use crate::time::Duration;
use crate::{fmt, io};
const NSEC_PER_SEC: u64 = 1_000_000_000;
pub const UNIX_EPOCH: SystemTime = SystemTime { t: Timespec::zero() };
#[allow(dead_code)] pub const TIMESPEC_MAX: libc::timespec =
    libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 };
#[cfg(target_os = "nto")]
pub(in crate::sys) const TIMESPEC_MAX_CAPPED: libc::timespec = libc::timespec {
    tv_sec: (u64::MAX / NSEC_PER_SEC) as i64,
    tv_nsec: (u64::MAX % NSEC_PER_SEC) as i64,
};
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(transparent)]
#[rustc_layout_scalar_valid_range_start(0)]
#[rustc_layout_scalar_valid_range_end(999_999_999)]
struct Nanoseconds(u32);
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct SystemTime {
    pub(crate) t: Timespec,
}
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub(crate) struct Timespec {
    tv_sec: i64,
    tv_nsec: Nanoseconds,
}
impl SystemTime {
    #[cfg_attr(any(target_os = "horizon", target_os = "hurd"), allow(unused))]
    pub fn new(tv_sec: i64, tv_nsec: i64) -> Result<SystemTime, io::Error> {
        Ok(SystemTime { t: Timespec::new(tv_sec, tv_nsec)? })
    }
    pub fn now() -> SystemTime {
        SystemTime { t: Timespec::now(libc::CLOCK_REALTIME) }
    }
    pub fn sub_time(&self, other: &SystemTime) -> Result<Duration, Duration> {
        self.t.sub_timespec(&other.t)
    }
    pub fn checked_add_duration(&self, other: &Duration) -> Option<SystemTime> {
        Some(SystemTime { t: self.t.checked_add_duration(other)? })
    }
    pub fn checked_sub_duration(&self, other: &Duration) -> Option<SystemTime> {
        Some(SystemTime { t: self.t.checked_sub_duration(other)? })
    }
}
impl fmt::Debug for SystemTime {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SystemTime")
            .field("tv_sec", &self.t.tv_sec)
            .field("tv_nsec", &self.t.tv_nsec.0)
            .finish()
    }
}
impl Timespec {
    const unsafe fn new_unchecked(tv_sec: i64, tv_nsec: i64) -> Timespec {
        Timespec { tv_sec, tv_nsec: unsafe { Nanoseconds(tv_nsec as u32) } }
    }
    pub const fn zero() -> Timespec {
        unsafe { Self::new_unchecked(0, 0) }
    }
    const fn new(tv_sec: i64, tv_nsec: i64) -> Result<Timespec, io::Error> {
        #[cfg(target_vendor = "apple")]
        let (tv_sec, tv_nsec) =
            if (tv_sec <= 0 && tv_sec > i64::MIN) && (tv_nsec < 0 && tv_nsec > -1_000_000_000) {
                (tv_sec - 1, tv_nsec + 1_000_000_000)
            } else {
                (tv_sec, tv_nsec)
            };
        if tv_nsec >= 0 && tv_nsec < NSEC_PER_SEC as i64 {
            Ok(unsafe { Self::new_unchecked(tv_sec, tv_nsec) })
        } else {
            Err(io::const_io_error!(io::ErrorKind::InvalidData, "Invalid timestamp"))
        }
    }
    pub fn now(clock: libc::clockid_t) -> Timespec {
        use crate::mem::MaybeUninit;
        use crate::sys::cvt;
        #[cfg(all(
            target_os = "linux",
            target_env = "gnu",
            target_pointer_width = "32",
            not(target_arch = "riscv32")
        ))]
        {
            use crate::sys::weak::weak;
            weak!(fn __clock_gettime64(libc::clockid_t, *mut __timespec64) -> libc::c_int);
            if let Some(clock_gettime64) = __clock_gettime64.get() {
                let mut t = MaybeUninit::uninit();
                cvt(unsafe { clock_gettime64(clock, t.as_mut_ptr()) }).unwrap();
                let t = unsafe { t.assume_init() };
                return Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap();
            }
        }
        let mut t = MaybeUninit::uninit();
        cvt(unsafe { libc::clock_gettime(clock, t.as_mut_ptr()) }).unwrap();
        let t = unsafe { t.assume_init() };
        Timespec::new(t.tv_sec as i64, t.tv_nsec as i64).unwrap()
    }
    pub fn sub_timespec(&self, other: &Timespec) -> Result<Duration, Duration> {
