Implement thread list loading

lib/main.dart

@@ -1,9 +1,22 @@
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 import 'package:wind/newsgroup_list_view.dart';
 import 'package:wind/nntp_client.dart';
+import 'package:wind/thread_list_view.dart';
+import 'package:wind/thread_screen.dart';
+
+import 'thread_list_model.dart';
 
 void main() {
-  runApp(MyApp());
+  runApp(MultiProvider(providers: [
+    Provider<NNTPClient>(create: ((context) => NNTPClient("localhost:1120"))),
+    ChangeNotifierProxyProvider<NNTPClient, ThreadListModel>(
+        create: (context) => ThreadListModel(),
+        update: (context, client, model) {
+          model!.client = client;
+          return model;
+        }),
+  ], child: MyApp()));
 }
 
 class MyApp extends StatelessWidget {
@@ -16,6 +29,7 @@ class MyApp extends StatelessWidget {
         primarySwatch: Colors.indigo,
       ),
       home: MyHomePage(title: 'Wind'),
+      routes: {'/thread': (context) => ThreadScreen()},
     );
   }
 }
@@ -72,14 +86,15 @@ class _MyHomePageState extends State<MyHomePage> {
                       Expanded(
                           child: Builder(
                               builder: (context) =>
-                                  NewsgroupListView(nntpClient))),
+                                  NewsgroupListView(client: nntpClient))),
                     ],
                   ),
                 ),
                 const VerticalDivider(thickness: 1, width: 1),
                 Expanded(
                     child: Center(
-                  child: ThreadsListView(),
+                  child: Consumer<ThreadListModel>(
+                      builder: ((context, value, child) => ThreadListView())),
                 ))
               ],
             ),
@@ -87,67 +102,3 @@ class _MyHomePageState extends State<MyHomePage> {
         ));
   }
 }
-
-class ThreadsListView extends StatefulWidget {
-  @override
-  State<StatefulWidget> createState() => ThreadsListViewState();
-}
-
-class ThreadsListViewState extends State<ThreadsListView> {
-  String currentGroup = "no group selected";
-
-  @override
-  Widget build(BuildContext context) {
-    return Container(width: 640, child: Center(child: Text(currentGroup)));
-  }
-}
-
-class ThreadListItemView extends StatelessWidget {
-  @override
-  Widget build(BuildContext context) {
-    return Card(
-        elevation: 5,
-        child: InkWell(
-          splashColor: Colors.indigo.withAlpha(30),
-          onTap: () => {},
-          child: Column(
-            crossAxisAlignment: CrossAxisAlignment.start,
-            mainAxisSize: MainAxisSize.min,
-            children: [
-              Container(
-                child: Text(
-                  "A question for those who watched The Matrix in 1999.",
-                  style: TextStyle(fontWeight: FontWeight.bold, fontSize: 21),
-                ),
-                margin: EdgeInsets.only(top: 16, left: 16, right: 16),
-              ),
-              Container(
-                child: Row(
-                  children: [
-                    Text(
-                      "@sample_user",
-                      style: TextStyle(
-                          fontWeight: FontWeight.normal,
-                          color: Colors.blue,
-                          fontSize: 15),
-                    ),
-                    SizedBox(width: 5),
-                    Text(
-                      "14/04/22 Чтв 00:57:52",
-                      style: TextStyle(fontSize: 15),
-                    ),
-                  ],
-                ),
-                margin: EdgeInsets.only(top: 5, bottom: 2, left: 16, right: 16),
-              ),
-              Container(
-                child: Text(
-                    "So I'm 16 years old, and I finally watched the first Matrix movie yesterday, and I found it amazing. Everything about it was wonderful. Anyway, I watched it with my mom and she was gushing over it again, telling me about how it blew her away when she watched it in the theaters when it came out.\nAnd that inspired me to ask this question. To any of you in this subreddit who watched the movie when it was released, do you have any fond memories or stories about your experience in the theater that you can tell me about?\nI'd really like to hear them. 👍",
-                    style: TextStyle(fontSize: 17)),
-                margin: EdgeInsets.all(16),
-              )
-            ],
-          ),
-        ));
-  }
-}

lib/newsgroup_list_view.dart

@@ -1,10 +1,22 @@
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 import 'package:wind/nntp_client.dart';
+import 'package:wind/thread_list_model.dart';
+
+class NewsgroupListView extends StatefulWidget {
+  NewsgroupListView({Key? key, required this.client}) : super(key: key);
 
