Allow folders to be renamed

This is a huge change which involves -
* Implementing Folder renames on the FS + Git level
* Implementing the concept of selecting an item in the FoldersListView,
  this feature isn't provided by default, and even now I'm not sure if
  the semantics which I've implemented are correct. I haven't
  implemented multiple folder selection for now.

Related to issue #18

Also, we're now one step closer to allowing notes to be renamed (#23)

lib/core/notes_folder.dart

@@ -144,4 +144,12 @@ class NotesFolder with ChangeNotifier {
 
     notifyListeners();
   }
+
+  void rename(String newName) {
+    var dir = Directory(folderPath);
+    var parentDirName = dirname(folderPath);
+    var newFullPath = p.join(parentDirName, newName);
+
+    dir.renameSync(newFullPath);
+  }
 }

lib/screens/folder_listing.dart

@@ -8,7 +8,14 @@ import 'package:gitjournal/core/notes_folder.dart';
 
 import 'journal_listing.dart';
 
-class FolderListingScreen extends StatelessWidget {
+class FolderListingScreen extends StatefulWidget {
+  @override
+  _FolderListingScreenState createState() => _FolderListingScreenState();
+}
+
+class _FolderListingScreenState extends State<FolderListingScreen> {
+  NotesFolder selectedFolder;
+
   @override
   Widget build(BuildContext context) {
     final container = StateContainer.of(context);
@@ -16,7 +23,7 @@ class FolderListingScreen extends StatelessWidget {
 
     var treeView = FolderTreeView(
       rootFolder: appState.notesFolder,
-      onFolderSelected: (NotesFolder folder) {
+      onFolderEntered: (NotesFolder folder) {
         var route = MaterialPageRoute(
           builder: (context) => JournalListingScreen(
             notesFolder: folder,
@@ -24,12 +31,49 @@ class FolderListingScreen extends StatelessWidget {
         );
         Navigator.of(context).push(route);
       },
+      onFolderSelected: (folder) {
+        setState(() {
+          selectedFolder = folder;
+        });
+      },
+      onFolderUnselected: () {
+        setState(() {
+          selectedFolder = null;
+        });
+      },
     );
 
+    Widget action;
+    if (selectedFolder != null) {
+      action = PopupMenuButton(
+        itemBuilder: (context) {
+          return [
+            PopupMenuItem<String>(
+              child: const Text("Rename Folder"),
+              value: "Rename Folder",
+            )
+          ];
+        },
+        onSelected: (String _) async {
+          var folderName = await showDialog(
+            context: context,
+            builder: (_) => RenameFolderDialog(selectedFolder),
+          );
+          if (folderName is String) {
+            final container = StateContainer.of(context);
+            container.renameFolder(selectedFolder, folderName);
+          }
+        },
+      );
+    }
+
     return Scaffold(
       appBar: AppBar(
         title: const Text('Folders'),
         leading: GJAppBarMenuButton(),
+        actions: <Widget>[
+          if (selectedFolder != null) action,
+        ],
       ),
       body: treeView,
       drawer: AppDrawer(),
@@ -109,3 +153,67 @@ class _CreateFolderButtonState extends State<CreateFolderButton> {
     );
   }
 }
+
+class RenameFolderDialog extends StatefulWidget {
+  final NotesFolder folder;
+
+  RenameFolderDialog(this.folder);
+
+  @override
+  _RenameFolderDialogState createState() => _RenameFolderDialogState();
+}
+
+class _RenameFolderDialogState extends State<RenameFolderDialog> {
+  TextEditingController _textController;
+
+  @override
+  void initState() {
+    super.initState();
+    _textController = TextEditingController(text: widget.folder.name);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    var form = Form(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: <Widget>[
+          TextFormField(
+            decoration: const InputDecoration(labelText: 'Folder Name'),
+            validator: (value) {
+              if (value.isEmpty) return 'Please enter a name';
+              return "";
+            },
+            autofocus: true,
+            keyboardType: TextInputType.text,
+            controller: _textController,
+          ),
+        ],
+      ),
+    );
+
+    return AlertDialog(
+      title: const Text("Rename Folder"),
+      actions: <Widget>[
+        FlatButton(
+          onPressed: () => Navigator.of(context).pop(false),
+          child: const Text("Cancel"),
+        ),
+        FlatButton(
+          onPressed: () {
+            var newFolderName = _textController.text;
+            return Navigator.of(context).pop(newFolderName);
+          },
+          child: const Text("Rename"),
+        ),
+      ],
+      content: form,
+    );
+  }
+
+  @override
+  void dispose() {
+    _textController.dispose();
+    super.dispose();
+  }
+}

lib/state_container.dart

@@ -160,6 +160,21 @@ class StateContainerState extends State<StateContainer> {
     });
   }
 
