rasio 0.1.1

use bitmask_enum::bitmask;
use futures::{future::poll_fn, AsyncRead, AsyncSeek, AsyncWrite, Stream};
use std::{
    io::{Result, SeekFrom},
    ops::Deref,
    path::{Path, PathBuf},
    sync::{Arc, OnceLock},
    task::{Context, Poll},
};

pub use std::fs::{FileType, Metadata, Permissions};

/// A bitmask for open file.
///
/// See [`open_file`](FileSystem::open_file) for more information.
#[bitmask(u8)]
pub enum FileOpenMode {
    /// Configures the option for append mode.
    ///
    /// When set to true, this option means the file will be writable after opening
    /// and the file cursor will be moved to the end of file before every write operaiton.
    Append,
    /// Configures the option for write mode.
    /// If the file already exists, write calls on it will overwrite the previous contents without truncating it.
    Writable,
    /// Configures the option for read mode.
    /// When set to true, this option means the file will be readable after opening.
    Readable,

    /// Configures the option for creating a new file if it doesn’t exist.
    /// When set to true, this option means a new file will be created if it doesn’t exist.
    /// The file must be opened in [`Writable`](FileOpenMode::Writable)
    /// or [`Append`](FileOpenMode::Append) mode for file creation to work.
    Create,

    /// Configures the option for creating a new file or failing if it already exists.
    /// When set to true, this option means a new file will be created, or the open
    /// operation will fail if the file already exists.
    /// The file must be opened in [`Writable`](FileOpenMode::Writable)
    /// or [`Append`](FileOpenMode::Append) mode for file creation to work.
    CreateNew,

    /// Configures the option for truncating the previous file.
    /// When set to true, the file will be truncated to the length of 0 bytes.
    /// The file must be opened in [`Writable`](FileOpenMode::Writable)
    /// or [`Append`](FileOpenMode::Append) mode for file creation to work.
    Truncate,
}

#[cfg(any(windows, docrs))]
pub mod windows {

    use std::io::ErrorKind;

    use super::*;

    pub trait FSDNamedPipeListener: Sync + Send {
        fn poll_ready(&self, cx: &mut Context<'_>) -> Poll<Result<()>>;

        fn poll_next(&self, cx: &mut Context<'_>) -> Poll<Result<NamedPipeStream>>;
    }

    pub struct NamedPipeListener(Box<dyn FSDNamedPipeListener>);

    impl Deref for NamedPipeListener {
        type Target = dyn FSDNamedPipeListener;
        fn deref(&self) -> &Self::Target {
            &*self.0
        }
    }

    impl<F: FSDNamedPipeListener + 'static> From<F> for NamedPipeListener {
        fn from(value: F) -> Self {
            Self(Box::new(value))
        }
    }

    impl NamedPipeListener {
        /// Returns internal `FSDNamedPipeListener` object.
        pub fn as_raw_ptr(&self) -> &dyn FSDNamedPipeListener {
            &*self.0
        }

        pub async fn accept(&self) -> Result<NamedPipeStream> {
            poll_fn(|cx| self.as_raw_ptr().poll_next(cx)).await
        }
    }

    impl Stream for NamedPipeListener {
        type Item = Result<NamedPipeStream>;

        fn poll_next(
            self: std::pin::Pin<&mut Self>,
            cx: &mut Context<'_>,
        ) -> Poll<Option<Self::Item>> {
            match self.as_raw_ptr().poll_next(cx) {
                Poll::Ready(Ok(stream)) => Poll::Ready(Some(Ok(stream))),
                Poll::Ready(Err(err)) => {
                    if err.kind() == ErrorKind::BrokenPipe {
                        Poll::Ready(None)
                    } else {
                        Poll::Ready(Some(Err(err)))
                    }
                }
                Poll::Pending => Poll::Pending,
            }
        }
    }

    pub trait FSDNamedPipeStream: Sync + Send {
        fn poll_ready(&self, cx: &mut Context<'_>) -> Poll<Result<()>>;

        /// Write a buffer into this writer, returning how many bytes were written
        fn poll_write(&self, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize>>;

