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//! contains system for sludge enemy AI

use std::cmp;

use specs::{prelude::*, System};

use crate::{engine::components::UnitComponent, unit::UnitType};

/// This system acts as an enemy AI, attacking the player if a sludge
/// exists and is in range of the [`Warrior`](crate::warrior::Warrior).
pub struct SludgeSystem {
    pub name: String,
}

impl SludgeSystem {
    pub fn new(name: String) -> SludgeSystem {
        SludgeSystem { name }
    }
}

impl<'a> System<'a> for SludgeSystem {
    type SystemData = WriteStorage<'a, UnitComponent>;

    fn run(&mut self, mut units: Self::SystemData) {
        let mut warrior_comp = None;
        let mut sludge_comps = Vec::new();
        for unit_comp in (&mut units).join() {
            match unit_comp.unit.unit_type {
                UnitType::Warrior => {
                    warrior_comp = Some(unit_comp);
                }
                UnitType::Sludge | UnitType::ThickSludge => {
                    sludge_comps.push(unit_comp);
                }
                _ => {}
            }
        }
        let warrior_comp = warrior_comp.unwrap();

        for sludge_comp in sludge_comps {
            let (wx, _) = warrior_comp.unit.position;
            let (sx, _) = sludge_comp.unit.position;
            let (hp, _) = sludge_comp.unit.hp;
            // if the Sludge is killed and the entity is deleted, but `world.maintain()` hasn't
            // been called yet, then we need to see if the Sludge is at 0 hp (dead) here.
            if hp > 0 && (wx - sx).abs() <= 1 {
                println!(
                    "{sludge:?} attacks {warrior}",
                    sludge = sludge_comp.unit.unit_type,
                    warrior = &self.name
                );
                let (current, max) = warrior_comp.unit.hp;
                let remaining = cmp::max(current - sludge_comp.unit.atk, 0);
                println!(
                    "{warrior} takes {atk} damage, {remaining} HP left",
                    warrior = &self.name,
                    atk = sludge_comp.unit.atk,
                    remaining = remaining
                );
                warrior_comp.unit.hp = (remaining, max);
            }
        }
    }
}