+  void renameFolder(NotesFolder folder, String newFolderName) async {
+    var oldFolderPath = folder.folderPath;
+
+    setState(() {
+      folder.rename(newFolderName);
+
+      // Update the git repo
+      noteRepo
+          .renameFolder(oldFolderPath, folder.folderPath)
+          .then((NoteRepoResult _) {
+        _syncNotes();
+      });
+    });
+  }
+
   void addNote(Note note) {
     insertNote(0, note);
   }

lib/storage/git_storage.dart

@@ -60,6 +60,19 @@ class GitNoteRepository {
     return NoteRepoResult(noteFilePath: folder.folderPath, error: false);
   }
 
+  Future<NoteRepoResult> renameFolder(
+    String oldFullPath,
+    String newFullPath,
+  ) async {
+    // FIXME: This is a hacky way of adding the changes, ideally we should be calling rm + add or something
+    await _gitRepo.add(".");
+    await _gitRepo.commit(
+      message: "Renamed folder",
+    );
+
+    return NoteRepoResult(noteFilePath: newFullPath, error: false);
+  }
+
   Future<NoteRepoResult> removeNote(String noteFilePath) async {
     var gitDir = p.join(baseDirectory, dirName);
     var pathSpec = noteFilePath.replaceFirst(gitDir, "").substring(1);

lib/widgets/folder_tree_view.dart

@@ -4,30 +4,71 @@ import 'package:gitjournal/core/notes_folder.dart';
 
 typedef void FolderSelectedCallback(NotesFolder folder);
 
-class FolderTreeView extends StatelessWidget {
+class FolderTreeView extends StatefulWidget {
   final NotesFolder rootFolder;
+
   final FolderSelectedCallback onFolderSelected;
+  final Function onFolderUnselected;
+  final FolderSelectedCallback onFolderEntered;
 
   FolderTreeView({
     @required this.rootFolder,
     @required this.onFolderSelected,
+    @required this.onFolderUnselected,
+    @required this.onFolderEntered,
   });
 
+  @override
+  _FolderTreeViewState createState() => _FolderTreeViewState();
+}
+
+class _FolderTreeViewState extends State<FolderTreeView> {
+  bool inSelectionMode = false;
+  NotesFolder selectedFolder;
+
   @override
   Widget build(BuildContext context) {
+    var tile = FolderTile(
+      folder: widget.rootFolder,
+      onTap: (NotesFolder folder) {
+        if (!inSelectionMode) {
+          widget.onFolderEntered(folder);
+        } else {
+          setState(() {
+            inSelectionMode = false;
+            selectedFolder = null;
+          });
+          widget.onFolderUnselected();
+        }
+      },
+      onLongPress: (folder) {
+        setState(() {
+          inSelectionMode = true;
+          selectedFolder = folder;
+        });
+        widget.onFolderSelected(folder);
+      },
+      selectedFolder: selectedFolder,
+    );
+
     return ListView(
-      children: <Widget>[
+      children: <Widget>[tile],
-        FolderTile(rootFolder, onFolderSelected),
-      ],
     );
   }
 }
 
 class FolderTile extends StatefulWidget {
   final NotesFolder folder;
-  final FolderSelectedCallback onFolderSelected;
+  final FolderSelectedCallback onTap;
+  final FolderSelectedCallback onLongPress;
+  final NotesFolder selectedFolder;
 
-  FolderTile(this.folder, this.onFolderSelected);
+  FolderTile({
+    @required this.folder,
+    @required this.onTap,
+    @required this.onLongPress,
+    @required this.selectedFolder,
+  });
 
   @override
   FolderTileState createState() => FolderTileState();
@@ -49,7 +90,8 @@ class FolderTileState extends State<FolderTile> {
       children: <Widget>[
         GestureDetector(
           child: _buildFolderTile(),
-          onTap: () => widget.onFolderSelected(widget.folder),
+          onTap: () => widget.onTap(widget.folder),
+          onLongPress: () => widget.onLongPress(widget.folder),
         ),
         _getChild(),
       ],
@@ -72,6 +114,9 @@ class FolderTileState extends State<FolderTile> {
     }
     var subtitle = folder.numberOfNotes.toString() + " Notes";
 
+    final theme = Theme.of(context);
+
+    var selected = widget.selectedFolder == widget.folder;
     return Card(
       child: ListTile(
         leading: Container(
@@ -87,7 +132,9 @@ class FolderTileState extends State<FolderTile> {
         title: Text(folderName),
         subtitle: Text(subtitle),
         trailing: trailling,
+        selected: selected,
       ),
+      color: selected ? theme.selectedRowColor : theme.cardColor,
     );
   }
 
@@ -102,7 +149,12 @@ class FolderTileState extends State<FolderTile> {
 
     var children = <FolderTile>[];
     widget.folder.getFolders().forEach((folder) {
-      children.add(FolderTile(folder, widget.onFolderSelected));
+      children.add(FolderTile(
+        folder: folder,
+        onTap: widget.onTap,
+        onLongPress: widget.onLongPress,
+        selectedFolder: widget.selectedFolder,
+      ));
     });
 
     return Container(