package ctxbilly

import (
	"context"
	"io"
	"os"

	"github.com/royalcat/ctxio"
)

type Filesystem interface {
	// 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.
	Create(ctx context.Context, filename string) (File, error)
	// Open opens the named file for reading. If successful, methods on the
	// returned file can be used for reading; the associated file descriptor has
	// mode O_RDONLY.
	Open(ctx context.Context, filename string) (File, error)
	// 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.
	OpenFile(ctx context.Context, filename string, flag int, perm os.FileMode) (File, error)
	// Stat returns a FileInfo describing the named file.
	Stat(ctx context.Context, filename string) (os.FileInfo, error)
	// Rename renames (moves) oldpath to newpath. If newpath already exists and
	// is not a directory, Rename replaces it. OS-specific restrictions may
	// apply when oldpath and newpath are in different directories.
	Rename(ctx context.Context, oldpath, newpath string) error
	// Remove removes the named file or directory.
	Remove(ctx context.Context, filename string) error
	// Join joins any number of path elements into a single path, adding a
	// Separator if necessary. Join calls filepath.Clean on the result; in
	// particular, all empty strings are ignored. On Windows, the result is a
	// UNC path if and only if the first path element is a UNC path.
	Join(elem ...string) string

	// ReadDir reads the directory named by d(irname and returns a list of
	// directory entries sorted by filename.
	ReadDir(ctx context.Context, path string) ([]os.FileInfo, error)
	// 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.
	MkdirAll(ctx context.Context, filename string, perm os.FileMode) error

	// Lstat returns a FileInfo 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.
	Lstat(ctx context.Context, filename string) (os.FileInfo, error)
	// Symlink creates a symbolic-link from link to target. target may be an
	// absolute or relative path, and need not refer to an existing node.
	// Parent directories of link are created as necessary.
	Symlink(ctx context.Context, target, link string) error
	// Readlink returns the target path of link.
	Readlink(ctx context.Context, link string) (string, error)

	// // Chroot returns a new filesystem from the same type where the new root is
	// // the given path. Files outside of the designated directory tree cannot be
	// // accessed.
	// Chroot(path string) (Filesystem, error)
	// // Root returns the root path of the filesystem.
	// Root() string
}

type TempFileFS interface {
	// TempFile creates a new temporary file in the directory dir with a name
	// beginning with prefix, opens the file for reading and writing, and
	// returns the resulting *os.File. If dir is the empty string, TempFile
	// uses the default directory for temporary files (see os.TempDir).
	// Multiple programs calling TempFile simultaneously will not choose the
	// same file. The caller can use f.Name() to find the pathname of the file.
	// It is the caller's responsibility to remove the file when no longer
	// needed.
	TempFile(ctx context.Context, dir, prefix string) (File, error)
}

type File interface {
	// Name returns the name of the file as presented to Open.
	Name() string
	ctxio.Writer
	ctxio.WriterAt
	ctxio.Reader
	ctxio.ReaderAt
	io.Seeker
	ctxio.Closer
}

type LockFile interface {
	// Lock locks the file like e.g. flock. It protects against access from
	// other processes.
	Lock() error
	// Unlock unlocks the file.
	Unlock() error
}

type TruncateFile interface {
	// Truncate the file.
	Truncate(ctx context.Context, size int64) error
}