use std;
use std::thread;
use std::cell::RefCell;
use uuid::Uuid;
use tokio_core::reactor::{Core, Handle};
use futures::sync::oneshot::{channel, Sender};

use actor::{Actor, Handler, AsyncContext};
use address::{Address, SyncAddress};
use context::Context;
use msgs::{Execute, StartActor, StopArbiter};
use message::Response;
use registry::{Registry, SystemRegistry};
use system::{System, RegisterArbiter, UnregisterArbiter};
use queue::sync;

thread_local!(
    static HND: RefCell<Option<Handle>> = RefCell::new(None);
    static STOP: RefCell<Option<Sender<i32>>> = RefCell::new(None);
    static ADDR: RefCell<Option<Address<Arbiter>>> = RefCell::new(None);
    static REG: RefCell<Option<Registry>> = RefCell::new(None);
    static NAME: RefCell<Option<String>> = RefCell::new(None);
    static SYS: RefCell<Option<SyncAddress<System>>> = RefCell::new(None);
    static SYSARB: RefCell<Option<SyncAddress<Arbiter>>> = RefCell::new(None);
    static SYSNAME: RefCell<Option<String>> = RefCell::new(None);
    static SYSREG: RefCell<Option<SystemRegistry>> = RefCell::new(None);
);

/// Event loop controller
///
/// Arbiter controls event loop in it's thread. Each arbiter runs in separate
/// thread. Arbiter provides several api for event loop acces. Each arbiter
/// can belongs to specific `System` actor.
pub struct Arbiter {
    id: Uuid,
    sys: bool,
}


impl Actor for Arbiter {
    type Context = Context<Self>;

    fn started(&mut self, ctx: &mut Context<Self>) {
        // register arbiter within system
        Arbiter::system().send(
            RegisterArbiter(self.id.simple().to_string(), ctx.address()));
    }
}

impl Arbiter {

    /// Spawn new thread and run event loop in spawned thread.
    /// Returns address of newly created arbiter.
    pub fn new<T: ToString>(name: T) -> SyncAddress<Arbiter> {
        let (tx, rx) = std::sync::mpsc::channel();

        let id = Uuid::new_v4();
        let sys = Arbiter::system();
        let sys_name = Arbiter::system_name();
        let sys_arbiter = Arbiter::system_arbiter();
        let sys_registry = Arbiter::system_registry().clone();
        let name =
            format!("arbiter:{:?}:{:?}", id.hyphenated().to_string(), name.to_string());

        let _ = thread::Builder::new().name(name.clone()).spawn(move|| {
            let mut core = Core::new().unwrap();

            let (stop_tx, stop_rx) = channel();
            HND.with(|cell| *cell.borrow_mut() = Some(core.handle()));
            STOP.with(|cell| *cell.borrow_mut() = Some(stop_tx));
            NAME.with(|cell| *cell.borrow_mut() = Some(name));

            // system
            SYS.with(|cell| *cell.borrow_mut() = Some(sys));
            SYSARB.with(|cell| *cell.borrow_mut() = Some(sys_arbiter));
            SYSNAME.with(|cell| *cell.borrow_mut() = Some(sys_name));
            SYSREG.with(|cell| *cell.borrow_mut() = Some(sys_registry));

            // start arbiter
            let (addr, saddr) = Actor::start(
                Arbiter {sys: false, id: id});
            ADDR.with(|cell| *cell.borrow_mut() = Some(addr));

            if tx.send(saddr).is_err() {
                error!("Can not start Arbiter, remote side is dead");
            } else {
                // run loop
                let _ = match core.run(stop_rx) {
                    Ok(code) => code,
                    Err(_) => 1,
                };
            }

            // unregister arbiter
            Arbiter::system().send(
                UnregisterArbiter(id.simple().to_string()));
        });

        rx.recv().unwrap()
    }

    pub(crate) fn new_system(name: String) -> Core {
        let core = Core::new().unwrap();
        HND.with(|cell| *cell.borrow_mut() = Some(core.handle()));
        REG.with(|cell| *cell.borrow_mut() = Some(Registry::new()));
        NAME.with(|cell| *cell.borrow_mut() = Some(name));
        SYSREG.with(|cell| *cell.borrow_mut() = Some(SystemRegistry::new()));