        /// Pull some bytes from this source into the specified buffer, returning how many bytes were read.
        fn poll_read(&self, cx: &mut Context<'_>, buf: &mut [u8]) -> Poll<Result<usize>>;

        fn poll_close(&self, cx: &mut Context<'_>) -> Poll<Result<()>>;
    }

    pub struct NamedPipeStream(Arc<Box<dyn FSDNamedPipeStream>>);

    impl Deref for NamedPipeStream {
        type Target = dyn FSDNamedPipeStream;
        fn deref(&self) -> &Self::Target {
            &**self.0
        }
    }

    impl<F: FSDNamedPipeStream + 'static> From<F> for NamedPipeStream {
        fn from(value: F) -> Self {
            Self(Arc::new(Box::new(value)))
        }
    }

    impl NamedPipeStream {
        /// Returns internal `FSDNamedPipeStream` object.
        pub fn as_raw_ptr(&self) -> &dyn FSDNamedPipeStream {
            &**self.0
        }
    }

    impl AsyncRead for NamedPipeStream {
        fn poll_read(
            self: std::pin::Pin<&mut Self>,
            cx: &mut Context<'_>,
            buf: &mut [u8],
        ) -> Poll<Result<usize>> {
            self.as_raw_ptr().poll_read(cx, buf)
        }
    }

    impl AsyncWrite for NamedPipeStream {
        fn poll_write(
            self: std::pin::Pin<&mut Self>,
            cx: &mut Context<'_>,
            buf: &[u8],
        ) -> Poll<Result<usize>> {
            self.as_raw_ptr().poll_write(cx, buf)
        }

        fn poll_flush(self: std::pin::Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<()>> {
            Poll::Ready(Ok(()))
        }

        fn poll_close(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
            self.as_raw_ptr().poll_close(cx)
        }
    }
}

/// A driver is the main entry to access asynchronously filesystem functions
pub trait FileSystemDriver: Sync + Send {
    /// Open new file with provided `mode`.
    fn open_file(&self, path: &Path, mode: FileOpenMode) -> Result<File>;

    /// Returns the canonical form of a path.
    /// The returned path is in absolute form with all intermediate components
    /// normalized and symbolic links resolved.
    /// This function is an async version of [`std::fs::canonicalize`].
    fn canonicalize(&self, path: &Path) -> Result<PathBuf>;

    /// Copies the contents and permissions of a file to a new location.
    /// On success, the total number of bytes copied is returned and equals
    /// the length of the to file after this operation.
    /// The old contents of to will be overwritten. If from and to both point
    /// to the same file, then the file will likely get truncated as a result of this operation.
    fn poll_copy(&self, cx: &mut Context<'_>, from: &Path, to: &Path) -> Poll<Result<u64>>;

    /// Creates a new directory.
    /// Note that this function will only create the final directory in path.
    /// If you want to create all of its missing parent directories too, use
    /// the [`create_dir_all`](FileSystem::create_dir_all) function instead.
    ///
    /// This function is an async version of [`std::fs::create_dir`].
    fn poll_create_dir(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<()>>;

    /// Creates a new directory and all of its parents if they are missing.
    /// This function is an async version of [`std::fs::create_dir_all`].
    fn poll_create_dir_all(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<()>>;

    /// Creates a hard link on the filesystem.
    /// The dst path will be a link pointing to the src path. Note that operating
    /// systems often require these two paths to be located on the same filesystem.
    ///
    /// This function is an async version of [`std::fs::hard_link`].
    fn poll_hard_link(&self, cx: &mut Context<'_>, from: &Path, to: &Path) -> Poll<Result<()>>;

    /// Reads metadata for a path.
    /// This function will traverse symbolic links to read metadata for the target
    /// file or directory. If you want to read metadata without following symbolic
    /// links, use symlink_metadata instead.
    ///
    /// This function is an async version of [`std::fs::metadata`].
    fn poll_metadata(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<Metadata>>;

