use fortanix_sgx_abi::Fd;

use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
use crate::mem::ManuallyDrop;
use crate::sys::pal::abi::usercalls;
use crate::sys::{AsInner, FromInner, IntoInner};

#[derive(Debug)]
pub struct FileDesc {
    fd: Fd,
}

impl FileDesc {
    pub fn new(fd: Fd) -> FileDesc {
        FileDesc { fd }
    }

    pub fn raw(&self) -> Fd {
        self.fd
    }

    /// Extracts the actual file descriptor without closing it.
    pub fn into_raw(self) -> Fd {
        ManuallyDrop::new(self).fd
    }

    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
        usercalls::read(self.fd, &mut [IoSliceMut::new(buf)])
    }

    pub fn read_buf(&self, buf: BorrowedCursor<'_, u8>) -> io::Result<()> {
        usercalls::read_buf(self.fd, buf)
    }

    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
        usercalls::read(self.fd, bufs)
    }

    #[inline]
    pub fn is_read_vectored(&self) -> bool {
        true
    }

    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
        usercalls::write(self.fd, &[IoSlice::new(buf)])
    }

    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
        usercalls::write(self.fd, bufs)
    }

    #[inline]
    pub fn is_write_vectored(&self) -> bool {
        true
    }

    pub fn flush(&self) -> io::Result<()> {
        usercalls::flush(self.fd)
    }
}

impl AsInner<Fd> for FileDesc {
    #[inline]
    fn as_inner(&self) -> &Fd {
        &self.fd
    }
}

impl IntoInner<Fd> for FileDesc {
    fn into_inner(self) -> Fd {
        ManuallyDrop::new(self).fd
    }
}

impl FromInner<Fd> for FileDesc {
    fn from_inner(fd: Fd) -> FileDesc {
        FileDesc { fd }
    }
}

impl Drop for FileDesc {
    fn drop(&mut self) {
        usercalls::close(self.fd)
    }
}