// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Language-level runtime services that should reasonably expected
//! to be available 'everywhere'. Local heaps, GC, unwinding,
//! local storage, and logging. Even a 'freestanding' Rust would likely want
//! to implement this.

use borrow;
use cast::transmute;
use cleanup;
use libc::{c_void, uintptr_t};
use ptr;
use prelude::*;
use option::{Option, Some, None};
use rt::local::Local;
use rt::logging::StdErrLogger;
use super::local_heap::LocalHeap;
use rt::sched::{SchedHome, AnySched};
use rt::join_latch::JoinLatch;

pub struct Task {
    heap: LocalHeap,
    gc: GarbageCollector,
    storage: LocalStorage,
    logger: StdErrLogger,
    unwinder: Unwinder,
    home: Option<SchedHome>,
    join_latch: Option<~JoinLatch>,
    on_exit: Option<~fn(bool)>,
    destroyed: bool
}

pub struct GarbageCollector;
pub struct LocalStorage(*c_void, Option<~fn(*c_void)>);

pub struct Unwinder {
    unwinding: bool,
}

impl Task {
    pub fn new_root() -> Task {
        Task {
            heap: LocalHeap::new(),
            gc: GarbageCollector,
            storage: LocalStorage(ptr::null(), None),
            logger: StdErrLogger,
            unwinder: Unwinder { unwinding: false },
            home: Some(AnySched),
            join_latch: Some(JoinLatch::new_root()),
            on_exit: None,
            destroyed: false
        }
    }

    pub fn new_child(&mut self) -> Task {
        Task {
            heap: LocalHeap::new(),
            gc: GarbageCollector,
            storage: LocalStorage(ptr::null(), None),
            logger: StdErrLogger,
            home: Some(AnySched),
            unwinder: Unwinder { unwinding: false },
            join_latch: Some(self.join_latch.get_mut_ref().new_child()),
            on_exit: None,
            destroyed: false
        }
    }

    pub fn give_home(&mut self, new_home: SchedHome) {
        self.home = Some(new_home);
    }

    pub fn run(&mut self, f: &fn()) {
        // This is just an assertion that `run` was called unsafely
        // and this instance of Task is still accessible.
        do Local::borrow::<Task, ()> |task| {
            assert!(borrow::ref_eq(task, self));
        }

        self.unwinder.try(f);
        self.destroy();

        // Wait for children. Possibly report the exit status.
        let local_success = !self.unwinder.unwinding;
        let join_latch = self.join_latch.swap_unwrap();
        match self.on_exit {
            Some(ref on_exit) => {
                let success = join_latch.wait(local_success);
                (*on_exit)(success);
            }
            None => {
                join_latch.release(local_success);
            }
        }
    }

    /// must be called manually before finalization to clean up
    /// thread-local resources. Some of the routines here expect
    /// Task to be available recursively so this must be
    /// called unsafely, without removing Task from
    /// thread-local-storage.
    fn destroy(&mut self) {
        // This is just an assertion that `destroy` was called unsafely
        // and this instance of Task is still accessible.
        do Local::borrow::<Task, ()> |task| {
            assert!(borrow::ref_eq(task, self));
        }
        match self.storage {
            LocalStorage(ptr, Some(ref dtor)) => {
                (*dtor)(ptr)
            }
            _ => ()
        }

        // Destroy remaining boxes
        unsafe { cleanup::annihilate(); }

        self.destroyed = true;
    }
}

impl Drop for Task {
    fn finalize(&self) { assert!(self.destroyed) }
}

// Just a sanity check to make sure we are catching a Rust-thrown exception
static UNWIND_TOKEN: uintptr_t = 839147;

impl Unwinder {
    pub fn try(&mut self, f: &fn()) {
        use sys::Closure;

        unsafe {
            let closure: Closure = transmute(f);
            let code = transmute(closure.code);
            let env = transmute(closure.env);

            let token = rust_try(try_fn, code, env);
            assert!(token == 0 || token == UNWIND_TOKEN);
        }

        extern fn try_fn(code: *c_void, env: *c_void) {
            unsafe {
                let closure: Closure = Closure {
                    code: transmute(code),
                    env: transmute(env),
                };
                let closure: &fn() = transmute(closure);
                closure();
            }
        }

        extern {
            #[rust_stack]
            fn rust_try(f: *u8, code: *c_void, data: *c_void) -> uintptr_t;
        }
    }

    pub fn begin_unwind(&mut self) -> ! {
        self.unwinding = true;
        unsafe {
            rust_begin_unwind(UNWIND_TOKEN);
            return transmute(());
        }
        extern {
            fn rust_begin_unwind(token: uintptr_t);
        }
    }
}

#[cfg(test)]
mod test {
    use rt::test::*;

    #[test]
    fn local_heap() {
        do run_in_newsched_task() {
            let a = @5;
            let b = a;
            assert!(*a == 5);
            assert!(*b == 5);
        }
    }

    #[test]
    fn tls() {
        use local_data::*;
        do run_in_newsched_task() {
            unsafe {
                fn key(_x: @~str) { }
                local_data_set(key, @~"data");
                assert!(*local_data_get(key).get() == ~"data");
                fn key2(_x: @~str) { }
                local_data_set(key2, @~"data");
                assert!(*local_data_get(key2).get() == ~"data");
            }
        }
    }

    #[test]
    fn unwind() {
        do run_in_newsched_task() {
            let result = spawntask_try(||());
            assert!(result.is_ok());
            let result = spawntask_try(|| fail!());
            assert!(result.is_err());
        }
    }

    #[test]
    fn rng() {
        do run_in_newsched_task() {
            use rand::{rng, Rng};
            let mut r = rng();
            let _ = r.next();
        }
    }

    #[test]
    fn logging() {
        do run_in_newsched_task() {
            info!("here i am. logging in a newsched task");
        }
    }

    #[test]
    fn comm_oneshot() {
        use comm::*;

        do run_in_newsched_task {
            let (port, chan) = oneshot();
            send_one(chan, 10);
            assert!(recv_one(port) == 10);
        }
    }

    #[test]
    fn comm_stream() {
        use comm::*;

        do run_in_newsched_task() {
            let (port, chan) = stream();
            chan.send(10);
            assert!(port.recv() == 10);
        }
    }

    #[test]
    fn comm_shared_chan() {
        use comm::*;

        do run_in_newsched_task() {
            let (port, chan) = stream();
            let chan = SharedChan::new(chan);
            chan.send(10);
            assert!(port.recv() == 10);
        }
    }

    #[test]
    fn linked_failure() {
        do run_in_newsched_task() {
            let res = do spawntask_try {
                spawntask_random(|| fail!());
            };
            assert!(res.is_err());
        }
    }

    #[test]
    fn heap_cycles() {
        use option::{Option, Some, None};

        do run_in_newsched_task {
            struct List {
                next: Option<@mut List>,
            }

            let a = @mut List { next: None };
            let b = @mut List { next: Some(a) };

            a.next = Some(b);
        }
    }
}