new: sftp search (#345)

lib/view/widget/search.dart

@@ -0,0 +1,87 @@
+import 'package:flutter/material.dart';
+import 'package:toolbox/core/extension/context/common.dart';
+import 'package:toolbox/core/extension/context/locale.dart';
+import 'package:toolbox/data/res/ui.dart';
+import 'package:toolbox/view/widget/future_widget.dart';
+
+final class SearchPage<T> extends SearchDelegate<T> {
+  final Future<List<T>> Function(String) future;
+  final Widget Function(BuildContext, T) builder;
+  final EdgeInsetsGeometry? padding;
+  final Duration throttleInterval;
+
+  List<T> _cache = [];
+  DateTime? _lastSearch;
+
+  SearchPage({
+    required this.future,
+    required this.builder,
+    this.padding,
+    this.throttleInterval = const Duration(milliseconds: 200),
+  });
+
+  @override
+  List<Widget>? buildActions(BuildContext context) {
+    return [
+      IconButton(
+        icon: const Icon(Icons.clear),
+        onPressed: () {
+          query = '';
+        },
+      ),
+    ];
+  }
+
+  @override
+  Widget? buildLeading(BuildContext context) {
+    return IconButton(
+      onPressed: context.pop,
+      icon: const Icon(Icons.arrow_back),
+    );
+  }
+
+  @override
+  Widget buildResults(BuildContext context) {
+    return _buildList(context);
+  }
+
+  @override
+  Widget buildSuggestions(BuildContext context) {
+    return _buildList(context);
+  }
+
+  Widget _buildList(BuildContext context) {
+    return FutureWidget(
+      future: _search(query),
+      loading: const Center(child: UIs.centerSizedLoading),
+      error: (error, trace) {
+        return Center(
+          child: Text('$error\n$trace'),
+        );
+      },
+      success: (list) {
+        if (list == null || list.isEmpty) {
+          return Center(child: Text(l10n.noResult));
+        }
+
+        return ListView.builder(
+          padding: padding,
+          itemCount: list.length,
+          itemBuilder: (_, index) => builder(context, list[index]),
+        );
+      },
+    );
+  }
+
+  Future<List<T>> _search(String query) async {
+    final lastSearch = _lastSearch;
+    if (lastSearch != null) {
+      final now = DateTime.now();
+      if (now.difference(lastSearch) < throttleInterval) {
+        return _cache;
+      }
+    }
+    _cache = await future(query);
+    return _cache;
+  }
+}