    /// Reads a symbolic link and returns the path it points to.
    ///
    /// This function is an async version of [`std::fs::read_link`].
    fn poll_read_link(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<PathBuf>>;

    /// Removes an empty directory,
    /// if the `path` is not an empty directory, use the function
    /// [`remove_dir_all`](FileSystem::remove_dir_all) instead.
    ///
    /// This function is an async version of std::fs::remove_dir.
    fn poll_remove_dir(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<()>>;

    /// Removes a directory and all of its contents.
    ///
    /// This function is an async version of [`std::fs::remove_dir_all`].
    fn poll_remove_dir_all(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<()>>;

    /// Removes a file.
    /// This function is an async version of [`std::fs::remove_file`].
    fn poll_remove_file(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<()>>;

    /// Renames a file or directory to a new location.
    /// If a file or directory already exists at the target location, it will be overwritten by this operation.
    /// This function is an async version of std::fs::rename.
    fn poll_rename(&self, cx: &mut Context<'_>, from: &Path, to: &Path) -> Poll<Result<()>>;

    /// Changes the permissions of a file or directory.
    /// This function is an async version of [`std::fs::set_permissions`].
    fn poll_set_permissions(
        &self,
        cx: &mut Context<'_>,
        path: &Path,
        perm: &Permissions,
    ) -> Poll<Result<()>>;

    /// Reads metadata for a path without following symbolic links.
    /// If you want to follow symbolic links before reading metadata of the target file or directory,
    /// use [`metadata`](FileSystem::metadata) instead.
    ///
    /// This function is an async version of [`std::fs::symlink_metadata`].
    fn poll_symlink_metadata(&self, cx: &mut Context<'_>, path: &Path) -> Poll<Result<Metadata>>;

    /// Returns a iterator handle of entries in a directory.
    ///
    /// See [`dir_entry_next`](FileSystem::dir_entry_next) for more information about iteration.
    fn read_dir(&self, path: &Path) -> Result<ReadDir>;

    #[cfg(any(windows))]
    /// Opens the named pipe identified by `addr`.
    fn named_pipe_client_open(&self, addr: &std::ffi::OsStr) -> Result<windows::NamedPipeStream>;

    #[cfg(any(windows))]
    /// Creates the named pipe identified by `addr` for use as a server.
    ///
    /// This uses the [`CreateNamedPipe`] function.
    fn named_pipe_server_create(
        &self,
        addr: &std::ffi::OsStr,
    ) -> Result<windows::NamedPipeListener>;
}

pub trait FSDDirEntry: Sync + Send {
    /// Returns the bare name of this entry without the leading path.
    fn name(&self) -> String;

    /// Returns the full path to this entry.
    /// The full path is created by joining the original path passed to [`read_dir`](FileSystemDriver::read_dir) with the name of this entry.
    fn path(&self) -> PathBuf;

    /// Reads the metadata for this entry.
    ///
    /// This function will traverse symbolic links to read the metadata.
    fn meta(&self) -> Result<Metadata>;

    /// eads the file type for this entry.
    /// This function will not traverse symbolic links if this entry points at one.
    /// If you want to read metadata with following symbolic links, use [`meta`](FSDDirEntry::meta) instead.
    fn file_type(&self) -> Result<FileType>;
}

pub struct DirEntry(Box<dyn FSDDirEntry>);

impl Deref for DirEntry {
    type Target = dyn FSDDirEntry;
    fn deref(&self) -> &Self::Target {
        &*self.0
    }
}

impl<F: FSDDirEntry + 'static> From<F> for DirEntry {
    fn from(value: F) -> Self {
        Self(Box::new(value))
    }
}

impl DirEntry {
    /// Returns internal `FSDDirEntry` object.
    pub fn as_raw_ptr(&self) -> &dyn FSDDirEntry {
        &*self.0
    }
}

pub trait FSDReadDir: Sync + Send {
    /// Get asynchronously opened event.
    fn poll_ready(&self, cx: &mut Context<'_>) -> Poll<Result<()>>;

    fn poll_next(&self, cx: &mut Context<'_>) -> Poll<Option<Result<DirEntry>>>;
}

pub struct ReadDir(Box<dyn FSDReadDir>);

