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    use crate::process::Pid;
    use crate::{backend, io};
    use bitflags::bitflags;

    bitflags! {
        /// Options for modifying the behavior of wait/waitpid
        pub struct WaitOptions: u32 {
            /// Return immediately if no child has exited.
            const NOHANG = backend::process::wait::WNOHANG as _;
            /// Return if a child has stopped (but not traced via `ptrace(2)`)
            const UNTRACED = backend::process::wait::WUNTRACED as _;
            /// Return if a stopped child has been resumed by delivery of `SIGCONT`
            const CONTINUED = backend::process::wait::WCONTINUED as _;
        }
    }

    /// the status of the child processes the caller waited on
    #[derive(Debug, Clone, Copy)]
    pub struct WaitStatus(u32);

    impl WaitStatus {
        /// create a `WaitStatus` out of an integer.
        #[inline]
        pub(crate) fn new(status: u32) -> Self {
            Self(status)
        }

        /// Converts a `WaitStatus` into its raw representation as an integer.
        #[inline]
        pub const fn as_raw(self) -> u32 {
            self.0
        }

        /// Returns whether the process is currently stopped.
        #[inline]
        pub fn stopped(self) -> bool {
            backend::process::wait::WIFSTOPPED(self.0 as _)
        }

        /// Returns whether the process has continued from a job control stop.
        #[inline]
        pub fn continued(self) -> bool {
            backend::process::wait::WIFCONTINUED(self.0 as _)
        }

        /// Returns the number of the signal that stopped the process,
        /// if the process was stopped by a signal.
        #[inline]
        pub fn stopping_signal(self) -> Option<u32> {
            if self.stopped() {
                Some(backend::process::wait::WSTOPSIG(self.0 as _) as _)
            } else {
                None
            }
        }

        /// Returns the exit status number returned by the process,
        /// if it exited normally.
        #[inline]
        pub fn exit_status(self) -> Option<u32> {
            if backend::process::wait::WIFEXITED(self.0 as _) {
                Some(backend::process::wait::WEXITSTATUS(self.0 as _) as _)
            } else {
                None
            }
        }

        /// Returns the number of the signal that terminated the process,
        /// if the process was terminated by a signal.
        #[inline]
        pub fn terminating_signal(self) -> Option<u32> {
            if backend::process::wait::WIFSIGNALED(self.0 as _) {
                Some(backend::process::wait::WTERMSIG(self.0 as _) as _)
            } else {
                None
            }
        }
    }

    /// `waitpid(pid, waitopts)`—Wait for a specific process to change state.
    ///
    /// If the pid is `None`, the call will wait for any child process whose
    /// process group id matches that of the calling process.
    ///
    /// If the pid is equal to `RawPid::MAX`, the call will wait for any child
    /// process.
    ///
    /// Otherwise if the `wrapping_neg` of pid is less than pid, the call will wait
    /// for any child process with a group ID equal to the `wrapping_neg` of `pid`.
    ///
    /// Otherwise, the call will wait for the child process with the given pid.
    ///
    /// On Success, returns the status of the selected process.
    ///
    /// If `NOHANG` was specified in the options, and the selected child process
    /// didn't change state, returns `None`.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html
    /// [Linux]: https://man7.org/linux/man-pages/man2/waitpid.2.html
    #[cfg(not(target_os = "wasi"))]
    #[inline]
    pub fn waitpid(pid: Option<Pid>, waitopts: WaitOptions) -> io::Result<Option<WaitStatus>> {
        Ok(backend::process::syscalls::waitpid(pid, waitopts)?.map(|(_, status)| status))
    }

    /// `wait(waitopts)`—Wait for any of the children of calling process to
    /// change state.
    ///
    /// On success, returns the pid of the child process whose state changed, and
    /// the status of said process.
    ///
    /// If `NOHANG` was specified in the options, and the selected child process
    /// didn't change state, returns `None`.
    ///
    /// # References
    ///  - [POSIX]
    ///  - [Linux]
    ///
    /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/wait.html
    /// [Linux]: https://man7.org/linux/man-pages/man2/waitpid.2.html
    #[cfg(not(target_os = "wasi"))]
    #[inline]
    pub fn wait(waitopts: WaitOptions) -> io::Result<Option<(Pid, WaitStatus)>> {
        backend::process::syscalls::wait(waitopts)
    }