#![feature(
    never_type,
    try_blocks,
    trait_alias,
    control_flow_enum,
    let_chains,
    binary_heap_drain_sorted,
    fn_traits,
    unboxed_closures,
    tuple_trait,
    trait_upcasting
)]

pub mod ai;
pub mod data;
pub mod event;
pub mod gen;
pub mod rule;

pub use self::{
    data::Data,
    event::{Event, EventCtx, OnTick},
    rule::{Rule, RuleError},
};
use anymap2::SendSyncAnyMap;
use atomic_refcell::AtomicRefCell;
use common::resources::{Time, TimeOfDay};
use std::{
    any::type_name,
    ops::{Deref, DerefMut},
};
use tracing::{error, info};
use world::{IndexRef, World};

pub struct RtState {
    resources: SendSyncAnyMap,
    rules: SendSyncAnyMap,
    event_handlers: SendSyncAnyMap,
}

type RuleState<R> = AtomicRefCell<R>;
type EventHandlersOf<E> = Vec<Box<dyn Fn(&RtState, &World, IndexRef, &E) + Send + Sync + 'static>>;

impl RtState {
    pub fn new(data: Data) -> Self {
        let mut this = Self {
            resources: SendSyncAnyMap::new(),
            rules: SendSyncAnyMap::new(),
            event_handlers: SendSyncAnyMap::new(),
        }
        .with_resource(data);

        this.start_default_rules();

        this
    }

    pub fn with_resource<R: Send + Sync + 'static>(mut self, r: R) -> Self {
        self.resources.insert(AtomicRefCell::new(r));
        self
    }

    fn start_default_rules(&mut self) {
        info!("Starting default rtsim rules...");
        self.start_rule::<rule::migrate::Migrate>();
        self.start_rule::<rule::replenish_resources::ReplenishResources>();
        self.start_rule::<rule::report::ReportEvents>();
        self.start_rule::<rule::sync_npcs::SyncNpcs>();
        self.start_rule::<rule::simulate_npcs::SimulateNpcs>();
        self.start_rule::<rule::npc_ai::NpcAi>();
        self.start_rule::<rule::cleanup::CleanUp>();
    }

    pub fn start_rule<R: Rule>(&mut self) {
        info!("Initiating '{}' rule...", type_name::<R>());
        match R::start(self) {
            Ok(rule) => {
                self.rules.insert::<RuleState<R>>(AtomicRefCell::new(rule));
            },
            Err(e) => error!("Error when initiating '{}' rule: {}", type_name::<R>(), e),
        }
    }

    fn rule_mut<R: Rule>(&self) -> impl DerefMut<Target = R> + '_ {
        self.rules
            .get::<RuleState<R>>()
            .unwrap_or_else(|| {
                panic!(
                    "Tried to access rule '{}' but it does not exist",
                    type_name::<R>()
                )
            })
            .borrow_mut()
    }

    // TODO: Consider whether it's worth explicitly calling rule event handlers
    // instead of allowing them to bind event handlers. Less modular, but
    // potentially easier to deal with data dependencies?
    pub fn bind<R: Rule, E: Event>(
        &mut self,
        f: impl FnMut(EventCtx<R, E>) + Send + Sync + 'static,
    ) {
        let f = AtomicRefCell::new(f);
        self.event_handlers
            .entry::<EventHandlersOf<E>>()
            .or_default()
            .push(Box::new(move |state, world, index, event| {
                (f.borrow_mut())(EventCtx {
                    state,
                    rule: &mut state.rule_mut(),
                    event,
                    world,
                    index,
                })
            }));
    }

    pub fn data(&self) -> impl Deref<Target = Data> + '_ { self.resource() }

    pub fn data_mut(&self) -> impl DerefMut<Target = Data> + '_ { self.resource_mut() }

    pub fn get_data_mut(&mut self) -> &mut Data { self.get_resource_mut() }

    pub fn resource<R: Send + Sync + 'static>(&self) -> impl Deref<Target = R> + '_ {
        self.resources
            .get::<AtomicRefCell<R>>()
            .unwrap_or_else(|| {
                panic!(
                    "Tried to access resource '{}' but it does not exist",
                    type_name::<R>()
                )
            })
            .borrow()
    }

    pub fn get_resource_mut<R: Send + Sync + 'static>(&mut self) -> &mut R {
        self.resources
            .get_mut::<AtomicRefCell<R>>()
            .unwrap_or_else(|| {
                panic!(
                    "Tried to access resource '{}' but it does not exist",
                    type_name::<R>()
                )
            })
            .get_mut()
    }

    pub fn resource_mut<R: Send + Sync + 'static>(&self) -> impl DerefMut<Target = R> + '_ {
        self.resources
            .get::<AtomicRefCell<R>>()
            .unwrap_or_else(|| {
                panic!(
                    "Tried to access resource '{}' but it does not exist",
                    type_name::<R>()
                )
            })
            .borrow_mut()
    }

    pub fn emit<E: Event>(&mut self, e: E, world: &World, index: IndexRef) {
        // TODO: Queue these events up and handle them on a regular rtsim tick instead
        // of executing their handlers immediately.
        if let Some(handlers) = self.event_handlers.get::<EventHandlersOf<E>>() {
            handlers.iter().for_each(|f| f(self, world, index, &e));
        }
    }

    pub fn tick(
        &mut self,
        world: &World,
        index: IndexRef,
        time_of_day: TimeOfDay,
        time: Time,
        dt: f32,
    ) {
        let tick = {
            let mut data = self.data_mut();
            data.time_of_day = time_of_day;
            data.tick += 1;
            data.tick
        };
        let event = OnTick {
            time_of_day,
            tick,
            time,
            dt,
        };
        self.emit(event, world, index);
    }
}