impl Deref for ReadDir {
    type Target = dyn FSDReadDir;
    fn deref(&self) -> &Self::Target {
        &*self.0
    }
}

impl<F: FSDReadDir + 'static> From<F> for ReadDir {
    fn from(value: F) -> Self {
        Self(Box::new(value))
    }
}

impl ReadDir {
    /// Returns internal `FSDReadDir` object.
    pub fn as_raw_ptr(&self) -> &dyn FSDReadDir {
        &*self.0
    }

    pub async fn new<P: AsRef<Path>>(path: P) -> Result<Self> {
        Self::new_with(path, get_fs_driver()).await
    }

    pub async fn new_with<P: AsRef<Path>>(path: P, driver: &dyn FileSystemDriver) -> Result<Self> {
        let readdir = driver.read_dir(path.as_ref())?;

        poll_fn(|cx| readdir.as_raw_ptr().poll_ready(cx))
            .await
            .map(|_| readdir)
    }
}

impl Stream for ReadDir {
    type Item = Result<DirEntry>;
    fn poll_next(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        self.as_raw_ptr().poll_next(cx)
    }
}

/// Driver-specific `File` object.
pub trait FSDFile: Sync + Send {
    /// Poll if the file object is actually opened.
    fn poll_ready(&self, cx: &mut Context<'_>) -> Poll<Result<()>>;

    /// Write a buffer into this writer, returning how many bytes were written
    fn poll_write(&self, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize>>;

    /// Pull some bytes from this source into the specified buffer, returning how many bytes were read.
    fn poll_read(&self, cx: &mut Context<'_>, buf: &mut [u8]) -> Poll<Result<usize>>;

    /// Attempts to sync all OS-internal metadata to disk.
    ///
    /// This function will attempt to ensure that all in-memory data reaches the filesystem before returning.
    ///
    /// This can be used to handle errors that would otherwise only be caught when the File is closed.
    /// Dropping a file will ignore errors in synchronizing this in-memory data.
    fn poll_flush(&self, cx: &mut Context<'_>) -> Poll<Result<()>>;

    /// Seek to an offset, in bytes, in a stream.
    ///
    /// A seek beyond the end of a stream is allowed, but behavior is defined by the implementation.
    ///
    /// If the seek operation completed successfully, this method returns the new position from the
    /// start of the stream. That position can be used later with [`SeekFrom::Start`].
    ///
    /// # Errors
    /// Seeking can fail, for example because it might involve flushing a buffer.
    ///
    /// Seeking to a negative offset is considered an error.
    fn poll_seek(&self, cx: &mut Context<'_>, pos: SeekFrom) -> Poll<Result<u64>>;

    ///  Reads the file's metadata.
    fn poll_meta(&self, cx: &mut Context<'_>) -> Poll<Result<Metadata>>;

    /// Changes the permissions on the file.
    fn poll_set_permissions(&self, cx: &mut Context<'_>, perm: &Permissions) -> Poll<Result<()>>;

    /// Truncates or extends the file.
    ///
    /// If `size` is less than the current file size, then the file will be truncated. If it is
    /// greater than the current file size, then the file will be extended to `size` and have all
    /// intermediate data filled with zeros.
    ///
    /// The file's cursor stays at the same position, even if the cursor ends up being past the end
    /// of the file after this operation.
    ///
    fn poll_set_len(&self, cx: &mut Context<'_>, size: u64) -> Poll<Result<()>>;
}

/// An open file on the filesystem.
///
/// Depending on what options the file was opened with, this type can be used for reading and/or writing.
/// Files are automatically closed when they get dropped and any errors detected on closing are ignored.
/// Use the sync_all method before dropping a file if such errors need to be handled.
///
/// This type is an async version of std::fs::File.
pub struct File(Arc<Box<dyn FSDFile>>);

impl Deref for File {
    type Target = dyn FSDFile;
    fn deref(&self) -> &Self::Target {
        &**self.0
    }
}

impl<F: FSDFile + 'static> From<F> for File {
    fn from(value: F) -> Self {
        Self(Arc::new(Box::new(value)))
    }
}

impl File {
    /// Returns internal `FSDFile` object.
    pub fn as_raw_ptr(&self) -> &dyn FSDFile {
        &**self.0
    }

