"path"
	"slices"
	"strings"
	"testing"
)

var globTests = []struct {
	fs              FS
	pattern, result string
}{
	{os.DirFS("."), "glob.go", "glob.go"},
	{os.DirFS("."), "gl?b.go", "glob.go"},
	{os.DirFS("."), `gl\ob.go`, "glob.go"},
	{os.DirFS("."), "*", "glob.go"},
	{os.DirFS(".."), "*/glob.go", "fs/glob.go"},
}

func TestGlob(t *testing.T) {
	for _, tt := range globTests {

// [io/fs.ReadDirFS].
func DirFS(dir string) fs.FS {
	return dirFS(dir)
}

type dirFS string

func (dir dirFS) Open(name string) (fs.File, error) {
	fullname, err := dir.join(name)
	if err != nil {
		return nil, &PathError{Op: "open", Path: name, Err: err}
	}
	f, err := Open(fullname)
	if err != nil {
		// DirFS takes a string appropriate for GOOS,

	if !*flagCheck {
		t.Skip("-check not specified")
	}
	root := testenv.GOROOT(t)
	rootFS := os.DirFS(root)
	files, err := fs.Glob(rootFS, "api/next/*.txt")
	if err != nil {
		t.Fatal(err)
	}
	t.Logf("checking release notes for %d files in api/next", len(files))
	docFS := os.DirFS(filepath.Join(root, "doc", "next"))
	// Check that each api/next file has a corresponding release note fragment.

//
// Note that Sub(os.DirFS("/"), "prefix") is equivalent to os.DirFS("/prefix")
// and that neither of them guarantees to avoid operating system
// accesses outside "/prefix", because the implementation of [os.DirFS]
// does not check for symbolic links inside "/prefix" that point to
// other directories. That is, [os.DirFS] is not a general substitute for a

	// Test that Open can open a path starting at /.
	d := DirFS("/")
	f, err := d.Open(cwd + "/testdata/dirfs/a")
	if err != nil {
		t.Fatal(err)
	}
	f.Close()
}

func TestDirFSEmptyDir(t *testing.T) {
	t.Parallel()

	d := DirFS("")
	cwd, _ := Getwd()
	for _, path := range []string{
		"testdata/dirfs/a",                          // not DirFS(".")

	if string(data) != "hello, world" || err != nil {
		t.Fatalf(`ReadFile(sub(.), "hello.txt") = %q, %v, want %q, nil`, data, err, "hello, world")
	}
}

func TestReadFilePath(t *testing.T) {
	fsys := os.DirFS(t.TempDir())
	_, err1 := ReadFile(fsys, "non-existent")
	_, err2 := ReadFile(struct{ FS }{fsys}, "non-existent")
	if s1, s2 := errorPath(err1), errorPath(err2); s1 != s2 {
		t.Fatalf("s1: %s != s2: %s", s1, s2)
	}

var FS embed.FS

// BuiltinOrDir returns a FS for the provided directory. If no directory is passed, the compiled in
// FS will be used
func BuiltinOrDir(dir string) fs.FS {
	if dir == "" {
		return FS
	}
	return os.DirFS(dir)

	"errors"
	"internal/testenv"
	"io/fs"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"testing"
)

func TestSymlink(t *testing.T) {
	testenv.MustHaveSymlink(t)

	tmp := t.TempDir()
	tmpfs := os.DirFS(tmp)

	if err := os.WriteFile(filepath.Join(tmp, "hello"), []byte("hello, world\n"), 0644); err != nil {
		t.Fatal(err)
	}

	if err := os.Symlink(filepath.Join(tmp, "hello"), filepath.Join(tmp, "hello.link")); err != nil {

		}
	}
	bad := filepath.Join(dir, "a", "bad")
	if err := os.Chmod(bad, 0); err != nil {
		t.Fatal(err)
	}
	defer os.Chmod(bad, 0700) // avoid errors on cleanup
	var saw []string
	err := WalkDir(os.DirFS(dir), ".", func(path string, d DirEntry, err error) error {
		if err != nil {
			return filepath.SkipDir
		}
		if d.IsDir() {
			saw = append(saw, path)
		}
		return nil
	})
	if err != nil {

		})
	}
}

func errorPath(err error) string {
	var perr *PathError
	if !errors.As(err, &perr) {
		return ""
	}
	return perr.Path
}

func TestReadDirPath(t *testing.T) {
	fsys := os.DirFS(t.TempDir())
	_, err1 := ReadDir(fsys, "non-existent")
	_, err2 := ReadDir(struct{ FS }{fsys}, "non-existent")
	if s1, s2 := errorPath(err1), errorPath(err2); s1 != s2 {
		t.Fatalf("s1: %s != s2: %s", s1, s2)
	}