//! Unix-specific filesystem extensions.

use std::io;
use std::path::Path;

use cfg_if::cfg_if;

use crate::task::blocking;

/// Creates a new symbolic link on the filesystem.
///
/// The `dst` path will be a symbolic link pointing to the `src` path.
///
/// This function is an async version of [`std::os::unix::fs::symlink`].
///
/// [`std::os::unix::fs::symlink`]: https://doc.rust-lang.org/std/os/unix/fs/fn.symlink.html
///
/// # Examples
///
/// ```no_run
/// # #![feature(async_await)]
/// use async_std::os::unix::fs::symlink;
///
/// # futures::executor::block_on(async {
/// symlink("a.txt", "b.txt").await?;
/// # std::io::Result::Ok(())
/// # }).unwrap();
/// ```
pub async fn symlink<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()> {
    let src = src.as_ref().to_owned();
    let dst = dst.as_ref().to_owned();
    blocking::spawn(async move { std::os::unix::fs::symlink(&src, &dst) }).await
}

cfg_if! {
    if #[cfg(feature = "docs.rs")] {
        /// Unix-specific extensions to `DirBuilder`.
        pub trait DirBuilderExt {
            /// Sets the mode to create new directories with. This option defaults to
            /// `0o777`.
            fn mode(&mut self, mode: u32) -> &mut Self;
        }

        /// Unix-specific extension methods for `DirEntry`.
        pub trait DirEntryExt {
            /// Returns the underlying `d_ino` field in the contained `dirent`
            /// structure.
            fn ino(&self) -> u64;
        }

        /// Unix-specific extensions to `OpenOptions`.
        pub trait OpenOptionsExt {
            /// Sets the mode bits that a new file will be created with.
            ///
            /// If a new file is created as part of a `File::open_opts` call then this
            /// specified `mode` will be used as the permission bits for the new file.
            /// If no `mode` is set, the default of `0o666` will be used.
            /// The operating system masks out bits with the systems `umask`, to produce
            /// the final permissions.
            fn mode(&mut self, mode: u32) -> &mut Self;

            /// Pass custom flags to the `flags` argument of `open`.
            ///
            /// The bits that define the access mode are masked out with `O_ACCMODE`, to
            /// ensure they do not interfere with the access mode set by Rusts options.
            ///
            /// Custom flags can only set flags, not remove flags set by Rusts options.
            /// This options overwrites any previously set custom flags.
            fn custom_flags(&mut self, flags: i32) -> &mut Self;
        }
    } else {
        #[doc(inline)]
        pub use std::os::unix::fs::{DirBuilderExt, OpenOptionsExt};
    }
}