    /// Open a file with provided `FileOpenMode`.
    pub async fn open<P: AsRef<Path>>(path: P, mode: FileOpenMode) -> Result<Self> {
        Self::open_with(path, mode, get_fs_driver()).await
    }

    /// Use custom `FileSystemDriver` to open file.
    pub async fn open_with<P: AsRef<Path>>(
        path: P,
        mode: FileOpenMode,
        driver: &dyn FileSystemDriver,
    ) -> Result<Self> {
        let file = driver.open_file(path.as_ref(), mode)?;

        // Wait for file opened event.
        poll_fn(|cx| file.as_raw_ptr().poll_ready(cx)).await?;

        Ok(file)
    }

    pub async fn meta(&self) -> Result<Metadata> {
        poll_fn(|cx| self.as_raw_ptr().poll_meta(cx)).await
    }

    pub async fn set_permissions(&self, perm: &Permissions) -> Result<()> {
        poll_fn(|cx| self.as_raw_ptr().poll_set_permissions(cx, perm)).await
    }

    pub async fn set_len(&self, len: u64) -> Result<()> {
        poll_fn(|cx| self.as_raw_ptr().poll_set_len(cx, len)).await
    }
}

impl AsyncRead for File {
    fn poll_read(
        self: std::pin::Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &mut [u8],
    ) -> Poll<Result<usize>> {
        self.as_raw_ptr().poll_read(cx, buf)
    }
}

impl AsyncWrite for File {
    fn poll_write(
        self: std::pin::Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<Result<usize>> {
        self.as_raw_ptr().poll_write(cx, buf)
    }

    fn poll_flush(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
        self.as_raw_ptr().poll_flush(cx)
    }

    fn poll_close(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
        self.poll_flush(cx)
    }
}

impl AsyncSeek for File {
    fn poll_seek(
        self: std::pin::Pin<&mut Self>,
        cx: &mut Context<'_>,
        pos: SeekFrom,
    ) -> Poll<Result<u64>> {
        self.as_raw_ptr().poll_seek(cx, pos)
    }
}

/// Returns the canonical form of a path.
/// The returned path is in absolute form with all intermediate components
/// normalized and symbolic links resolved.
/// This function is an async version of [`std::fs::canonicalize`].
pub async fn canonicalize<P: AsRef<Path>>(path: P) -> Result<PathBuf> {
    get_fs_driver().canonicalize(path.as_ref())
}

/// Copies the contents and permissions of a file to a new location.
/// On success, the total number of bytes copied is returned and equals
/// the length of the to file after this operation.
/// The old contents of to will be overwritten. If from and to both point
/// to the same file, then the file will likely get truncated as a result of this operation.
pub async fn copy<F: AsRef<Path>, T: AsRef<Path>>(from: F, to: T) -> Result<u64> {
    poll_fn(|cx| get_fs_driver().poll_copy(cx, from.as_ref(), to.as_ref())).await
}

/// Creates a new directory.
/// Note that this function will only create the final directory in path.
/// If you want to create all of its missing parent directories too, use
/// the [`create_dir_all`](FileSystem::create_dir_all) function instead.
///
/// This function is an async version of [`std::fs::create_dir`].
pub async fn create_dir<P: AsRef<Path>>(path: P) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_create_dir(cx, path.as_ref())).await
}

/// Creates a new directory and all of its parents if they are missing.
/// This function is an async version of [`std::fs::create_dir_all`].
pub async fn create_dir_all<P: AsRef<Path>>(path: P) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_create_dir_all(cx, path.as_ref())).await
}

/// Creates a hard link on the filesystem.
/// The dst path will be a link pointing to the src path. Note that operating
/// systems often require these two paths to be located on the same filesystem.
///
/// This function is an async version of [`std::fs::hard_link`].
pub async fn hard_link<F: AsRef<Path>, T: AsRef<Path>>(from: F, to: T) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_hard_link(cx, from.as_ref(), to.as_ref())).await
}

