// vtest retry: 3
// vtest flaky: true
module sync

import time
import sync.stdatomic

fn issue_6870_worker(mut wg WaitGroup, ready chan bool, release chan bool) {
    ready <- true
    _ = <-release
    wg.add(1)
    wg.done()
    wg.done()
}

fn test_waitgroup_reuse() {
    mut wg := new_waitgroup()

    wg.add(1)
    wg.done()

    wg.add(1)
    mut executed := false
    spawn fn (mut wg WaitGroup, executed voidptr) {
        defer {
            wg.done()
        }
        unsafe {
            *(&bool(executed)) = true
        }
        time.sleep(100 * time.millisecond)
    }(mut wg, voidptr(&executed))

    wg.wait()
    assert executed
}

fn test_waitgroup_no_use() {
    done := chan bool{cap: 1}
    watchdog := spawn fn (done chan bool) {
        select {
            _ := <-done {}
            10 * time.second {
                panic('test_waitgroup_no_use did not complete in time')
            }
        }
    }(done)

    mut wg := new_waitgroup()
    wg.wait()
    done <- true
    watchdog.wait()
}

fn test_waitgroup_go() {
    mut counter := stdatomic.new_atomic(0)
    mut wg := new_waitgroup()
    for i in 0 .. 10 {
        wg.go(fn [mut counter] () {
            counter.add(1)
        })
    }
    wg.wait()
    assert counter.load() == 10
}

fn test_waitgroup_add_while_waiting() {
    for _ in 0 .. 50 {
        mut wg := new_waitgroup()
        ready := chan bool{cap: 1}
        release := chan bool{cap: 1}
        wait_done := chan bool{cap: 8}
        wg.add(1)

        spawn issue_6870_worker(mut wg, ready, release)
        _ = <-ready

        for _ in 0 .. 8 {
            spawn fn [mut wg, wait_done] () {
                wg.wait()
                wait_done <- true
            }()
        }
        release <- true

        for _ in 0 .. 8 {
            select {
                _ := <-wait_done {}
                2 * time.second {
                    assert false, 'wait() missed a wakeup while work added more tasks'
                }
            }
        }
    }
}