use safina::threadpool::{NewThreadPoolError, ThreadPool, TryScheduleError, INTERNAL_MAX_THREADS};
use std::ops::Range;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::time::{Duration, Instant};

static LOCK: std::sync::Mutex<()> = std::sync::Mutex::new(());

fn assert_elapsed(before: Instant, range_ms: Range<u64>) {
    assert!(!range_ms.is_empty(), "invalid range {:?}", range_ms);
    let elapsed = before.elapsed();
    println!("elapsed = {} ms", elapsed.as_millis());
    let duration_range = Duration::from_millis(range_ms.start)..Duration::from_millis(range_ms.end);
    assert!(
        duration_range.contains(&elapsed),
        "{:?} elapsed, out of range {:?}",
        elapsed,
        duration_range
    );
}

fn set_max_threads(n: usize) {
    println!("set_max_threads({n})");
    INTERNAL_MAX_THREADS.store(n, Ordering::Release);
}

fn sleep_ms(ms: u64) {
    std::thread::sleep(Duration::from_millis(ms));
}

fn panic_threads(pool: &ThreadPool, num: usize) {
    let pause = Arc::new(AtomicBool::new(true));
    for _ in 0..num {
        let pause_clone = pause.clone();
        pool.try_schedule(move || {
            println!(
                "thread {:?} waiting",
                std::thread::current().name().unwrap_or("")
            );
            while pause_clone.load(Ordering::Acquire) {
                sleep_ms(10);
            }
            println!(
                "panicking thread {:?}",
                std::thread::current().name().unwrap_or("")
            );
            panic!("ignore this panic");
        })
        .unwrap();
    }
    sleep_ms(100);
    pause.store(false, Ordering::Release);
    sleep_ms(100);
}

#[test]
fn new_thread_pool_at_max() {
    let _guard = LOCK.lock().unwrap();
    set_max_threads(2);
    ThreadPool::new("test", 2).unwrap();
}

#[test]
fn new_thread_pool_error_spawn() {
    let _guard = LOCK.lock().unwrap();
    set_max_threads(2);
    let err = ThreadPool::new("test", 3).unwrap_err();
    assert!(matches!(err, NewThreadPoolError::Spawn(_)));
}

#[test]
fn schedule_retries_thread_start() {
    let _guard = LOCK.lock().unwrap();
    set_max_threads(3);
    let pool = ThreadPool::new("test", 3).unwrap();
    panic_threads(&pool, 3);
    set_max_threads(0);
    let before = Instant::now();
    std::thread::spawn(|| {
        sleep_ms(100);
        set_max_threads(1);
    });
    let (sender, receiver) = std::sync::mpsc::channel();
    pool.schedule(move || {
        println!("sending ()");
        sender.send(()).unwrap();
    });
    receiver.recv_timeout(Duration::from_millis(500)).unwrap();
    assert_elapsed(before, 100..200);
}

// schedule_retries_when_queue_full is in tests/test.rs .

// try_schedule_queue_full is in tests/test.rs .

#[test]
fn try_schedule_no_threads() {
    let _guard = LOCK.lock().unwrap();
    set_max_threads(2);
    let pool = ThreadPool::new("test", 2).unwrap();
    panic_threads(&pool, 2);
    set_max_threads(0);
    let result = pool.try_schedule(|| {});
    assert!(
        matches!(result, Err(TryScheduleError::NoThreads(_))),
        "{:?}",
        result
    );
}

#[test]
fn try_schedule_respawn() {
    let _guard = LOCK.lock().unwrap();
    set_max_threads(2);
    let pool = ThreadPool::new("test", 2).unwrap();
    panic_threads(&pool, 1);
    set_max_threads(1);
    let result = pool.try_schedule(|| {});
    assert!(
        matches!(result, Err(TryScheduleError::Respawn(_))),
        "{:?}",
        result
    );
}

#[test]
fn threads_stop_after_pool_drops() {
    let _guard = LOCK.lock().unwrap();
    set_max_threads(2);
    let pool = ThreadPool::new("test", 2).unwrap();
    let num_live_threads_fn = pool.num_live_threads_fn();
    drop(pool);
    std::thread::sleep(Duration::from_millis(100));
    assert_eq!(0, num_live_threads_fn());
}