//! ODF Stark 展宽辅助函数。
//!
//! 重构自 TLUSTY `odfhst.f`
//!
//! 用于 ODF1 的辅助例程，替代多次调用 STARKA。

use crate::state::constants::{TWO, UN};
use crate::state::model::StrAux;
use crate::state::odfpar::MFRO;

/// ODF Stark 展宽辅助函数。
///
/// 用于 ODF1 的辅助例程，计算 Stark 展宽的线轮廓。
///
/// # 参数
///
/// * `n` - 频率点数
/// * `fxk` - 线宽参数
/// * `fid` - 振子强度
/// * `wp` - 权重
/// * `wl` - 波长
/// * `alam` - 频率数组
/// * `straux` - Stark 展宽参数
/// * `sg` - 输出：Stark 展宽数组
///
/// # 示例
///
/// ```
/// use tlusty_rust::math::odfhst::odfhst;
/// use tlusty_rust::state::model::StrAux;
///
/// let straux = StrAux::default();
/// let alam = vec![1.0, 2.0, 3.0];
/// let mut sg = vec![0.0; 3];
///
/// odfhst(3, 1.0, 0.5, 1.0, 1215.0, &alam, &straux, &mut sg);
/// ```
pub fn odfhst(
    n: usize,
    fxk: f64,
    fid: f64,
    wp: f64,
    wl: f64,
    alam: &[f64],
    straux: &StrAux,
    sg: &mut [f64],
) {
    // 常数参数
    const F0: f64 = -0.5758228;
    const F1: f64 = 0.4796232;
    const F2: f64 = 0.07209481;
    const AL: f64 = 1.26;

    const SD: f64 = 0.5641895;
    const SLO: f64 = -2.5;
    const THRA: f64 = 1.5;
    const BL1: f64 = 1.14;
    const BL2: f64 = 11.4;

    const SAC: f64 = 0.08;
    const THR: f64 = THRA * TWO;

    let betad = straux.betad;
    let adh = straux.adh;
    let divh = straux.divh;

    // 防止除零
    let betad1 = if betad.abs() > 1e-30 { UN / betad } else { 0.0 };
    let fxk1 = if fxk.abs() > 1e-30 { UN / fxk } else { 0.0 };
    let fidwp = fid * wp;

    // for a > 1 Doppler core + asymptotic Holtzmark wing with division point DIV
    if adh > AL {
        for ij in 0..n {
            let beta = (alam[ij] - wl).abs() * fxk1;
            let xd = beta * betad1;

            let st = if xd <= divh {
                SD * (-xd * xd).exp() * betad1
            } else {
                THR * beta.powf(SLO)
            };

            sg[ij] = st * fidwp;
        }
    } else {
        // empirical formula for a < 1
        for ij in 0..n {
            let beta = (alam[ij] - wl).abs() * fxk1;
            let xd = beta * betad1;

            let st = if beta <= BL1 {
                SAC
            } else if beta < BL2 {
                let xl = beta.ln();
                let fl = (F0 * xl + F1) * xl;
                F2 * fl.exp()
            } else {
                THR * beta.powf(SLO)
            };

            sg[ij] = st * fidwp;
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_odfhst_adh_gt_al() {
        let mut straux = StrAux::default();
        straux.adh = 2.0; // > AL = 1.26
        straux.betad = 1.0;
        straux.divh = 1.0;

        let alam = vec![1200.0, 1215.0, 1230.0];
        let mut sg = vec![0.0; 3];

        odfhst(3, 1.0, 0.5, 1.0, 1215.0, &alam, &straux, &mut sg);

        // 中间点（wl=1215.0）应该有最大值
        assert!(sg[1] > sg[0]);
        assert!(sg[1] > sg[2]);
    }

    #[test]
    fn test_odfhst_adh_lt_al() {
        let mut straux = StrAux::default();
        straux.adh = 0.5; // < AL = 1.26
        straux.betad = 1.0;
        straux.divh = 1.0;

        let alam = vec![1200.0, 1215.0, 1230.0];
        let mut sg = vec![0.0; 3];

        odfhst(3, 1.0, 0.5, 1.0, 1215.0, &alam, &straux, &mut sg);

        // 所有值应该是正的
        for &s in &sg {
            assert!(s >= 0.0);
        }
    }

    #[test]
    fn test_odfhst_zero_betad() {
        let mut straux = StrAux::default();
        straux.adh = 2.0;
        straux.betad = 0.0; // 零值
        straux.divh = 1.0;

        let alam = vec![1200.0, 1215.0, 1230.0];
        let mut sg = vec![0.0; 3];

        // 不应该 panic
        odfhst(3, 1.0, 0.5, 1.0, 1215.0, &alam, &straux, &mut sg);
    }
}