package fs

import (
	"fmt"
	"os"
	"path/filepath"
	"time"
)

// Mkdir creates a new directory with the specified name and permission bits.
// If there is an error, it will be of type *PathError.
func Mkdir(name string, perm os.FileMode) error {
	return os.Mkdir(fixpath(name), perm)
}

// MkdirAll creates a directory named path, along with any necessary parents,
// and returns nil, or else returns an error. The permission bits perm are used
// for all directories that MkdirAll creates. If path is already a directory,
// MkdirAll does nothing and returns nil.
func MkdirAll(path string, perm os.FileMode) error {
	return os.MkdirAll(fixpath(path), perm)
}

// Readlink returns the destination of the named symbolic link.
// If there is an error, it will be of type *PathError.
func Readlink(name string) (string, error) {
	return os.Readlink(fixpath(name))
}

// Remove removes the named file or directory.
// If there is an error, it will be of type *PathError.
func Remove(name string) error {
	return os.Remove(fixpath(name))
}

// RemoveAll removes path and any children it contains.
// It removes everything it can but returns the first error
// it encounters.  If the path does not exist, RemoveAll
// returns nil (no error).
func RemoveAll(path string) error {
	return os.RemoveAll(fixpath(path))
}

// Rename renames (moves) oldpath to newpath.
// If newpath already exists, Rename replaces it.
// OS-specific restrictions may apply when oldpath and newpath are in different directories.
// If there is an error, it will be of type *LinkError.
func Rename(oldpath, newpath string) error {
	return os.Rename(fixpath(oldpath), fixpath(newpath))
}

// Symlink creates newname as a symbolic link to oldname.
// If there is an error, it will be of type *LinkError.
func Symlink(oldname, newname string) error {
	return os.Symlink(oldname, fixpath(newname))
}

// Link creates newname as a hard link to oldname.
// If there is an error, it will be of type *LinkError.
func Link(oldname, newname string) error {
	return os.Link(fixpath(oldname), fixpath(newname))
}

// Stat returns a FileInfo structure describing the named file.
// If there is an error, it will be of type *PathError.
func Stat(name string) (os.FileInfo, error) {
	return os.Stat(fixpath(name))
}

// Lstat returns the FileInfo structure describing the named file.
// If the file is a symbolic link, the returned FileInfo
// describes the symbolic link.  Lstat makes no attempt to follow the link.
// If there is an error, it will be of type *PathError.
func Lstat(name string) (os.FileInfo, error) {
	return os.Lstat(fixpath(name))
}

// Create creates the named file with mode 0666 (before umask), truncating
// it if it already exists. If successful, methods on the returned
// File can be used for I/O; the associated file descriptor has mode
// O_RDWR.
// If there is an error, it will be of type *PathError.
func Create(name string) (*os.File, error) {
	return os.Create(fixpath(name))
}

// Open opens a file for reading.
func Open(name string) (File, error) {
	return os.Open(fixpath(name))
}

// OpenFile is the generalized open call; most users will use Open
// or Create instead.  It opens the named file with specified flag
// (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
// methods on the returned File can be used for I/O.
// If there is an error, it will be of type *PathError.
func OpenFile(name string, flag int, perm os.FileMode) (*os.File, error) {
	return os.OpenFile(fixpath(name), flag, perm)
}

// Walk walks the file tree rooted at root, calling walkFn for each file or
// directory in the tree, including root. All errors that arise visiting files
// and directories are filtered by walkFn. The files are walked in lexical
// order, which makes the output deterministic but means that for very
// large directories Walk can be inefficient.
// Walk does not follow symbolic links.
func Walk(root string, walkFn filepath.WalkFunc) error {
	return filepath.Walk(fixpath(root), walkFn)
}

// RemoveIfExists removes a file, returning no error if it does not exist.
func RemoveIfExists(filename string) error {
	err := os.Remove(filename)
	if err != nil && os.IsNotExist(err) {
		err = nil
	}
	return err
}

// Chtimes changes the access and modification times of the named file,
// similar to the Unix utime() or utimes() functions.
//
// The underlying filesystem may truncate or round the values to a less
// precise time unit. If there is an error, it will be of type *PathError.
func Chtimes(name string, atime time.Time, mtime time.Time) error {
	return os.Chtimes(fixpath(name), atime, mtime)
}

// IsAccessDenied checks if the error is due to permission error.
func IsAccessDenied(err error) bool {
	return os.IsPermission(err)
}

// ResetPermissions resets the permissions of the file at the specified path
func ResetPermissions(path string) error {
	// Set the default file permissions
	if err := os.Chmod(fixpath(path), 0600); err != nil {
		return err
	}
	return nil
}

// Readdirnames returns a list of file in a directory. Flags are passed to fs.OpenFile. O_RDONLY is implied.
func Readdirnames(filesystem FS, dir string, flags int) ([]string, error) {
	f, err := filesystem.OpenFile(dir, O_RDONLY|flags, 0)
	if err != nil {
		return nil, fmt.Errorf("openfile for readdirnames failed: %w", err)
	}

	entries, err := f.Readdirnames(-1)
	if err != nil {
		_ = f.Close()
		return nil, fmt.Errorf("readdirnames %v failed: %w", dir, err)
	}

	err = f.Close()
	if err != nil {
		return nil, err
	}

	return entries, nil
}
