quantwave-core 0.1.3

use crate::indicators::metadata::{IndicatorMetadata, ParamDef};
use crate::indicators::roofing_filter::RoofingFilter;
use crate::traits::Next;
use std::collections::VecDeque;

/// Ehlers Stochastic (MESA Stochastic)
/// 
/// Based on John Ehlers' "Anticipating Turning Points".
/// It is a standard Stochastic calculation applied to the output of a Roofing Filter.
/// This removes the distortion caused by Spectral Dilation in standard Stochastics.
#[derive(Debug, Clone)]
pub struct EhlersStochastic {
    roof: RoofingFilter,
    stoch_period: usize,
    roof_window: VecDeque<f64>,
}

impl EhlersStochastic {
    pub fn new(hp_period: usize, ss_period: usize, stoch_period: usize) -> Self {
        Self {
            roof: RoofingFilter::new(hp_period, ss_period),
            stoch_period,
            roof_window: VecDeque::with_capacity(stoch_period),
        }
    }
}

impl Next<f64> for EhlersStochastic {
    type Output = f64;

    fn next(&mut self, input: f64) -> Self::Output {
        let roof_val = self.roof.next(input);
        self.roof_window.push_front(roof_val);
        if self.roof_window.len() > self.stoch_period {
            self.roof_window.pop_back();
        }
        
        let mut min = f64::MAX;
        let mut max = f64::MIN;
        for &v in &self.roof_window {
            if v < min { min = v; }
            if v > max { max = v; }
        }
        
        if max == min {
            50.0
        } else {
            100.0 * (roof_val - min) / (max - min)
        }
    }
}

pub const EHLERS_STOCHASTIC_METADATA: IndicatorMetadata = IndicatorMetadata {
    name: "Ehlers Stochastic",
    description: "A Stochastic oscillator applied to the output of a Roofing Filter to eliminate Spectral Dilation.",
    params: &[
        ParamDef { name: "hp_period", default: "48", description: "HighPass critical period" },
        ParamDef { name: "ss_period", default: "10", description: "SuperSmoother critical period" },
        ParamDef { name: "stoch_period", default: "20", description: "Stochastic lookback period" },
    ],
    formula_source: "https://github.com/lavs9/quantwave/blob/main/references/Ehlers%20Papers/Anticipating Turning Points.pdf",
    formula_latex: r#"
\[
Roof = RoofingFilter(HP, SS)
\]
\[
Stoch = 100 \times \frac{Roof - \min(Roof, L)}{\max(Roof, L) - \min(Roof, L)}
\]
"#,
    gold_standard_file: "ehlers_stochastic.json",
    category: "Ehlers DSP",
};

#[cfg(test)]
mod tests {
    use super::*;
    use crate::traits::Next;
    use crate::test_utils::{load_gold_standard, assert_indicator_parity};
    use proptest::prelude::*;

    #[test]
    fn test_ehlers_stochastic_gold_standard() {
        let case = load_gold_standard("ehlers_stochastic");
        let es = EhlersStochastic::new(48, 10, 20);
        assert_indicator_parity(es, &case.input, &case.expected);
    }

    #[test]
    fn test_ehlers_stochastic_basic() {
        let mut es = EhlersStochastic::new(48, 10, 20);
        let inputs = vec![10.0, 11.0, 12.0, 13.0, 14.0, 15.0];
        for input in inputs {
            let res = es.next(input);
            assert!(res >= 0.0 && res <= 100.0);
        }
    }

    proptest! {
        #[test]
        fn test_ehlers_stochastic_parity(
            inputs in prop::collection::vec(1.0..100.0, 50..100),
        ) {
            let hp = 48;
            let ss = 10;
            let stoch = 20;
            let mut es = EhlersStochastic::new(hp, ss, stoch);
            let streaming_results: Vec<f64> = inputs.iter().map(|&x| es.next(x)).collect();
            
            // Batch implementation
            let mut batch_results = Vec::with_capacity(inputs.len());
            let mut roof = RoofingFilter::new(hp, ss);
            let mut roof_vals = Vec::new();
            
            for &input in &inputs {
                let r_val = roof.next(input);
                roof_vals.push(r_val);
                
                let start = if roof_vals.len() > stoch { roof_vals.len() - stoch } else { 0 };
                let window = &roof_vals[start..];
                
                let mut min = f64::MAX;
                let mut max = f64::MIN;
                for &v in window {
                    if v < min { min = v; }
                    if v > max { max = v; }
                }
                
                let res = if max == min {
                    50.0
                } else {
                    100.0 * (r_val - min) / (max - min)
                };
                batch_results.push(res);
            }
            
            for (s, b) in streaming_results.iter().zip(batch_results.iter()) {
                approx::assert_relative_eq!(s, b, epsilon = 1e-10);
            }
        }
    }
}