#[cfg(with_options)]
use crate::fs::OpenOptions;
use crate::fs::{Metadata, Permissions};
use cap_primitives::fs::is_file_read_write;
#[cfg(unix)]
use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
#[cfg(target_os = "wasi")]
use std::os::wasi::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
#[cfg(windows)]
use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
#[cfg(target_os = "wasi")]
use std::path::Path;
use std::{
    fmt, fs,
    io::{self, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write},
    process,
};

/// A reference to an open file on a filesystem.
///
/// This corresponds to [`std::fs::File`].
///
/// Note that this `File` has no `open` or `create` methods. To open or create
/// a file, you must first obtain a [`Dir`] containing the path, and then call
/// [`Dir::open`] or [`Dir::create`].
///
/// [`Dir`]: crate::fs::Dir
/// [`Dir::open`]: crate::fs::Dir::open
/// [`Dir::create`]: crate::fs::Dir::create
pub struct File {
    pub(crate) std: fs::File,
}

impl File {
    /// Constructs a new instance of `Self` from the given `std::fs::File`.
    ///
    /// # Safety
    ///
    /// `std::fs::File` is not sandboxed and may access any path that the host
    #[inline]
    pub unsafe fn from_std(std: fs::File) -> Self {
        Self { std }
    }

    /// Consumes `self` and returns a `std::fs::File`.
    #[inline]
    pub fn into_std(self) -> fs::File {
        self.std
    }

    /// Returns a new `OpenOptions` object.
    ///
    /// This corresponds to [`std::fs::File::with_options`].
    #[inline]
    #[cfg(with_options)]
    pub fn with_options() -> OpenOptions {
        OpenOptions::new()
    }

    /// Attempts to sync all OS-internal metadata to disk.
    ///
    /// This corresponds to [`std::fs::File::sync_all`].
    #[inline]
    pub fn sync_all(&self) -> io::Result<()> {
        self.std.sync_all()
    }

    /// This function is similar to `sync_all`, except that it may not synchronize
    /// file metadata to a filesystem.
    ///
    /// This corresponds to [`std::fs::File::sync_data`].
    #[inline]
    pub fn sync_data(&self) -> io::Result<()> {
        self.std.sync_data()
    }

    /// Truncates or extends the underlying file, updating the size of this file
    /// to become size.
    ///
    /// This corresponds to [`std::fs::File::set_len`].
    #[inline]
    pub fn set_len(&self, size: u64) -> io::Result<()> {
        self.std.set_len(size)
    }

    /// Queries metadata about the underlying file.
    ///
    /// This corresponds to [`std::fs::File::metadata`].
    #[inline]
    pub fn metadata(&self) -> io::Result<Metadata> {
        metadata_from(&self.std)
    }

    /// Creates a new `File` instance that shares the same underlying file handle as the existing
    /// `File` instance.
    ///
    /// This corresponds to [`std::fs::File::try_clone`].
    #[inline]
    pub fn try_clone(&self) -> io::Result<Self> {
        let file = self.std.try_clone()?;
        Ok(unsafe { Self::from_std(file) })
    }

    /// Changes the permissions on the underlying file.
    ///
    /// This corresponds to [`std::fs::File::set_permissions`].
    #[inline]
    pub fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
        self.std
            .set_permissions(permissions_into_std(&self.std, perm)?)
    }
}

#[cfg(not(target_os = "wasi"))]
#[inline]
fn metadata_from(file: &fs::File) -> io::Result<Metadata> {
    Metadata::from_file(file)
}

#[cfg(target_os = "wasi")]
#[inline]
fn metadata_from(file: &fs::File) -> io::Result<Metadata> {
    file.metadata()
}

#[cfg(not(target_os = "wasi"))]
#[inline]
fn permissions_into_std(file: &fs::File, permissions: Permissions) -> io::Result<fs::Permissions> {
    permissions.into_std(file)
}

#[cfg(target_os = "wasi")]
#[inline]
fn permissions_into_std(_file: &fs::File, permissions: Permissions) -> io::Result<fs::Permissions> {
    permissions
}

#[cfg(not(windows))]
impl FromRawFd for File {
    #[inline]
    unsafe fn from_raw_fd(fd: RawFd) -> Self {
        Self::from_std(fs::File::from_raw_fd(fd))
    }
}