/// Reads metadata for a path.
/// This function will traverse symbolic links to read metadata for the target
/// file or directory. If you want to read metadata without following symbolic
/// links, use symlink_metadata instead.
///
/// This function is an async version of [`std::fs::metadata`].
pub async fn metadata<P: AsRef<Path>>(path: P) -> Result<Metadata> {
    poll_fn(|cx| get_fs_driver().poll_metadata(cx, path.as_ref())).await
}

/// Reads a symbolic link and returns the path it points to.
///
/// This function is an async version of [`std::fs::read_link`].
pub async fn read_link<P: AsRef<Path>>(path: P) -> Result<PathBuf> {
    poll_fn(|cx| get_fs_driver().poll_read_link(cx, path.as_ref())).await
}

/// Removes an empty directory,
/// if the `path` is not an empty directory, use the function
/// [`remove_dir_all`](FileSystem::remove_dir_all) instead.
///
/// This function is an async version of std::fs::remove_dir.
pub async fn remove_dir<P: AsRef<Path>>(path: P) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_remove_dir(cx, path.as_ref())).await
}

/// Removes a directory and all of its contents.
///
/// This function is an async version of [`std::fs::remove_dir_all`].
pub async fn remove_dir_all<P: AsRef<Path>>(path: P) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_remove_dir_all(cx, path.as_ref())).await
}

/// Removes a file.
/// This function is an async version of [`std::fs::remove_file`].
pub async fn remove_file<P: AsRef<Path>>(path: P) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_remove_file(cx, path.as_ref())).await
}

/// Renames a file or directory to a new location.
/// If a file or directory already exists at the target location, it will be overwritten by this operation.
/// This function is an async version of std::fs::rename.
pub async fn rename<F: AsRef<Path>, T: AsRef<Path>>(from: F, to: T) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_rename(cx, from.as_ref(), to.as_ref())).await
}

/// Changes the permissions of a file or directory.
/// This function is an async version of [`std::fs::set_permissions`].
pub async fn set_permissions<P: AsRef<Path>>(path: P, perm: &Permissions) -> Result<()> {
    poll_fn(|cx| get_fs_driver().poll_set_permissions(cx, path.as_ref(), perm)).await
}

/// Reads metadata for a path without following symbolic links.
/// If you want to follow symbolic links before reading metadata of the target file or directory,
/// use [`metadata`](FileSystem::metadata) instead.
///
/// This function is an async version of [`std::fs::symlink_metadata`].
pub async fn symlink_metadata<P: AsRef<Path>>(path: P) -> Result<Metadata> {
    poll_fn(|cx| get_fs_driver().poll_symlink_metadata(cx, path.as_ref())).await
}

/// Returns `true` if the path exists on disk and is pointing at a directory.
///
/// This function will traverse symbolic links to query information about the
/// destination file. In case of broken symbolic links this will return `false`.
///
/// If you cannot access the directory containing the file, e.g., because of a
/// permission error, this will return `false`.
///
/// # See Also
///
/// This is a convenience function that coerces errors to false. If you want to
/// check errors, call [fs::metadata] and handle its Result. Then call
/// [fs::Metadata::is_dir] if it was Ok.
///
/// [fs::metadata]: ../fs/fn.metadata.html
/// [fs::Metadata::is_dir]: ../fs/struct.Metadata.html#method.is_dir
pub async fn is_dir<P: AsRef<Path>>(path: P) -> bool {
    metadata(path).await.map(|m| m.is_dir()).unwrap_or(false)
}

pub struct FileSystem<'a> {
    driver: &'a dyn FileSystemDriver,
}

impl<'a> From<&'a dyn FileSystemDriver> for FileSystem<'a> {
    fn from(value: &'a dyn FileSystemDriver) -> Self {
        Self { driver: value }
    }
}

