use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct HorizonPoint {
    pub az_deg: i32,
    pub alt_deg: f64,
}

/// Linear interpolation of horizon altitude at a given azimuth.
/// The profile must have points at every integer degree 0–359.
pub fn horizon_alt(az_deg: f64, profile: &[HorizonPoint]) -> f64 {
    if profile.is_empty() {
        return 15.0;
    }

    let az = az_deg.rem_euclid(360.0);
    let lo_idx = az.floor() as usize % 360;
    let hi_idx = (lo_idx + 1) % 360;
    let frac = az.fract();

    let lo_alt = profile
        .iter()
        .find(|p| p.az_deg == lo_idx as i32)
        .map(|p| p.alt_deg)
        .unwrap_or(15.0);
    let hi_alt = profile
        .iter()
        .find(|p| p.az_deg == hi_idx as i32)
        .map(|p| p.alt_deg)
        .unwrap_or(15.0);

    lo_alt + frac * (hi_alt - lo_alt)
}