1.close);
let bar1_red = b1.close < b1.open;
let bar1_green = b1.close > b1.open;
let bar3_green = candle.close > candle.open;
let bar3_red = candle.close < candle.open;
if bar1_red && bar3_green && candle.close > mid1 {
Some(1.0)
} else if bar1_green && bar3_red && candle.close < mid1 {
Some(-1.0)
} else {
Some(0.0)
}
}
fn reset(&mut self) {
self.prev = None;
self.prev_prev = None;
self.has_emitted = false;
}
fn warmup_period(&self) -> usize {
3
}
fn is_ready(&self) -> bool {
self.has_emitted
}
fn name(&self) -> &'static str {
"MorningEveningStar"
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::traits::BatchExt;
fn c(open: f64, high: f64, low: f64, close: f64, ts: i64) -> Candle {
Candle::new(open, high, low, close, 1.0, ts).unwrap()
}
#[test]
fn accessors_and_metadata() {
let m = MorningEveningStar::new();
assert_eq!(m.name(), "MorningEveningStar");
assert_eq!(m.warmup_period(), 3);
assert!(!m.is_ready());
}
#[test]
fn morning_star_is_plus_one() {
let mut m = MorningEveningStar::new();
// Long red 12 -> 10 (body 2). Star small body. Long green 10.1 -> 11.8 (body 1.7).
// Mid of bar 1 = 11. Bar 3 closes at 11.8 > 11.
assert_eq!(m.update(c(12.0, 12.2, 9.5, 10.0, 0)), Some(0.0));
assert_eq!(m.update(c(9.9, 10.1, 9.7, 9.95, 1)), Some(0.0));
assert_eq!(m.update(c(10.1, 12.0, 10.0, 11.8, 2)), Some(1.0));
}
#[test]
fn evening_star_is_minus_one() {
let mut m = MorningEveningStar::new();
// Long green 10 -> 12, star, long red 11.9 -> 10.2 (body 1.7).
// Mid of bar 1 = 11. Bar 3 closes at 10.2 < 11.
assert_eq!(m.update(c(10.0, 12.2, 9.8, 12.0, 0)), Some(0.0));
assert_eq!(m.update(c(12.1, 12.3, 11.9, 12.05, 1)), Some(0.0));
assert_eq!(m.update(c(11.9, 12.0, 10.1, 10.2, 2)), Some(-1.0));
}
#[test]
fn big_star_body_is_not_star() {
let mut m = MorningEveningStar::new();
m.update(c(12.0, 12.2, 9.5, 10.0, 0));
// Star body 1.5 -> body1=2, body3 needs to be >= 3 to satisfy 2*body2.
m.update(c(9.5, 11.5, 9.5, 11.0, 1));
assert_eq!(m.update(c(10.1, 12.0, 10.0, 11.8, 2)), Some(0.0));
}
#[test]
fn first_two_bars_return_zero() {
let mut m = MorningEveningStar::new();
assert_eq!(m.update(c(12.0, 12.2, 9.5, 10.0, 0)), Some(0.0));
assert_eq!(m.update(c(9.9, 10.1, 9.7, 9.95, 1)), Some(0.0));
}
#[test]
fn batch_equals_streaming() {
let candles: Vec<Candle> = (0..40)
.map(|i| {
let base = 100.0 + i as f64;
match i % 3 {
0 => c(base + 2.0, base + 2.5, base - 0.5, base, i),
1 => c(base + 0.1, base + 0.3, base - 0.1, base + 0.15, i),
_ => c(base, base + 2.5, base - 0.5, base + 2.0, i),
}
})
.collect();
let mut a = MorningEveningStar::new();
let mut b = MorningEveningStar::new();
assert_eq!(
a.batch(&candles),
candles.iter().map(|x| b.update(*x)).collect::<Vec<_>>()
);
}
#[test]
fn reset_clears_state() {
let mut m = MorningEveningStar::new();
m.update(c(12.0, 12.2, 9.5, 10.0, 0));
m.update(c(9.9, 10.1, 9.7, 9.95, 1));
m.update(c(10.1, 12.0, 10.0, 11.8, 2));
assert!(m.is_ready());
m.reset();
assert!(!m.is_ready());
assert_eq!(m.update(c(12.0, 12.2, 9.5, 10.0, 0)), Some(0.0));
}
#[test]
fn doji_outer_bar_yields_zero() {
// Bar1 is a doji (body == 0): body1 == 0 -> guard triggers, returns 0.
let mut m = MorningEveningStar::new();
m.update(c(10.0, 11.0, 9.0, 10.0, 0)); // doji bar1
m.update(c(9.9, 10.1, 9.7, 9.95, 1));
assert_eq!(m.update(c(10.1, 12.0, 10.0, 11.8, 2)), Some(0.0));
}
#[test]
fn same_direction_bars_yield_zero() {
// Bar1 red, star small, bar3 also red (wrong direction) -> falls through to else 0.
let mut m = MorningEveningStar::new();
m.update(c(12.0, 12.2, 9.5, 10.0, 0)); // long red (body 2)
m.update(c(9.9, 10.1, 9.7, 9.95, 1)); // small star
// Bar3 red, closes below mid (11); doesn't match morning star (bar3 must be green)
// and also doesn't match evening star (bar1 must be green).
assert_eq!(m.update(c(11.0, 11.2, 9.0, 9.5, 2)), Some(0.0));
}
}