impl<'a> FileSystem<'a> {
    /// Returns `true` if the path exists on disk and is pointing at a directory.
    ///
    /// This function will traverse symbolic links to query information about the
    /// destination file. In case of broken symbolic links this will return `false`.
    ///
    /// If you cannot access the directory containing the file, e.g., because of a
    /// permission error, this will return `false`.
    ///
    ///
    /// # See Also
    ///
    /// This is a convenience function that coerces errors to false. If you want to
    /// check errors, call [fs::metadata] and handle its Result. Then call
    /// [fs::Metadata::is_dir] if it was Ok.
    ///
    /// [fs::metadata]: ../fs/fn.metadata.html
    /// [fs::Metadata::is_dir]: ../fs/struct.Metadata.html#method.is_dir
    pub async fn is_dir<P: AsRef<Path>>(&self, path: P) -> bool {
        self.metadata(path)
            .await
            .map(|m| m.is_dir())
            .unwrap_or(false)
    }

    /// Returns `true` if the path exists on disk and is pointing at a regular file.
    ///
    /// This function will traverse symbolic links to query information about the
    /// destination file. In case of broken symbolic links this will return `false`.
    ///
    /// If you cannot access the directory containing the file, e.g., because of a
    /// permission error, this will return `false`.
    ///
    /// # See Also
    ///
    /// This is a convenience function that coerces errors to false. If you want to
    /// check errors, call [fs::metadata] and handle its Result. Then call
    /// [fs::Metadata::is_file] if it was Ok.
    ///
    /// [fs::metadata]: ../fs/fn.metadata.html
    /// [fs::Metadata::is_file]: ../fs/struct.Metadata.html#method.is_file

    pub async fn is_file<P: AsRef<Path>>(&self, path: P) -> bool {
        self.metadata(path)
            .await
            .map(|m| m.is_file())
            .unwrap_or(false)
    }

    pub async fn open_file<P: AsRef<Path>>(&self, path: P, mode: FileOpenMode) -> Result<File> {
        File::open_with(path, mode, self.driver).await
    }

    /// Returns the canonical form of a path.
    /// The returned path is in absolute form with all intermediate components
    /// normalized and symbolic links resolved.
    /// This function is an async version of [`std::fs::canonicalize`].
    pub async fn canonicalize<P: AsRef<Path>>(&self, path: P) -> Result<PathBuf> {
        self.driver.canonicalize(path.as_ref())
    }

    /// Copies the contents and permissions of a file to a new location.
    /// On success, the total number of bytes copied is returned and equals
    /// the length of the to file after this operation.
    /// The old contents of to will be overwritten. If from and to both point
    /// to the same file, then the file will likely get truncated as a result of this operation.
    pub async fn copy<F: AsRef<Path>, T: AsRef<Path>>(&self, from: F, to: T) -> Result<u64> {
        poll_fn(|cx| self.driver.poll_copy(cx, from.as_ref(), to.as_ref())).await
    }

    /// Creates a new directory.
    /// Note that this function will only create the final directory in path.
    /// If you want to create all of its missing parent directories too, use
    /// the [`create_dir_all`](FileSystem::create_dir_all) function instead.
    ///
    /// This function is an async version of [`std::fs::create_dir`].
    pub async fn create_dir<P: AsRef<Path>>(&self, path: P) -> Result<()> {
        poll_fn(|cx| self.driver.poll_create_dir(cx, path.as_ref())).await
    }

    /// Creates a new directory and all of its parents if they are missing.
    /// This function is an async version of [`std::fs::create_dir_all`].
    pub async fn create_dir_all<P: AsRef<Path>>(&self, path: P) -> Result<()> {
        poll_fn(|cx| self.driver.poll_create_dir_all(cx, path.as_ref())).await
    }

    /// Creates a hard link on the filesystem.
    /// The dst path will be a link pointing to the src path. Note that operating
    /// systems often require these two paths to be located on the same filesystem.
    ///
    /// This function is an async version of [`std::fs::hard_link`].
    pub async fn hard_link<F: AsRef<Path>, T: AsRef<Path>>(&self, from: F, to: T) -> Result<()> {
        poll_fn(|cx| self.driver.poll_hard_link(cx, from.as_ref(), to.as_ref())).await
    }

