Add menu command to move or rename document

docs/command-reference.md

@@ -189,6 +189,7 @@ Menu Commands
 | quit                         | q         |
 | force quit                   | q!        |
 | new document                 |           |
+| move or rename document      |           |
 | save document                | s, w      |
 | save document and quit       | sq, wq, x |
 | force save document          | s!, w!    |

input/actions.go

@@ -915,6 +915,15 @@ func ShowNewDocumentTextField(s *state.EditorState) {
 	})
 }
 
+func ShowMoveOrRenameDocumentTextField(s *state.EditorState) {
+	state.AbortIfUnsavedChanges(s, state.DefaultUnsavedChangesAbortMsg, func(s *state.EditorState) {
+		state.ShowTextField(s,
+			"Move/rename document file path:",
+			state.RenameDocument,
+			file.AutocompleteDirectory)
+	})
+}
+
 func AppendRuneToTextField(r rune) Action {
 	return func(s *state.EditorState) {
 		state.AppendRuneToTextField(s, r)

input/menu.go

@@ -25,6 +25,10 @@ func menuItems(ctx Context) []menu.Item {
 			Name:   "new document",
 			Action: ShowNewDocumentTextField,
 		},
+		{
+			Name:   "move or rename document",
+			Action: ShowMoveOrRenameDocumentTextField,
+		},
 		{
 			Name:    "save document",
 			Aliases: []string{"s", "w"},

state/document.go

@@ -35,6 +35,37 @@ func NewDocument(state *EditorState, path string) error {
 	return nil
 }
 
+// RenameDocument moves a document to a different file path.
+// Returns an error if the file already exists or the directory doesn't exist.
+func RenameDocument(state *EditorState, newPath string) error {
+	// Validate that we can create a file at the new path.
+	// This isn't 100% reliable, since some other process could create a file
+	// at the target path between this check and the rename below, but it at least
+	// reduces the risk of overwriting another file.
+	err := file.ValidateCreate(newPath)
+	if err != nil {
+		return err
+	}
+
+	// Move the file on disk. Ignore fs.ErrNotExist which can happen if
+	// the file was never saved to the old path.
+	//
+	// The rename won't trigger a reload of the old document because:
+	// 1. file.Watcher's check loop ignores fs.ErrNotExist.
+	// 2. LoadDocument below starts a new file watcher, so the main event loop
+	//    won't check the old file.Watcher's changed channel anyway.
+	oldPath := state.fileWatcher.Path()
+	err = os.Rename(oldPath, newPath)
+	if err != nil && !errors.Is(err, fs.ErrNotExist) {
+		return err
+	}
+
+	// Load the document at the new path, retaining the original cursor position.
+	cursorPos := state.documentBuffer.cursor.position
+	LoadDocument(state, newPath, false, func(_ LocatorParams) uint64 { return cursorPos })
+	return nil
+}
+
 // LoadDocument loads a file into the editor.
 func LoadDocument(state *EditorState, path string, requireExists bool, cursorLoc Locator) {
 	timelineState := currentTimelineState(state)

state/document_test.go

@@ -554,3 +554,49 @@ func TestNewDocumentFileAlreadyExists(t *testing.T) {
 	err := NewDocument(state, path)
 	assert.ErrorContains(t, err, "File already exists")
 }
+
+func TestRenameDocument(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "before.txt")
+	_, err := os.Create(path)
+	require.NoError(t, err)
+
+	state := NewEditorState(100, 100, nil, nil)
+	defer state.fileWatcher.Stop()
+	LoadDocument(state, path, true, startOfDocLocator)
+
+	newPath := filepath.Join(filepath.Dir(path), "renamed.txt")
+	err = RenameDocument(state, newPath)
+	require.NoError(t, err)
+	assert.Equal(t, newPath, state.FileWatcher().Path())
+}
+
+func TestRenameDocumentSrcFileNotSaved(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "test.txt")
+
+	state := NewEditorState(100, 100, nil, nil)
+	defer state.fileWatcher.Stop()
+	LoadDocument(state, path, true, startOfDocLocator)
+
+	newPath := filepath.Join(filepath.Dir(path), "renamed.txt")
+	err := RenameDocument(state, newPath)
+	require.NoError(t, err)
+	assert.Equal(t, newPath, state.FileWatcher().Path())
+}
+
+func TestRenameDocumentDestFileAlreadyExists(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "test.txt")
+
+	state := NewEditorState(100, 100, nil, nil)
+	defer state.fileWatcher.Stop()
+	LoadDocument(state, path, true, startOfDocLocator)
+
+	newPath := filepath.Join(filepath.Dir(path), "renamed.txt")
+	_, err := os.Create(newPath)
+	require.NoError(t, err)
+
+	err = RenameDocument(state, newPath)
+	assert.ErrorContains(t, err, "File already exists")
+}