raidillon/engine/src/system.rs

use indexmap::IndexMap;
use raidillon_core::scene::Scene;
use raidillon_core::DebugUIBuffer;
use raidillon_platform::PlatformContext;
use std::any::TypeId;
use std::cell::RefCell;
use std::rc::Rc;

pub struct SystemContext<'a> {
    // TODO: time delta etc.
    pub scene: &'a mut Scene,
    pub platform_context: PlatformContext,
    pub debug_ui_buffer: Rc<RefCell<DebugUIBuffer>>,
}

pub trait System {
    /// Initialize the system.
    fn initialize(&mut self) {}
    /// Spawn the first entities of the world.
    fn load_world(&mut self, _ctx: &mut SystemContext) {}
    fn handle_event(&mut self, _ctx: &mut SystemContext) {}
    fn fixed_update(&mut self, _ctx: &mut SystemContext) {}
    fn frame_update(&mut self, _ctx: &mut SystemContext) {}
}

pub struct SystemManager {
    pub systems: IndexMap<TypeId, Box<dyn System>>,
}

impl SystemManager {
    pub fn new() -> Self {
        Self {
            systems: IndexMap::default(),
        }
    }

    pub fn add<S: System + Default + 'static>(&mut self) {
        self.systems
            .insert(TypeId::of::<S>(), Box::new(S::default()));
    }

    pub fn remove<S: 'static>(&mut self) {
        self.systems.shift_remove(&TypeId::of::<S>());
    }
}