-class NewsgroupListView extends StatelessWidget {
   final NNTPClient client;
 
-  NewsgroupListView(this.client);
+  @override
+  State<StatefulWidget> createState() => new NewsgroupListViewState(client);
+}
+
+class NewsgroupListViewState extends State<NewsgroupListView> {
+  late NNTPClient client;
+  int _selectedIndex = -1;
+
+  NewsgroupListViewState(this.client);
 
   @override
   Widget build(BuildContext context) {
@@ -13,7 +25,7 @@ class NewsgroupListView extends StatelessWidget {
       builder: (context, snapshot) {
         if (snapshot.hasData) {
           List<GroupInfo> data = snapshot.data!;
-          return _newgroupListView(data);
+          return _newsgroupListView(data);
         } else if (snapshot.hasError) {
           return Text("${snapshot.error}");
         }
@@ -26,7 +38,7 @@ class NewsgroupListView extends StatelessWidget {
     return await client.getNewsGroupList();
   }
 
-  ListView _newgroupListView(List<GroupInfo> data) {
+  Widget _newsgroupListView(List<GroupInfo> data) {
     return ListView.builder(
         itemCount: data.length,
         itemBuilder: (context, index) {
@@ -34,8 +46,14 @@ class NewsgroupListView extends StatelessWidget {
               style: ListTileStyle.drawer,
               title: Text(data[index].name),
               subtitle: Text(data[index].description),
-            onTap: () => {});
+              selected: index == _selectedIndex,
-      },
+              onTap: () {
-    );
+                setState(() => _selectedIndex = index);
+                var model = context.read<ThreadListModel>();
+                model
+                    .selectNewsgroup(data[index].name)
+                    .whenComplete(() => null);
+              });
+        });
   }
 }

lib/nntp_client.dart

@@ -1,10 +1,15 @@
 import 'dart:async';
 import 'dart:collection';
+import 'package:enough_mail/mime_message.dart';
 import 'package:web_socket_channel/web_socket_channel.dart';
+import 'package:tuple/tuple.dart';
 
 class NNTPClient {
   late WebSocketChannel _channel;
   final Queue<_NNTPCommand> commandQueue = new Queue();
+  final List<String> tempBuffer = [];
+
+  String? currentGroup;
 
   NNTPClient(String addr) {
     _channel = WebSocketChannel.connect(
@@ -12,14 +17,30 @@ class NNTPClient {
     );
 
     _channel.stream.listen((data) {
-      if ((data as String).contains("201")) {
+      if ((data as String).startsWith("201")) {
         // skip welcome message
         return;
       }
-      var command = commandQueue.removeFirst();
       var resp = data.toString();
       var respLines = resp.split("\r\n");
-      respLines.removeWhere((element) => element == "");
+      if (respLines.last == "") respLines.removeLast(); // trailing empty line
+
+      if ((respLines.length > 1 || tempBuffer.isNotEmpty) &&
+          respLines.last.codeUnits.last != ".".codeUnits.first) {
+        // if it's multiline response and it doesn't contain dot in the end
+        // then looks like we need to wait for next message to concatenate with current msg
+        tempBuffer.add(resp);
+        return;
+      }
+
+      if (tempBuffer.isNotEmpty) {
+        tempBuffer.add(resp);
+        resp = tempBuffer.join();
+        respLines = resp.split("\r\n");
+        respLines.removeLast(); // trailing empty line
+        tempBuffer.clear();
+      }
+      var command = commandQueue.removeFirst();
       var respCode = int.parse(respLines[0].split(" ")[0]);
       command.responseCompleter.complete(_CommandResponse(respCode, respLines));
     });
@@ -76,6 +97,35 @@ class NNTPClient {
 
