use crate::constants;
use crate::energy::consumption::EnergyConsumption;
use crate::utils::math_utils::median;

pub struct ConsumptionCache {
    nb_vals: usize,
    values: Vec<EnergyConsumption>,
}

impl ConsumptionCache {
    pub fn new(nb_vals: usize) -> Self {
        Self {
            nb_vals,
            values: vec![],
        }
    }

    pub fn add_value(&mut self, value: EnergyConsumption) {
        if self.values.len() >= self.nb_vals {
            self.values.remove(0);
        }

        self.values.push(value);
    }

    pub fn median_value(&self) -> EnergyConsumption {
        if self.values.is_empty() {
            return constants::FALLBACK_PRODUCTION_VALUE;
        }

        median(&self.values)
    }
}

#[cfg(test)]
pub mod test {
    use crate::constants;
    use crate::energy::consumption_cache::ConsumptionCache;

    #[test]
    fn empty_vec() {
        let cache = ConsumptionCache::new(10);
        assert_eq!(cache.median_value(), constants::FALLBACK_PRODUCTION_VALUE);
    }

    #[test]
    fn single_value() {
        let mut cache = ConsumptionCache::new(10);
        cache.add_value(-10);
        assert_eq!(cache.median_value(), -10);
    }

    #[test]
    fn four_values() {
        let mut cache = ConsumptionCache::new(10);
        cache.add_value(50);
        cache.add_value(-10);
        cache.add_value(-10);
        cache.add_value(-10000);
        assert_eq!(cache.median_value(), -10);
    }

    #[test]
    fn many_values() {
        let mut cache = ConsumptionCache::new(6);

        for i in 0..1000 {
            cache.add_value(-i);
        }

        cache.add_value(10);
        cache.add_value(50);
        cache.add_value(-10);
        cache.add_value(-10);
        cache.add_value(-30);
        cache.add_value(-10000);
        assert_eq!(cache.median_value(), -10);
    }
}