        // start arbiter
        let (addr, sys_addr) = Actor::start(
            Arbiter {sys: true, id: Uuid::new_v4()});
        ADDR.with(|cell| *cell.borrow_mut() = Some(addr));
        SYSARB.with(|cell| *cell.borrow_mut() = Some(sys_addr));

        core
    }

    pub(crate) fn set_system(addr: SyncAddress<System>, name: String) {
        SYS.with(|cell| *cell.borrow_mut() = Some(addr));
        SYSNAME.with(|cell| *cell.borrow_mut() = Some(name));
    }

    /// Returns current arbiter's address
    pub fn name() -> String {
        NAME.with(|cell| match *cell.borrow() {
            Some(ref name) => name.clone(),
            None => panic!("Arbiter is not running"),
        })
    }

    /// Returns current arbiter's address
    pub fn arbiter() -> Address<Arbiter> {
        ADDR.with(|cell| match *cell.borrow() {
            Some(ref addr) => addr.clone(),
            None => panic!("Arbiter is not running"),
        })
    }

    /// This function returns system address,
    pub fn system() -> SyncAddress<System> {
        SYS.with(|cell| match *cell.borrow() {
            Some(ref addr) => addr.clone(),
            None => panic!("System is not running"),
        })
    }

    /// This function returns system address,
    pub fn system_arbiter() -> SyncAddress<Arbiter> {
        SYSARB.with(|cell| match *cell.borrow() {
            Some(ref addr) => addr.clone(),
            None => panic!("System is not running"),
        })
    }

    /// This function returns system name,
    pub fn system_name() -> String {
        SYSNAME.with(|cell| match *cell.borrow() {
            Some(ref name) => name.clone(),
            None => panic!("System is not running"),
        })
    }

    /// This function returns system registry,
    pub fn system_registry() -> &'static SystemRegistry {
        SYSREG.with(|cell| match *cell.borrow() {
            Some(ref reg) => unsafe{std::mem::transmute(reg)},
            None => panic!("System is not running"),
        })
    }

    /// This function returns current event loop's handle,
    pub fn handle() -> &'static Handle {
        HND.with(|cell| match *cell.borrow() {
            Some(ref h) => unsafe{std::mem::transmute(h)},
            None => panic!("Arbiter is not running"),
        })
    }

    /// This function returns arbiter's registry,
    pub fn registry() -> &'static Registry {
        REG.with(|cell| match *cell.borrow() {
            Some(ref reg) => unsafe{std::mem::transmute(reg)},
            None => panic!("System is not running"),
        })
    }

    /// Start new arbiter and then start actor in created arbiter.
    /// Returns `SyncAddress` of created actor.
    pub fn start<A, F>(f: F) -> SyncAddress<A>
        where A: Actor<Context=Context<A>>,
              F: FnOnce(&mut A::Context) -> A + Send + 'static
    {
        let (stx, srx) = sync::unbounded();

        // new arbiter
        let addr = Arbiter::new("actor");

        // create actor
        addr.send::<Execute>(
            Execute::new(move || {
                let mut ctx = Context::with_receiver(
                    unsafe{std::mem::uninitialized()}, srx);
                let act = f(&mut ctx);
                let old = ctx.replace_actor(act);
                std::mem::forget(old);
                ctx.run(Arbiter::handle());
                Ok(())
            }));

        SyncAddress::new(stx)
    }
}

impl Handler<StopArbiter> for Arbiter {

    fn handle(&mut self, msg: StopArbiter, _: &mut Context<Self>) -> Response<Self, StopArbiter>
    {
        if self.sys {
            warn!("System arbiter received `StopArbiter` message.
                  To shutdown system `SystemExit` message should be send to `Address<System>`");
        } else {
            STOP.with(|cell| {
                if let Some(stop) = cell.borrow_mut().take() {
                    let _ = stop.send(msg.0);
                }
            });
        }
        Self::empty()
    }
}

impl<A> Handler<StartActor<A>> for Arbiter where A: Actor<Context=Context<A>> {

    fn handle(&mut self, msg: StartActor<A>, _: &mut Context<Self>) -> Response<Self, StartActor<A>>
    {
        Self::reply(msg.call())
    }
}

/// Execute function in arbiter's thread
impl<I: Send, E: Send> Handler<Execute<I, E>> for Arbiter {

    fn handle(&mut self, msg: Execute<I, E>, _: &mut Context<Self>)
              -> Response<Self, Execute<I, E>>
    {
        match msg.exec() {
            Ok(i) => Self::reply(i),
            Err(e) => Self::reply_error(e),
        }
    }
}