/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

//! This module contains the `EventLoop` type, which is the constellation's
//! view of a script thread. When an `EventLoop` is dropped, an `ExitScriptThread`
//! message is sent to the script thread, asking it to shut down.

use ipc_channel::ipc::IpcSender;
use ipc_channel::Error;
use script_traits::ConstellationControlMsg;
use std::marker::PhantomData;
use std::rc::Rc;

/// <https://html.spec.whatwg.org/multipage/#event-loop>
pub struct EventLoop {
    script_chan: IpcSender<ConstellationControlMsg>,
    dont_send_or_sync: PhantomData<Rc<()>>,
}

impl Drop for EventLoop {
    fn drop(&mut self) {
        let _ = self
            .script_chan
            .send(ConstellationControlMsg::ExitScriptThread);
    }
}

impl EventLoop {
    /// Create a new event loop from the channel to its script thread.
    pub fn new(script_chan: IpcSender<ConstellationControlMsg>) -> Rc<EventLoop> {
        Rc::new(EventLoop {
            script_chan: script_chan,
            dont_send_or_sync: PhantomData,
        })
    }

    /// Send a message to the event loop.
    pub fn send(&self, msg: ConstellationControlMsg) -> Result<(), Error> {
        self.script_chan.send(msg)
    }

    /// The underlying channel to the script thread.
    pub fn sender(&self) -> IpcSender<ConstellationControlMsg> {
        self.script_chan.clone()
    }
}