     return l;
   }
+
+  Future<void> selectGroup(String name) async {
+    await _sendCommand("GROUP", [name]).then((value) => {currentGroup = name});
+  }
+
+  Future<List<Tuple2<int, MimeMessage>>> getNewThreads(
+      int perPage, int pageNum) async {
+    if (currentGroup == null) throw new ArgumentError("current group is null");
+
+    List<Tuple2<int, MimeMessage>> threads = [];
+
+    var newThreadList = await _sendCommand(
+        "NEWTHREADS", [perPage.toString(), pageNum.toString()]);
+
+    newThreadList.lines.removeAt(0);
+    newThreadList.lines.removeLast(); // remove dot
+
+    await Future.forEach<String>(newThreadList.lines, (element) async {
+      await _sendCommand("ARTICLE", [element]).then((response) {
+        response.lines.removeAt(0);
+        response.lines.removeLast();
+        var rawMsg = response.lines.join("\r\n");
+        threads
+            .add(Tuple2(int.parse(element), MimeMessage.parseFromText(rawMsg)));
+      });
+    });
+
+    return threads;
+  }
 }
 
 class _NNTPCommand {

lib/thread_list_model.dart

@@ -0,0 +1,50 @@
+import 'package:flutter/cupertino.dart';
+import 'package:wind/nntp_client.dart';
+import 'package:wind/thread_list_view.dart';
+
+class ThreadListModel extends ChangeNotifier {
+  String currentGroup = "";
+  NNTPClient? client;
+  Map<String, Map<int, List<ThreadItem>>> threads = {};
+
+  Future<void> selectNewsgroup(String name) async {
+    if (currentGroup == name) return;
+
+    currentGroup = name;
+    await client!.selectGroup(name);
+    threads.putIfAbsent(name, () => {});
+
+    notifyListeners();
+  }
+
+  Future<List<ThreadItem>> getNewThreads(
+      int perPage, int pageNum, bool clearCache) async {
+    if (currentGroup == "") return [];
+    List<ThreadItem> items = [];
+
+    if (clearCache) {
+      threads[currentGroup]?.clear();
+    }
+
+    if (threads[currentGroup]!.containsKey(pageNum)) {
+      items.addAll(threads[currentGroup]![pageNum]!);
+    } else {
+      var resp = await client!.getNewThreads(perPage, pageNum);
+      resp.forEach((pair) {
+        var number = pair.item1;
+        var msg = pair.item2;
+        items.add(ThreadItem(
+            msg.getHeaderValue("Message-Id")!,
+            number,
+            msg.getHeaderValue("Subject")!,
+            msg.getHeaderValue("From")!,
+            msg.getHeaderValue("Date")!,
+            msg.decodeTextPlainPart()!));
+      });
+
+      threads[currentGroup]![pageNum] = items;
+    }
+
+    return items;
+  }
+}