        if self >= other {
            let (secs, nsec) = if self.tv_nsec.0 >= other.tv_nsec.0 {
                ((self.tv_sec - other.tv_sec) as u64, self.tv_nsec.0 - other.tv_nsec.0)
            } else {
                (
                    (self.tv_sec - other.tv_sec - 1) as u64,
                    self.tv_nsec.0 + (NSEC_PER_SEC as u32) - other.tv_nsec.0,
                )
            };
            Ok(Duration::new(secs, nsec))
        } else {
            match other.sub_timespec(self) {
                Ok(d) => Err(d),
                Err(d) => Ok(d),
            }
        }
    }
    pub fn checked_add_duration(&self, other: &Duration) -> Option<Timespec> {
        let mut secs = self.tv_sec.checked_add_unsigned(other.as_secs())?;
        let mut nsec = other.subsec_nanos() + self.tv_nsec.0;
        if nsec >= NSEC_PER_SEC as u32 {
            nsec -= NSEC_PER_SEC as u32;
            secs = secs.checked_add(1)?;
        }
        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
    }
    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Timespec> {
        let mut secs = self.tv_sec.checked_sub_unsigned(other.as_secs())?;
        let mut nsec = self.tv_nsec.0 as i32 - other.subsec_nanos() as i32;
        if nsec < 0 {
            nsec += NSEC_PER_SEC as i32;
            secs = secs.checked_sub(1)?;
        }
        Some(unsafe { Timespec::new_unchecked(secs, nsec.into()) })
    }
    #[allow(dead_code)]
    pub fn to_timespec(&self) -> Option<libc::timespec> {
        Some(libc::timespec {
            tv_sec: self.tv_sec.try_into().ok()?,
            tv_nsec: self.tv_nsec.0.try_into().ok()?,
        })
    }
    #[cfg(target_os = "nto")]
    pub(in crate::sys) fn to_timespec_capped(&self) -> Option<libc::timespec> {
        if (self.tv_nsec.0 as u64)
            .checked_add((self.tv_sec as u64).checked_mul(NSEC_PER_SEC)?)
            .is_none()
        {
            return None;
        }
        self.to_timespec()
    }
    #[cfg(all(
        target_os = "linux",
        target_env = "gnu",
        target_pointer_width = "32",
        not(target_arch = "riscv32")
    ))]
    pub fn to_timespec64(&self) -> __timespec64 {
        __timespec64::new(self.tv_sec, self.tv_nsec.0 as _)
    }
}
#[cfg(all(
    target_os = "linux",
    target_env = "gnu",
    target_pointer_width = "32",
    not(target_arch = "riscv32")
))]
#[repr(C)]
pub(crate) struct __timespec64 {
    pub(crate) tv_sec: i64,
    #[cfg(target_endian = "big")]
    _padding: i32,
    pub(crate) tv_nsec: i32,
    #[cfg(target_endian = "little")]
    _padding: i32,
}
#[cfg(all(
    target_os = "linux",
    target_env = "gnu",
    target_pointer_width = "32",
    not(target_arch = "riscv32")
))]
impl __timespec64 {
    pub(crate) fn new(tv_sec: i64, tv_nsec: i32) -> Self {
        Self { tv_sec, tv_nsec, _padding: 0 }
    }
}
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Instant {
    t: Timespec,
}
impl Instant {
    pub fn now() -> Instant {
        #[cfg(target_vendor = "apple")]
        const clock_id: libc::clockid_t = libc::CLOCK_UPTIME_RAW;
        #[cfg(not(target_vendor = "apple"))]
        const clock_id: libc::clockid_t = libc::CLOCK_MONOTONIC;
        Instant { t: Timespec::now(clock_id) }
    }
    pub fn checked_sub_instant(&self, other: &Instant) -> Option<Duration> {
        self.t.sub_timespec(&other.t).ok()
    }
    pub fn checked_add_duration(&self, other: &Duration) -> Option<Instant> {
        Some(Instant { t: self.t.checked_add_duration(other)? })
    }
    pub fn checked_sub_duration(&self, other: &Duration) -> Option<Instant> {
        Some(Instant { t: self.t.checked_sub_duration(other)? })
    }
}
impl fmt::Debug for Instant {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Instant")
            .field("tv_sec", &self.t.tv_sec)
            .field("tv_nsec", &self.t.tv_nsec.0)
            .finish()
    }
}