#[cfg(windows)]
impl FromRawHandle for File {
    #[inline]
    unsafe fn from_raw_handle(handle: RawHandle) -> Self {
        Self::from_std(fs::File::from_raw_handle(handle))
    }
}

#[cfg(not(windows))]
impl AsRawFd for File {
    #[inline]
    fn as_raw_fd(&self) -> RawFd {
        self.std.as_raw_fd()
    }
}

#[cfg(windows)]
impl AsRawHandle for File {
    #[inline]
    fn as_raw_handle(&self) -> RawHandle {
        self.std.as_raw_handle()
    }
}

#[cfg(not(windows))]
impl IntoRawFd for File {
    #[inline]
    fn into_raw_fd(self) -> RawFd {
        self.std.into_raw_fd()
    }
}

#[cfg(windows)]
impl IntoRawHandle for File {
    #[inline]
    fn into_raw_handle(self) -> RawHandle {
        self.std.into_raw_handle()
    }
}

impl Read for File {
    #[inline]
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        self.std.read(buf)
    }

    #[inline]
    fn read_vectored(&mut self, bufs: &mut [IoSliceMut]) -> io::Result<usize> {
        self.std.read_vectored(bufs)
    }

    #[inline]
    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
        self.std.read_exact(buf)
    }

    #[inline]
    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
        self.std.read_to_end(buf)
    }

    #[inline]
    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
        self.std.read_to_string(buf)
    }

    #[cfg(can_vector)]
    #[inline]
    fn is_read_vectored(&self) -> bool {
        self.std.is_read_vectored()
    }
}

impl Read for &File {
    #[inline]
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        (&mut &self.std).read(buf)
    }

    #[inline]
    fn read_vectored(&mut self, bufs: &mut [IoSliceMut]) -> io::Result<usize> {
        (&mut &self.std).read_vectored(bufs)
    }

    #[inline]
    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
        (&mut &self.std).read_exact(buf)
    }

    #[inline]
    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
        (&mut &self.std).read_to_end(buf)
    }

    #[inline]
    fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
        (&mut &self.std).read_to_string(buf)
    }

    #[cfg(can_vector)]
    #[inline]
    fn is_read_vectored(&self) -> bool {
        (&mut &self.std).is_read_vectored()
    }
}

impl Write for File {
    #[inline]
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.std.write(buf)
    }

    #[inline]
    fn flush(&mut self) -> io::Result<()> {
        self.std.flush()
    }

    #[inline]
    fn write_vectored(&mut self, bufs: &[IoSlice]) -> io::Result<usize> {
        self.std.write_vectored(bufs)
    }

    #[inline]
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        self.std.write_all(buf)
    }

    #[cfg(can_vector)]
    #[inline]
    fn is_write_vectored(&self) -> bool {
        self.std.is_write_vectored()
    }

    #[cfg(write_all_vectored)]
    #[inline]
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice]) -> io::Result<()> {
        self.std.write_all_vectored(bufs)
    }
}

impl Write for &File {
    #[inline]
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        (&mut &self.std).write(buf)
    }

    #[inline]
    fn flush(&mut self) -> io::Result<()> {
        (&mut &self.std).flush()
    }

    #[inline]
    fn write_vectored(&mut self, bufs: &[IoSlice]) -> io::Result<usize> {
        (&mut &self.std).write_vectored(bufs)
    }

    #[inline]
    fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
        (&mut &self.std).write_all(buf)
    }

    #[cfg(can_vector)]
    #[inline]
    fn is_write_vectored(&self) -> bool {
        (&mut &self.std).is_write_vectored()
    }

    #[cfg(write_all_vectored)]
    #[inline]
    fn write_all_vectored(&mut self, bufs: &mut [IoSlice]) -> io::Result<()> {
        (&mut &self.std).write_all_vectored(bufs)
    }
}

impl Seek for File {
    #[inline]
    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
        self.std.seek(pos)
    }

    #[cfg(seek_convenience)]
    #[inline]
    fn stream_len(&mut self) -> io::Result<u64> {
        self.std.stream_len()
    }

    #[cfg(seek_convenience)]
    #[inline]
    fn stream_position(&mut self) -> io::Result<u64> {
        self.std.stream_position()
    }
}

impl Seek for &File {
    #[inline]
    fn seek(&mut self, pos: SeekFrom) -> io::Result<u64> {
        (&mut &self.std).seek(pos)
    }

