Rename top level directories

mobile/lib/selectors/files.dart

@@ -0,0 +1,162 @@
+import 'package:flutter/material.dart';
+
+import '../backend.dart';
+import '../platform.dart';
+
+/// Result of the user's interaction with the files selector.
+///
+/// This will be given back when popping the navigator.
+class FilesSelectorResult {
+  /// Document ID of the parent directory of the selected files.
+  ///
+  /// This will be null, if they are in the toplevel directory.
+  final String parentId;
+
+  /// Selected files.
+  final Set<Document> selection;
+
+  FilesSelectorResult(this.parentId, this.selection);
+}
+
+class FilesSelector extends StatefulWidget {
+  @override
+  _FilesSelectorState createState() => _FilesSelectorState();
+}
+
+class _FilesSelectorState extends State<FilesSelector> {
+  BackendState backend;
+  List<Document> history = [];
+  List<Document> children = [];
+  Set<Document> selection = {};
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+
+    backend = Backend.of(context);
+    loadChildren();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return WillPopScope(
+      child: Scaffold(
+        appBar: AppBar(
+          title: Text('Choose files'),
+          leading: IconButton(
+            icon: const Icon(Icons.close),
+            onPressed: () {
+              Navigator.pop(context);
+            },
+          ),
+          actions: <Widget>[
+            FlatButton(
+              child: Text('DONE'),
+              onPressed: () {
+                Navigator.pop(
+                  context,
+                  FilesSelectorResult(
+                    history.isNotEmpty ? history.last.id : null,
+                    selection,
+                  ),
+                );
+              },
+            ),
+          ],
+        ),
+        body: Column(
+          children: <Widget>[
+            Material(
+              elevation: 2.0,
+              child: ListTile(
+                leading: IconButton(
+                  icon: const Icon(Icons.arrow_upward),
+                  onPressed: history.isNotEmpty ? up : null,
+                ),
+                title: Text(
+                    history.isNotEmpty ? history.last.name : 'Music library'),
+              ),
+            ),
+            Expanded(
+              child: ListView.builder(
+                itemCount: children.length,
+                itemBuilder: (context, index) {
+                  final document = children[index];
+
+                  if (document.isDirectory) {
+                    return ListTile(
+                      leading: const Icon(Icons.folder),
+                      title: Text(document.name),
+                      onTap: () {
+                        setState(() {
+                          history.add(document);
+                        });
+                        loadChildren();
+                      },
+                    );
+                  } else {
+                    return CheckboxListTile(
+                      controlAffinity: ListTileControlAffinity.trailing,
+                      secondary: const Icon(Icons.insert_drive_file),
+                      title: Text(document.name),
+                      value: selection.contains(document),
+                      onChanged: (selected) {
+                        setState(() {
+                          if (selected) {
+                            selection.add(document);
+                          } else {
+                            selection.remove(document);
+                          }
+                        });
+                      },
+                    );
+                  }
+                },
+              ),
+            ),
+          ],
+        ),
+      ),
+      onWillPop: () => Future.value(up()),
+    );
+  }
+
+  Future<void> loadChildren() async {
+    setState(() {
+      children = [];
+
+      // We reset the selection here, because the user should not be able to
+      // select files from multiple directories for now.
+      selection = {};
+    });
+
+    final newChildren = await Platform.getChildren(
+        backend.musicLibraryUri, history.isNotEmpty ? history.last.id : null);
+
+    newChildren.sort((d1, d2) {
+      if (d1.isDirectory != d2.isDirectory) {
+        return d1.isDirectory ? -1 : 1;
+      } else {
+        return d1.name.compareTo(d2.name);
+      }
+    });
+
+    setState(() {
+      children = newChildren;
+    });
+  }
+
+  bool up() {
+    if (history.isNotEmpty) {
+      setState(() {
+        history.removeLast();
+      });
+
+      loadChildren();
+
+      return false;
+    } else {
+      return true;
+    }
+  }
+}