use once_spin::*;
use std::{
    mem::forget,
    sync::{
        atomic::{AtomicUsize, Ordering},
        mpsc::channel,
        Arc,
    },
    thread,
};

#[derive(Eq, PartialEq, Debug)]
struct NonCopy(i32);

#[test]
fn smoke() {
    let m = Mutex::new(());
    drop(m.lock());
    drop(m.lock());
}

#[test]
fn lots_and_lots() {
    static M: Mutex<()> = Mutex::new(());
    static mut CNT: u32 = 0;
    const J: u32 = 1000;
    const K: u32 = 3;

    fn inc() {
        for _ in 0..J {
            unsafe {
                let _g = M.lock();
                CNT += 1;
            }
        }
    }

    let (tx, rx) = channel();
    for _ in 0..K {
        let tx2 = tx.clone();
        thread::spawn(move || {
            inc();
            tx2.send(()).unwrap();
        });
        let tx2 = tx.clone();
        thread::spawn(move || {
            inc();
            tx2.send(()).unwrap();
        });
    }

    drop(tx);
    for _ in 0..2 * K {
        rx.recv().unwrap();
    }
    assert_eq!(unsafe { CNT }, J * K * 2);
}

#[test]
fn try_lock() {
    let mutex = Mutex::new(42);

    let a = mutex.try_lock();
    assert_eq!(a.as_ref().map(|r| **r), Some(42));

    let b = mutex.try_lock();
    assert!(b.is_none());

    drop(a);
    let c = mutex.try_lock();
    assert_eq!(c.as_ref().map(|r| **r), Some(42));
}

#[test]
fn test_into_inner() {
    let m = Mutex::new(NonCopy(10));
    assert_eq!(m.into_inner(), NonCopy(10));
}

#[test]
fn test_into_inner_drop() {
    struct Foo(Arc<AtomicUsize>);

    impl Drop for Foo {
        fn drop(&mut self) {
            self.0.fetch_add(1, Ordering::SeqCst);
        }
    }

    let num_drops = Arc::new(AtomicUsize::new(0));
    let m = Mutex::new(Foo(num_drops.clone()));
    assert_eq!(num_drops.load(Ordering::SeqCst), 0);
    {
        let _inner = m.into_inner();
        assert_eq!(num_drops.load(Ordering::SeqCst), 0);
    }
    assert_eq!(num_drops.load(Ordering::SeqCst), 1);
}

#[test]
fn test_mutex_arc_nested() {
    let arc = Arc::new(Mutex::new(1));
    let arc2 = Arc::new(Mutex::new(arc));
    let (tx, rx) = channel();
    let _t = thread::spawn(move || {
        let lock = arc2.lock();
        let lock2 = lock.lock();
        assert_eq!(*lock2, 1);
        tx.send(()).unwrap();
    });
    rx.recv().unwrap();
}

#[test]
fn test_mutex_arc_access_in_unwind() {
    let arc = Arc::new(Mutex::new(1));
    let arc2 = arc.clone();
    let _ = thread::spawn(move || -> () {
        struct Unwinder {
            i: Arc<Mutex<i32>>,
        }

        impl Drop for Unwinder {
            fn drop(&mut self) {
                *self.i.lock() += 1;
            }
        }

        let _u = Unwinder { i: arc2 };
        panic!();
    })
    .join();
    let lock = arc.lock();
    assert_eq!(*lock, 2);
}

#[test]
fn test_mutex_unsized() {
    let mutex: &Mutex<[i32]> = &Mutex::new([1, 2, 3]);
    {
        let b = &mut *mutex.lock();
        b[0] = 4;
        b[2] = 5;
    }
    let comp: &[i32] = &[4, 2, 5];
    assert_eq!(&*mutex.lock(), comp);
}

#[test]
fn test_mutex_force_lock() {
    let lock = Mutex::new(());
    forget(lock.lock());
    unsafe {
        lock.force_unlock();
    }
    assert!(lock.try_lock().is_some());
}