use nix::fcntl::{openat, open, OFlag, readlink, readlinkat};
use nix::sys::stat::Mode;
use nix::unistd::{close, read};
use tempfile::{self, NamedTempFile};
use std::io::prelude::*;
use std::os::unix::fs;

#[test]
fn test_openat() {
    const CONTENTS: &[u8] = b"abcd";
    let mut tmp = NamedTempFile::new().unwrap();
    tmp.write_all(CONTENTS).unwrap();

    let dirfd = open(tmp.path().parent().unwrap(),
                     OFlag::empty(),
                     Mode::empty()).unwrap();
    let fd = openat(dirfd,
                    tmp.path().file_name().unwrap(),
                    OFlag::O_RDONLY,
                    Mode::empty()).unwrap();

    let mut buf = [0u8; 1024];
    assert_eq!(4, read(fd, &mut buf).unwrap());
    assert_eq!(CONTENTS, &buf[0..4]);

    close(fd).unwrap();
    close(dirfd).unwrap();
}

#[test]
fn test_readlink() {
    let tempdir = tempfile::tempdir().unwrap();
    let src = tempdir.path().join("a");
    let dst = tempdir.path().join("b");
    println!("a: {:?}, b: {:?}", &src, &dst);
    fs::symlink(&src.as_path(), &dst.as_path()).unwrap();
    let dirfd = open(tempdir.path(),
                     OFlag::empty(),
                     Mode::empty()).unwrap();

    let mut buf = vec![0; src.to_str().unwrap().len() + 1];
    assert_eq!(readlink(&dst, &mut buf).unwrap().to_str().unwrap(),
               src.to_str().unwrap());
    assert_eq!(readlinkat(dirfd, "b", &mut buf).unwrap().to_str().unwrap(),
               src.to_str().unwrap());
}

#[cfg(any(target_os = "linux", target_os = "android"))]
mod linux_android {
    use std::io::prelude::*;
    use std::io::SeekFrom;
    use std::os::unix::prelude::*;

    use libc::loff_t;

    use nix::fcntl::*;
    use nix::sys::uio::IoVec;
    use nix::unistd::{close, pipe, read, write};

    use tempfile::{tempfile, NamedTempFile};

    /// This test creates a temporary file containing the contents
    /// 'foobarbaz' and uses the `copy_file_range` call to transfer
    /// 3 bytes at offset 3 (`bar`) to another empty file at offset 0. The
    /// resulting file is read and should contain the contents `bar`.
    /// The from_offset should be updated by the call to reflect
    /// the 3 bytes read (6).
    ///
    /// FIXME: This test is disabled for linux based builds, because Travis
    /// Linux version is too old for `copy_file_range`.
    #[test]
    #[ignore]
    fn test_copy_file_range() {
        const CONTENTS: &[u8] = b"foobarbaz";

        let mut tmp1 = tempfile().unwrap();
        let mut tmp2 = tempfile().unwrap();

        tmp1.write_all(CONTENTS).unwrap();
        tmp1.flush().unwrap();

        let mut from_offset: i64 = 3;
        copy_file_range(
            tmp1.as_raw_fd(),
            Some(&mut from_offset),
            tmp2.as_raw_fd(),
            None,
            3,
        )
        .unwrap();

        let mut res: String = String::new();
        tmp2.seek(SeekFrom::Start(0)).unwrap();
        tmp2.read_to_string(&mut res).unwrap();

        assert_eq!(res, String::from("bar"));
        assert_eq!(from_offset, 6);
    }

    #[test]
    fn test_splice() {
        const CONTENTS: &[u8] = b"abcdef123456";
        let mut tmp = tempfile().unwrap();
        tmp.write_all(CONTENTS).unwrap();

        let (rd, wr) = pipe().unwrap();
        let mut offset: loff_t = 5;
        let res = splice(tmp.as_raw_fd(), Some(&mut offset),
            wr, None, 2, SpliceFFlags::empty()).unwrap();

        assert_eq!(2, res);

        let mut buf = [0u8; 1024];
        assert_eq!(2, read(rd, &mut buf).unwrap());
        assert_eq!(b"f1", &buf[0..2]);
        assert_eq!(7, offset);

        close(rd).unwrap();
        close(wr).unwrap();
    }

    #[test]
    fn test_tee() {
        let (rd1, wr1) = pipe().unwrap();
        let (rd2, wr2) = pipe().unwrap();

        write(wr1, b"abc").unwrap();
        let res = tee(rd1, wr2, 2, SpliceFFlags::empty()).unwrap();

        assert_eq!(2, res);

        let mut buf = [0u8; 1024];

        // Check the tee'd bytes are at rd2.
        assert_eq!(2, read(rd2, &mut buf).unwrap());
        assert_eq!(b"ab", &buf[0..2]);

        // Check all the bytes are still at rd1.
        assert_eq!(3, read(rd1, &mut buf).unwrap());
        assert_eq!(b"abc", &buf[0..3]);

        close(rd1).unwrap();
        close(wr1).unwrap();
        close(rd2).unwrap();
        close(wr2).unwrap();
    }

    #[test]
    fn test_vmsplice() {
        let (rd, wr) = pipe().unwrap();

        let buf1 = b"abcdef";
        let buf2 = b"defghi";
        let mut iovecs = Vec::with_capacity(2);
        iovecs.push(IoVec::from_slice(&buf1[0..3]));
        iovecs.push(IoVec::from_slice(&buf2[0..3]));

        let res = vmsplice(wr, &iovecs[..], SpliceFFlags::empty()).unwrap();

        assert_eq!(6, res);

        // Check the bytes can be read at rd.
        let mut buf = [0u8; 32];
        assert_eq!(6, read(rd, &mut buf).unwrap());
        assert_eq!(b"abcdef", &buf[0..6]);

        close(rd).unwrap();
        close(wr).unwrap();
    }

    #[test]
    fn test_fallocate() {
        let tmp = NamedTempFile::new().unwrap();

        let fd = tmp.as_raw_fd();
        fallocate(fd, FallocateFlags::empty(), 0, 100).unwrap();

        // Check if we read exactly 100 bytes
        let mut buf = [0u8; 200];
        assert_eq!(100, read(fd, &mut buf).unwrap());
    }
}