quantwave-core 0.1.3

use crate::indicators::metadata::IndicatorMetadata;
use crate::traits::Next;

/// Heikin-Ashi Candlesticks
/// HA_Close = (Open + High + Low + Close) / 4
/// HA_Open = (prev_HA_Open + prev_HA_Close) / 2
/// HA_High = max(High, HA_Open, HA_Close)
/// HA_Low = min(Low, HA_Open, HA_Close)
#[derive(Debug, Clone)]
pub struct HeikinAshi {
    prev_ha_open: Option<f64>,
    prev_ha_close: Option<f64>,
}

impl HeikinAshi {
    pub fn new() -> Self {
        Self {
            prev_ha_open: None,
            prev_ha_close: None,
        }
    }
}

impl Next<(f64, f64, f64, f64)> for HeikinAshi {
    type Output = (f64, f64, f64, f64); // (HA_Open, HA_High, HA_Low, HA_Close)

    fn next(&mut self, (open, high, low, close): (f64, f64, f64, f64)) -> Self::Output {
        let ha_close = (open + high + low + close) / 4.0;

        let ha_open = match (self.prev_ha_open, self.prev_ha_close) {
            (Some(prev_open), Some(prev_close)) => (prev_open + prev_close) / 2.0,
            _ => (open + close) / 2.0,
        };

        let ha_high = high.max(ha_open).max(ha_close);
        let ha_low = low.min(ha_open).min(ha_close);

        self.prev_ha_open = Some(ha_open);
        self.prev_ha_close = Some(ha_close);

        (ha_open, ha_high, ha_low, ha_close)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use proptest::prelude::*;
    use serde::Deserialize;
    use std::fs;
    use std::path::Path;

    #[derive(Debug, Deserialize)]
    struct HACase {
        open: Vec<f64>,
        high: Vec<f64>,
        low: Vec<f64>,
        close: Vec<f64>,
        expected_open: Vec<f64>,
        expected_high: Vec<f64>,
        expected_low: Vec<f64>,
        expected_close: Vec<f64>,
    }

    #[test]
    fn test_heikin_ashi_gold_standard() {
        let manifest_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
        let manifest_path = Path::new(&manifest_dir);
        let path = manifest_path.join("tests/gold_standard/heikin_ashi.json");
        let path = if path.exists() {
            path
        } else {
            manifest_path
                .parent()
                .unwrap()
                .join("tests/gold_standard/heikin_ashi.json")
        };
        let content = fs::read_to_string(path).unwrap();
        let case: HACase = serde_json::from_str(&content).unwrap();

        let mut ha = HeikinAshi::new();
        for i in 0..case.open.len() {
            let (o, h, l, c) = ha.next((case.open[i], case.high[i], case.low[i], case.close[i]));
            approx::assert_relative_eq!(o, case.expected_open[i], epsilon = 1e-6);
            approx::assert_relative_eq!(h, case.expected_high[i], epsilon = 1e-6);
            approx::assert_relative_eq!(l, case.expected_low[i], epsilon = 1e-6);
            approx::assert_relative_eq!(c, case.expected_close[i], epsilon = 1e-6);
        }
    }

    fn heikin_ashi_batch(data: Vec<(f64, f64, f64, f64)>) -> Vec<(f64, f64, f64, f64)> {
        let mut ha = HeikinAshi::new();
        data.into_iter().map(|x| ha.next(x)).collect()
    }

    proptest! {
        #[test]
        fn test_heikin_ashi_parity(input in prop::collection::vec((0.0..100.0, 0.0..100.0, 0.0..100.0, 0.0..100.0), 1..100)) {
            let mut adj_input = Vec::with_capacity(input.len());
            for (o, h, l, c) in input {
                let o_f: f64 = o;
                let h_f: f64 = h;
                let l_f: f64 = l;
                let c_f: f64 = c;
                let high = h_f.max(o_f).max(l_f).max(c_f);
                let low = l_f.min(o_f).min(h_f).min(c_f);
                adj_input.push((o_f, high, low, c_f));
            }

            let mut ha = HeikinAshi::new();
            let mut streaming_results = Vec::with_capacity(adj_input.len());
            for &val in &adj_input {
                streaming_results.push(ha.next(val));
            }

            let batch_results = heikin_ashi_batch(adj_input);

            for (s, b) in streaming_results.iter().zip(batch_results.iter()) {
                approx::assert_relative_eq!(s.0, b.0, epsilon = 1e-6);
                approx::assert_relative_eq!(s.1, b.1, epsilon = 1e-6);
                approx::assert_relative_eq!(s.2, b.2, epsilon = 1e-6);
                approx::assert_relative_eq!(s.3, b.3, epsilon = 1e-6);
            }
        }
    }

    #[test]
    fn test_heikin_ashi_basic() {
        let mut ha = HeikinAshi::new();

        // Bar 1: O=10, H=12, L=8, C=11
        // HA_Close = (10+12+8+11)/4 = 41/4 = 10.25
        // HA_Open = (10+11)/2 = 10.5
        // HA_High = max(12, 10.5, 10.25) = 12
        // HA_Low = min(8, 10.5, 10.25) = 8
        let (o1, h1, l1, c1) = ha.next((10.0, 12.0, 8.0, 11.0));
        assert_eq!(o1, 10.5);
        assert_eq!(h1, 12.0);
        assert_eq!(l1, 8.0);
        assert_eq!(c1, 10.25);

        // Bar 2: O=11, H=13, L=10, C=12
        // HA_Close = (11+13+10+12)/4 = 46/4 = 11.5
        // HA_Open = (10.5 + 10.25)/2 = 20.75 / 2 = 10.375
        // HA_High = max(13, 10.375, 11.5) = 13
        // HA_Low = min(10, 10.375, 11.5) = 10
        let (o2, h2, l2, c2) = ha.next((11.0, 13.0, 10.0, 12.0));
        assert_eq!(o2, 10.375);
        assert_eq!(h2, 13.0);
        assert_eq!(l2, 10.0);
        assert_eq!(c2, 11.5);
    }
}

pub const HEIKIN_ASHI_METADATA: IndicatorMetadata = IndicatorMetadata {
    name: "Heikin-Ashi",
    description: "Heikin-Ashi candles filter market noise to reveal the underlying trend.",
    params: &[],
    formula_source: "https://www.investopedia.com/trading/heikin-ashi-better-candlestick/",
    formula_latex: r#"
\[
HA_{Close} = \frac{O + H + L + C}{4} \\ HA_{Open} = \frac{HA_{Open, t-1} + HA_{Close, t-1}}{2}
\]
"#,
    gold_standard_file: "heikin_ashi.json",
    category: "Classic",
};