#![allow(dead_code)]

extern crate libc;

use libc::{c_int, c_void, time_t, timespec};
use std::io;
use std::os::unix::io::{AsRawFd, RawFd};
use std::time::Duration;

/*
 * libc timer implementation
 */
#[allow(non_camel_case_types)]
#[repr(C)]
struct itimerspec {
    it_interval: timespec,
    it_value: timespec,
}

#[allow(non_camel_case_types)]
pub struct Itimerspec {
    pub it_interval: Duration,
    pub it_value: Duration,
}

extern "C" {
    fn timerfd_create(clockid: c_int, flags: c_int) -> RawFd;
    fn timerfd_settime(
        fd: RawFd,
        flags: c_int,
        new_value: *const itimerspec,
        old_value: *mut itimerspec,
    ) -> libc::c_int;
    fn timerfd_gettime(fd: RawFd, curr_value: *mut itimerspec) -> libc::c_int;
}

pub struct Timerfd(RawFd);

impl Timerfd {
    pub fn create(clockid: c_int, flags: c_int) -> io::Result<Self> {
        let timerfd = unsafe { timerfd_create(clockid, flags) };
        if timerfd == -1 {
            return Err(io::Error::last_os_error());
        }
        Ok(Timerfd(timerfd))
    }

    pub fn settime(&self, flags: c_int, new_value: &Itimerspec) -> io::Result<Itimerspec> {
        let new_raw = itimerspec {
            it_interval: timespec {
                tv_sec: new_value.it_interval.as_secs() as time_t,
                tv_nsec: new_value.it_interval.subsec_nanos() as i64,
            },
            it_value: timespec {
                tv_sec: new_value.it_value.as_secs() as time_t,
                tv_nsec: new_value.it_value.subsec_nanos() as i64,
            },
        };
        let mut old_raw = itimerspec {
            it_interval: timespec {
                tv_sec: 0,
                tv_nsec: 0,
            },
            it_value: timespec {
                tv_sec: 0,
                tv_nsec: 0,
            },
        };

        if unsafe { timerfd_settime(self.0, flags, &new_raw, &mut old_raw) } == -1 {
            return Err(io::Error::last_os_error());
        }
        Ok(Itimerspec {
            it_interval: Duration::new(
                old_raw.it_interval.tv_sec as u64,
                old_raw.it_interval.tv_nsec as u32,
            ),
            it_value: Duration::new(
                old_raw.it_value.tv_sec as u64,
                old_raw.it_value.tv_nsec as u32,
            ),
        })
    }

    pub fn gettime(&self) -> io::Result<Itimerspec> {
        let mut raw = itimerspec {
            it_interval: timespec {
                tv_sec: 0,
                tv_nsec: 0,
            },
            it_value: timespec {
                tv_sec: 0,
                tv_nsec: 0,
            },
        };
        if unsafe { timerfd_gettime(self.0, &mut raw) } == -1 {
            return Err(io::Error::last_os_error());
        }

        Ok(Itimerspec {
            it_interval: Duration::new(
                raw.it_interval.tv_sec as u64,
                raw.it_interval.tv_nsec as u32,
            ),
            it_value: Duration::new(raw.it_value.tv_sec as u64, raw.it_value.tv_nsec as u32),
        })
    }

    pub fn read(&self) -> io::Result<u64> {
        let mut buf = 0u64;
        let nr = unsafe {
            libc::read(
                self.0,
                &mut buf as *mut _ as *mut c_void,
                ::std::mem::size_of::<u64>(),
            )
        };
        if nr == ::std::mem::size_of::<u64>() as isize {
            return Ok(buf);
        }
        Err(io::Error::last_os_error())
    }
}

impl Drop for Timerfd {
    fn drop(&mut self) {
        unsafe { libc::close(self.0) };
    }
}

impl AsRawFd for Timerfd {
    fn as_raw_fd(&self) -> RawFd {
        self.0
    }
}

/*
 * mio Evented implementation
 */
extern crate mio;
use mio::unix::SourceFd;
use mio::{event, Interest, Registry, Token};

impl event::Source for Timerfd {
    fn register(
        &mut self,
        registry: &Registry,
        token: Token,
        interests: Interest,
    ) -> io::Result<()> {
        SourceFd(&self.0).register(registry, token, interests)
    }

    fn reregister(
        &mut self,
        registry: &Registry,
        token: Token,
        interests: Interest,
    ) -> io::Result<()> {
        SourceFd(&self.0).reregister(registry, token, interests)
    }

    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
        SourceFd(&self.0).deregister(registry)
    }
}

fn main() {}