    /// Reads metadata for a path.
    /// This function will traverse symbolic links to read metadata for the target
    /// file or directory. If you want to read metadata without following symbolic
    /// links, use symlink_metadata instead.
    ///
    /// This function is an async version of [`std::fs::metadata`].
    pub async fn metadata<P: AsRef<Path>>(&self, path: P) -> Result<Metadata> {
        poll_fn(|cx| self.driver.poll_metadata(cx, path.as_ref())).await
    }

    /// Reads a symbolic link and returns the path it points to.
    ///
    /// This function is an async version of [`std::fs::read_link`].
    pub async fn read_link<P: AsRef<Path>>(&self, path: P) -> Result<PathBuf> {
        poll_fn(|cx| self.driver.poll_read_link(cx, path.as_ref())).await
    }

    /// Removes an empty directory,
    /// if the `path` is not an empty directory, use the function
    /// [`remove_dir_all`](FileSystem::remove_dir_all) instead.
    ///
    /// This function is an async version of std::fs::remove_dir.
    pub async fn remove_dir<P: AsRef<Path>>(&self, path: P) -> Result<()> {
        poll_fn(|cx| self.driver.poll_remove_dir(cx, path.as_ref())).await
    }

    /// Removes a directory and all of its contents.
    ///
    /// This function is an async version of [`std::fs::remove_dir_all`].
    pub async fn remove_dir_all<P: AsRef<Path>>(&self, path: P) -> Result<()> {
        poll_fn(|cx| self.driver.poll_remove_dir_all(cx, path.as_ref())).await
    }

    /// Removes a file.
    /// This function is an async version of [`std::fs::remove_file`].
    pub async fn remove_file<P: AsRef<Path>>(&self, path: P) -> Result<()> {
        poll_fn(|cx| self.driver.poll_remove_file(cx, path.as_ref())).await
    }

    /// Renames a file or directory to a new location.
    /// If a file or directory already exists at the target location, it will be overwritten by this operation.
    /// This function is an async version of std::fs::rename.
    pub async fn rename<F: AsRef<Path>, T: AsRef<Path>>(&self, from: F, to: T) -> Result<()> {
        poll_fn(|cx| self.driver.poll_rename(cx, from.as_ref(), to.as_ref())).await
    }

    /// Changes the permissions of a file or directory.
    /// This function is an async version of [`std::fs::set_permissions`].
    pub async fn set_permissions<P: AsRef<Path>>(&self, path: P, perm: &Permissions) -> Result<()> {
        poll_fn(|cx| self.driver.poll_set_permissions(cx, path.as_ref(), perm)).await
    }

    /// Reads metadata for a path without following symbolic links.
    /// If you want to follow symbolic links before reading metadata of the target file or directory,
    /// use [`metadata`](FileSystem::metadata) instead.
    ///
    /// This function is an async version of [`std::fs::symlink_metadata`].
    pub async fn symlink_metadata<P: AsRef<Path>>(&self, path: P) -> Result<Metadata> {
        poll_fn(|cx| self.driver.poll_symlink_metadata(cx, path.as_ref())).await
    }
}

static FIFLE_SYSTEM_DRIVER: OnceLock<Box<dyn FileSystemDriver>> = OnceLock::new();

/// Get global register `FileSystemDriver` instance.
pub fn get_fs_driver() -> &'static dyn FileSystemDriver {
    FIFLE_SYSTEM_DRIVER
        .get()
        .expect("Call register_network_driver first.")
        .as_ref()
}

/// Register provided [`FileSystemDriver`] as global network implementation.
///
/// # Panic
///
/// Multiple calls to this function are not permitted!!!
pub fn register_fs_driver<E: FileSystemDriver + 'static>(driver: E) {
    if FIFLE_SYSTEM_DRIVER.set(Box::new(driver)).is_err() {
        panic!("Multiple calls to register_network_driver are not permitted!!!");
    }
}