use crate::{
    N_INF,
    drift::{ConstantDrift, Drift},
    gaussian::Gaussian,
    rating::Rating,
};

/// Per-history, temporal state for someone competing.
///
/// Renamed from `Agent` in T2; the former `.player` field is now
/// `.rating` to match the `Player → Rating` rename.
#[derive(Debug)]
pub struct Competitor<D: Drift = ConstantDrift> {
    pub rating: Rating<D>,
    pub message: Gaussian,
    pub last_time: i64,
}

impl<D: Drift> Competitor<D> {
    pub(crate) fn receive(&self, elapsed: i64) -> Gaussian {
        if self.message != N_INF {
            self.message
                .forget(self.rating.drift.variance_delta(elapsed))
        } else {
            self.rating.prior
        }
    }
}

impl Default for Competitor<ConstantDrift> {
    fn default() -> Self {
        Self {
            rating: Rating::default(),
            message: N_INF,
            last_time: i64::MIN,
        }
    }
}

pub(crate) fn clean<'a, D: Drift + 'a, C: Iterator<Item = &'a mut Competitor<D>>>(
    competitors: C,
    last_time: bool,
) {
    for c in competitors {
        c.message = N_INF;
        if last_time {
            c.last_time = i64::MIN;
        }
    }
}