pub use libc::dev_t;
pub use libc::stat as FileStat;

use {Result, NixPath};
use errno::Errno;
use fcntl::AtFlags;
use libc::{self, mode_t};
use std::mem;
use std::os::unix::io::RawFd;

libc_bitflags!(
    pub struct SFlag: mode_t {
        S_IFIFO;
        S_IFCHR;
        S_IFDIR;
        S_IFBLK;
        S_IFREG;
        S_IFLNK;
        S_IFSOCK;
        S_IFMT;
    }
);

libc_bitflags! {
    pub struct Mode: mode_t {
        S_IRWXU;
        S_IRUSR;
        S_IWUSR;
        S_IXUSR;
        S_IRWXG;
        S_IRGRP;
        S_IWGRP;
        S_IXGRP;
        S_IRWXO;
        S_IROTH;
        S_IWOTH;
        S_IXOTH;
        S_ISUID as mode_t;
        S_ISGID as mode_t;
        S_ISVTX as mode_t;
    }
}

pub fn mknod<P: ?Sized + NixPath>(path: &P, kind: SFlag, perm: Mode, dev: dev_t) -> Result<()> {
    let res = try!(path.with_nix_path(|cstr| {
        unsafe {
            libc::mknod(cstr.as_ptr(), kind.bits | perm.bits() as mode_t, dev)
        }
    }));

    Errno::result(res).map(drop)
}

#[cfg(target_os = "linux")]
pub fn major(dev: dev_t) -> u64 {
    ((dev >> 32) & 0xffff_f000) |
    ((dev >>  8) & 0x0000_0fff)
}

#[cfg(target_os = "linux")]
pub fn minor(dev: dev_t) -> u64 {
    ((dev >> 12) & 0xffff_ff00) |
    ((dev      ) & 0x0000_00ff)
}

#[cfg(target_os = "linux")]
pub fn makedev(major: u64, minor: u64) -> dev_t {
    ((major & 0xffff_f000) << 32) |
    ((major & 0x0000_0fff) <<  8) |
    ((minor & 0xffff_ff00) << 12) |
     (minor & 0x0000_00ff)
}

pub fn umask(mode: Mode) -> Mode {
    let prev = unsafe { libc::umask(mode.bits() as mode_t) };
    Mode::from_bits(prev).expect("[BUG] umask returned invalid Mode")
}

pub fn stat<P: ?Sized + NixPath>(path: &P) -> Result<FileStat> {
    let mut dst = unsafe { mem::uninitialized() };
    let res = try!(path.with_nix_path(|cstr| {
        unsafe {
            libc::stat(cstr.as_ptr(), &mut dst as *mut FileStat)
        }
    }));

    try!(Errno::result(res));

    Ok(dst)
}

pub fn lstat<P: ?Sized + NixPath>(path: &P) -> Result<FileStat> {
    let mut dst = unsafe { mem::uninitialized() };
    let res = try!(path.with_nix_path(|cstr| {
        unsafe {
            libc::lstat(cstr.as_ptr(), &mut dst as *mut FileStat)
        }
    }));

    try!(Errno::result(res));

    Ok(dst)
}

pub fn fstat(fd: RawFd) -> Result<FileStat> {
    let mut dst = unsafe { mem::uninitialized() };
    let res = unsafe { libc::fstat(fd, &mut dst as *mut FileStat) };

    try!(Errno::result(res));

    Ok(dst)
}

pub fn fstatat<P: ?Sized + NixPath>(dirfd: RawFd, pathname: &P, f: AtFlags) -> Result<FileStat> {
    let mut dst = unsafe { mem::uninitialized() };
    let res = try!(pathname.with_nix_path(|cstr| {
        unsafe { libc::fstatat(dirfd, cstr.as_ptr(), &mut dst as *mut FileStat, f.bits() as libc::c_int) }
    }));

    try!(Errno::result(res));

    Ok(dst)
}

/// Change the file permission bits of the file specified by a file descriptor.
///
/// # References
///
/// [fchmod(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/fchmod.html).
pub fn fchmod(fd: RawFd, mode: Mode) -> Result<()> {
    let res = unsafe { libc::fchmod(fd, mode.bits() as mode_t) };

    Errno::result(res).map(|_| ())
}

/// Flags for `fchmodat` function.
#[derive(Clone, Copy, Debug)]
pub enum FchmodatFlags {
    FollowSymlink,
    NoFollowSymlink,
}

/// Change the file permission bits.
///
/// The file to be changed is determined relative to the directory associated
/// with the file descriptor `dirfd` or the current working directory
/// if `dirfd` is `None`.
///
/// If `flag` is `FchmodatFlags::NoFollowSymlink` and `path` names a symbolic link,
/// then the mode of the symbolic link is changed.
///
/// `fchmod(None, path, mode, FchmodatFlags::FollowSymlink)` is identical to
/// a call `libc::chmod(path, mode)`. That's why `chmod` is unimplemented
/// in the `nix` crate.
///
/// # References
///
/// [fchmodat(2)](http://pubs.opengroup.org/onlinepubs/9699919799/functions/fchmodat.html).
pub fn fchmodat<P: ?Sized + NixPath>(
    dirfd: Option<RawFd>,
    path: &P,
    mode: Mode,
    flag: FchmodatFlags,
) -> Result<()> {
    let actual_dirfd =
        match dirfd {
            None => libc::AT_FDCWD,
            Some(fd) => fd,
        };
    let atflag =
        match flag {
            FchmodatFlags::FollowSymlink => AtFlags::empty(),
            FchmodatFlags::NoFollowSymlink => AtFlags::AT_SYMLINK_NOFOLLOW,
        };
    let res = path.with_nix_path(|cstr| unsafe {
        libc::fchmodat(
            actual_dirfd,
            cstr.as_ptr(),
            mode.bits() as mode_t,
            atflag.bits() as libc::c_int,
        )
    })?;

    Errno::result(res).map(|_| ())
}