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//! Doji candlestick pattern.
use crate::error::{Error, Result};
use crate::ohlcv::Candle;
use crate::traits::Indicator;
/// Doji — a candle whose body is negligible relative to its range.
///
/// A Doji prints whenever the absolute distance between open and close is
/// small compared to the total `high − low` range. It is the canonical
/// indecision bar and a building block for many three-bar reversal patterns.
///
/// ```text
/// body = |close − open|
/// range = high − low
/// doji = body <= body_threshold * range
/// ```
///
/// The output is `+1.0` when a Doji is detected and `0.0` otherwise. Doji is
/// directionless — no `−1.0` is emitted. Pattern-shape check only — no trend
/// filter is applied; combine with a trend indicator for actionable signals.
///
/// # Example
///
/// ```
/// use wickra_core::{Candle, Doji, Indicator};
///
/// let mut indicator = Doji::default();
/// let candle = Candle::new(10.0, 11.0, 9.0, 10.0, 1.0, 0).unwrap();
/// assert_eq!(indicator.update(candle), Some(1.0));
/// ```
#[derive(Debug, Clone)]
pub struct Doji {
body_threshold: f64,
has_emitted: bool,
}
impl Default for Doji {
fn default() -> Self {
Self::new()
}
}
impl Doji {
/// Construct a Doji detector with the default body threshold (`0.1`).
pub const fn new() -> Self {
Self {
body_threshold: 0.1,
has_emitted: false,
}
}
/// Construct a Doji detector with a custom body / range threshold.
///
/// `body_threshold` must lie in `(0, 1]`.
pub fn with_threshold(body_threshold: f64) -> Result<Self> {
if !(body_threshold > 0.0 && body_threshold <= 1.0) {
return Err(Error::InvalidPeriod {
message: "doji body threshold must lie in (0, 1]",
});
}
Ok(Self {
body_threshold,
has_emitted: false,
})
}
/// Configured body / range threshold.
pub fn body_threshold(&self) -> f64 {
self.body_threshold
}
}
impl Indicator for Doji {
type Input = Candle;
type Output = f64;
fn update(&mut self, candle: Candle) -> Option<f64> {
self.has_emitted = true;
let range = candle.high - candle.low;
if range <= 0.0 {
return Some(0.0);
}
let body = (candle.close - candle.open).abs();
Some(if body <= self.body_threshold * range {
1.0
} else {
0.0
})
}
fn reset(&mut self) {
self.has_emitted = false;
}
fn warmup_period(&self) -> usize {
1
}
fn is_ready(&self) -> bool {
self.has_emitted
}
fn name(&self) -> &'static str {
"Doji"
}
}
#[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 rejects_invalid_threshold() {
assert!(Doji::with_threshold(0.0).is_err());
assert!(Doji::with_threshold(-0.1).is_err());
assert!(Doji::with_threshold(1.5).is_err());
}
#[test]
fn accepts_valid_threshold() {
let d = Doji::with_threshold(0.05).unwrap();
assert!((d.body_threshold() - 0.05).abs() < 1e-12);
}
#[test]
fn accessors_and_metadata() {
let d = Doji::default();
assert_eq!(d.name(), "Doji");
assert_eq!(d.warmup_period(), 1);
assert!(!d.is_ready());
assert!((d.body_threshold() - 0.1).abs() < 1e-12);
}
#[test]
fn obvious_doji_is_one() {
let mut d = Doji::new();
// open == close, full range -> body / range = 0.
assert_eq!(d.update(c(10.0, 11.0, 9.0, 10.0, 0)), Some(1.0));
assert!(d.is_ready());
}
#[test]
fn marubozu_is_not_doji() {
// Big body, no shadows -> body / range = 1.0 > 0.1.
let mut d = Doji::new();
assert_eq!(d.update(c(10.0, 12.0, 10.0, 12.0, 0)), Some(0.0));
}
#[test]
fn zero_range_yields_zero() {
let mut d = Doji::new();
assert_eq!(d.update(c(10.0, 10.0, 10.0, 10.0, 0)), Some(0.0));
}
#[test]
fn batch_equals_streaming() {
let candles: Vec<Candle> = (0..40)
.map(|i| {
let base = 100.0 + i as f64;
c(base, base + 2.0, base - 2.0, base + 1.0, i)
})
.collect();
let mut a = Doji::new();
let mut b = Doji::new();
assert_eq!(
a.batch(&candles),
candles.iter().map(|x| b.update(*x)).collect::<Vec<_>>()
);
}
#[test]
fn reset_clears_state() {
let mut d = Doji::new();
d.update(c(10.0, 11.0, 9.0, 10.0, 0));
assert!(d.is_ready());
d.reset();
assert!(!d.is_ready());
}
}