// Library
use specs::{Entities, Join, Read, ReadStorage, System, WriteStorage};
use vek::*;

// Crate
use crate::{
    comp::{Dying, Stats},
    state::DeltaTime,
};

// Basic ECS AI agent system
pub struct Sys;

impl<'a> System<'a> for Sys {
    type SystemData = (
        Entities<'a>,
        Read<'a, DeltaTime>,
        WriteStorage<'a, Stats>,
        WriteStorage<'a, Dying>,
    );

    fn run(&mut self, (entities, dt, mut stats, mut dyings): Self::SystemData) {
        for (entity, mut stat) in (&entities, &mut stats).join() {
            if stat.should_die() && !stat.is_dead {
                // TODO: Replace is_dead with client states
                dyings.insert(
                    entity,
                    Dying {
                        cause: stat
                            .hp
                            .last_change
                            .expect("Nothing caused the entity to die")
                            .2, // Safe because damage is necessary for death
                    },
                );
                stat.is_dead = true;
            }
            if let Some(change) = &mut stat.hp.last_change {
                change.1 += dt.0 as f64;
            }
        }
    }
}