    #[cfg(seek_convenience)]
    #[inline]
    fn stream_len(&mut self) -> io::Result<u64> {
        (&mut &self.std).stream_len()
    }

    #[cfg(seek_convenience)]
    #[inline]
    fn stream_position(&mut self) -> io::Result<u64> {
        (&mut &self.std).stream_position()
    }
}

impl From<File> for process::Stdio {
    #[inline]
    fn from(file: File) -> Self {
        From::<fs::File>::from(file.std)
    }
}

#[cfg(unix)]
impl std::os::unix::fs::FileExt for File {
    #[inline]
    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
        self.std.read_at(buf, offset)
    }

    #[inline]
    fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
        self.std.write_at(buf, offset)
    }

    #[inline]
    fn read_exact_at(&self, buf: &mut [u8], offset: u64) -> io::Result<()> {
        self.std.read_exact_at(buf, offset)
    }

    #[inline]
    fn write_all_at(&self, buf: &[u8], offset: u64) -> io::Result<()> {
        self.std.write_all_at(buf, offset)
    }
}

#[cfg(target_os = "wasi")]
impl std::os::wasi::fs::FileExt for File {
    #[inline]
    fn read_at(&self, bufs: &mut [IoSliceMut], offset: u64) -> io::Result<usize> {
        self.std.read_at(bufs, offset)
    }

    #[inline]
    fn write_at(&self, bufs: &[IoSlice], offset: u64) -> io::Result<usize> {
        self.std.write_at(bufs, offset)
    }

    #[inline]
    fn tell(&self) -> std::result::Result<u64, std::io::Error> {
        self.std.tell()
    }

    #[inline]
    fn fdstat_set_flags(&self, flags: u16) -> std::result::Result<(), std::io::Error> {
        self.std.fdstat_set_flags(flags)
    }

    #[inline]
    fn fdstat_set_rights(
        &self,
        rights: u64,
        inheriting: u64,
    ) -> std::result::Result<(), std::io::Error> {
        self.std.fdstat_set_rights(rights, inheriting)
    }

    #[inline]
    fn advise(&self, offset: u64, len: u64, advice: u8) -> std::result::Result<(), std::io::Error> {
        self.std.advise(offset, len, advice)
    }

    #[inline]
    fn allocate(&self, offset: u64, len: u64) -> std::result::Result<(), std::io::Error> {
        self.std.allocate(offset, len)
    }

    #[inline]
    fn create_directory<P: AsRef<Path>>(&self, dir: P) -> std::result::Result<(), std::io::Error> {
        self.std.create_directory(dir)
    }

    #[inline]
    fn read_link<P: AsRef<Path>>(
        &self,
        path: P,
    ) -> std::result::Result<std::path::PathBuf, std::io::Error> {
        self.std.read_link(path)
    }

    #[inline]
    fn metadata_at<P: AsRef<Path>>(
        &self,
        lookup_flags: u32,
        path: P,
    ) -> std::result::Result<std::fs::Metadata, std::io::Error> {
        self.std.metadata_at(lookup_flags, path)
    }

    #[inline]
    fn remove_file<P: AsRef<Path>>(&self, path: P) -> std::result::Result<(), std::io::Error> {
        self.std.remove_file(path)
    }

    #[inline]
    fn remove_directory<P: AsRef<Path>>(&self, path: P) -> std::result::Result<(), std::io::Error> {
        self.std.remove_directory(path)
    }
}

#[cfg(windows)]
impl std::os::windows::fs::FileExt for File {
    #[inline]
    fn seek_read(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
        self.std.seek_read(buf, offset)
    }

    #[inline]
    fn seek_write(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
        self.std.seek_write(buf, offset)
    }
}

impl fmt::Debug for File {
    // Like libstd's version, but doesn't print the path.
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let mut b = f.debug_struct("File");
        #[cfg(not(windows))]
        b.field("fd", &self.std.as_raw_fd());
        #[cfg(windows)]
        b.field("handle", &self.std.as_raw_handle());
        if let Ok((read, write)) = is_file_read_write(&self.std) {
            b.field("read", &read).field("write", &write);
        }
        b.finish()
    }
}
