feat: implement dialog callback

flutter/lib/plugin/handlers.dart

@@ -1,5 +1,9 @@
+import 'dart:convert';
 import 'dart:ffi';
 
+import 'package:ffi/ffi.dart';
+import 'package:flutter_hbb/plugin/utils/dialogs.dart';
+
 abstract class NativeHandler {
   bool onEvent(Map<String, dynamic> evt);
 }
@@ -37,7 +41,13 @@ class NativeUiHandler extends NativeHandler {
   }
 
   void onSelectPeers(OnSelectPeersCallbackDart cb, int userData) async {
-    // TODO: design a UI interface to pick peers.
-    cb(0, Pointer.fromAddress(0), 0, Pointer.fromAddress(userData));
+    showPeerSelectionDialog(onPeersCallback: (peers) {
+      String json = jsonEncode(<String, dynamic> {
+        "peers": peers
+      });
+      final native = json.toNativeUtf8();
+      cb(0, native.cast(), native.length, Pointer.fromAddress(userData));
+      malloc.free(native);
+    });
   }
 }

flutter/lib/plugin/utils/dialogs.dart

@@ -0,0 +1,83 @@
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_hbb/common.dart';
+import 'package:flutter_hbb/models/platform_model.dart';
+import 'package:get/get.dart';
+
+void showPeerSelectionDialog(
+    {bool singleSelection = false,
+    required Function(List<String>) onPeersCallback}) {
+  final peers = bind.mainLoadRecentPeersSync();
+  if (peers.isEmpty) {
+    debugPrint("load recent peers sync failed.");
+    return;
+  }
+  Map<String, dynamic> map = jsonDecode(peers);
+  List<dynamic> peersList = map['peers'] ?? [];
+  final selected = List<String>.empty(growable: true);
+
+  submit() async {
+    onPeersCallback.call(selected);
+  }
+
+  gFFI.dialogManager.show((setState, close, context) {
+    return CustomAlertDialog(
+      title:
+          Text(translate(singleSelection ? "Select peers" : "Select a peer")),
+      content: SizedBox(
+        height: 300.0,
+        child: ListView.builder(
+          itemBuilder: (context, index) {
+            final Map<String, dynamic> peer = peersList[index];
+            final String platform = peer['platform'] ?? "";
+            final String id = peer['id'] ?? "";
+            final String alias = peer['alias'] ?? "";
+            return GestureDetector(
+              onTap: () {
+                setState(() {
+                  if (selected.contains(id)) {
+                    selected.remove(id);
+                  } else {
+                    selected.add(id);
+                  }
+                });
+              },
+              child: Container(
+                key: ValueKey(index),
+                height: 50.0,
+                decoration: BoxDecoration(
+                  color: Theme.of(context).highlightColor,
+                  borderRadius: BorderRadius.circular(12.0)
+                ),
+                padding: EdgeInsets.symmetric(horizontal: 16.0, vertical: 4.0),
+                margin: EdgeInsets.symmetric(vertical: 4.0),
+                child: Row(
+                  crossAxisAlignment: CrossAxisAlignment.center,
+                  mainAxisSize: MainAxisSize.max,
+                  children: [
+                    // platform
+                    SizedBox(width: 8.0,),
+                    Column(
+                      mainAxisAlignment: MainAxisAlignment.center,
+                      children: [
+                        getPlatformImage(platform, size: 34.0),
+                      ],
+                    ),
+                    SizedBox(width: 8.0,),
+                    // id/alias
+                    Expanded(child: Text(alias.isEmpty ? id : alias)),
+                  ],
+                ),
+              ),
+            );
+          },
+          itemCount: peersList.length,
+          itemExtent: 50.0,
+        ),
+      ),
+      onSubmit: submit,
+    );
+  });
+}