lib/thread_list_view.dart

@@ -0,0 +1,150 @@
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import 'package:wind/thread_list_model.dart';
+
+class ThreadListView extends StatefulWidget {
+  @override
+  State<StatefulWidget> createState() => ThreadListViewState();
+}
+
+class ThreadListViewState extends State<ThreadListView> {
+  List<ThreadItem> _items = [];
+  int _pageNum = 0;
+  String _curGroup = "";
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+        width: 640,
+        padding: EdgeInsets.only(top: 16),
+        child: FutureBuilder<List<ThreadItem>>(
+          future: _fetchThreadList(context),
+          builder: (context, snapshot) {
+            if (snapshot.hasData &&
+                snapshot.connectionState != ConnectionState.waiting) {
+              List<ThreadItem> data = List.from(snapshot.data!);
+              _items.addAll(data);
+              if (_items.isNotEmpty &&
+                  _items.last.number != -100500 &&
+                  data.isNotEmpty)
+                _items.add(ThreadItem("", -100500, "", "", "",
+                    "")); // magic item (for button "load more")
+              return _curGroup != ""
+                  ? _threadView()
+                  : Center(
+                      child: Text("Newsgroup is not selected",
+                          style: TextStyle(
+                              fontWeight: FontWeight.bold, fontSize: 16)));
+            } else if (snapshot.hasError) {
+              return Text("${snapshot.error}");
+            }
+            return Center(child: CircularProgressIndicator());
+          },
+        ));
+  }
+
+  Future<List<ThreadItem>> _fetchThreadList(BuildContext context) async {
+    var model = context.read<ThreadListModel>();
+    if (model.currentGroup != _curGroup) {
+      _items.clear();
+      _curGroup = model.currentGroup;
+      _pageNum = 0;
+    }
+    return await model.getNewThreads(10, _pageNum, false);
+  }
+
+  Widget _threadView() {
+    return _items.isNotEmpty
+        ? ListView.builder(
+            itemCount: _items.length,
+            itemBuilder: (context, index) {
+              if (_items[index].number == -100500) {
+                return Container(
+                  height: 100,
+                  padding: EdgeInsets.all(20),
+                  child: TextButton(
+                    style: ButtonStyle(
+                      foregroundColor:
+                          MaterialStateProperty.all<Color>(Colors.blue),
+                    ),
+                    onPressed: () {
+                      setState(() {
+                        _pageNum += 1;
+                        _items.removeLast();
+                      });
+                    },
+                    child: Text('Load more'),
+                  ),
+                );
+              } else
+                return ThreadListItemView(item: _items[index]);
+            })
+        : Center(
+            child: Text("This newsgroup is empty",
+                style: TextStyle(fontWeight: FontWeight.bold, fontSize: 16)));
+  }
+}
+
+class ThreadListItemView extends StatelessWidget {
+  const ThreadListItemView({Key? key, required this.item}) : super(key: key);
+
+  final ThreadItem item;
+
+  @override
+  Widget build(BuildContext context) {
+    return Card(
+        elevation: 5,
+        child: InkWell(
+          splashColor: Colors.indigo.withAlpha(30),
+          onTap: () => Navigator.pushNamed(context, "/thread"),
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              Container(
+                child: Text(
+                  item.subject,
+                  style: TextStyle(fontWeight: FontWeight.bold, fontSize: 21),
+                ),
+                margin: EdgeInsets.only(top: 16, left: 16, right: 16),
+              ),
+              Container(
+                child: Row(
+                  children: [
+                    Text(
+                      item.author,
+                      style: TextStyle(
+                          fontWeight: FontWeight.normal,
+                          color: Colors.blue,
+                          fontSize: 15),
+                    ),
+                    SizedBox(width: 5),
+                    Text(
+                      item.date,
+                      style: TextStyle(fontSize: 15),
+                    ),
+                  ],
+                ),
+                margin: EdgeInsets.only(top: 5, bottom: 2, left: 16, right: 16),
+              ),
+              Container(
+                child: Text(item.body, style: TextStyle(fontSize: 17)),
+                margin: EdgeInsets.all(16),
+              )
+            ],
+          ),
+        ));
+  }
+}
+
+class ThreadItem {
+  final String id;
+  final int number;
+  final String subject;
+  final String author;
+  final String date;
+  final String body;
+
+  ThreadItem(
+      this.id, this.number, this.subject, this.author, this.date, this.body);
+}

lib/thread_screen.dart

@@ -0,0 +1,17 @@
+import 'package:flutter/material.dart';
+
+class ThreadScreen extends StatefulWidget {
+  @override
+  State<StatefulWidget> createState() => ThreadScreenState();
+}
+
+class ThreadScreenState extends State<ThreadScreen> {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text("Thread"),
+      ),
+    );
+  }
+}

pubspec.lock

@@ -1,6 +1,20 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
+  args:
+    dependency: transitive
+    description:
+      name: args
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.3.0"
+  asn1lib:
+    dependency: transitive
+    description:
+      name: asn1lib
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   async:
     dependency: transitive
     description:
@@ -8,6 +22,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.9.0"
+  basic_utils:
+    dependency: transitive
+    description:
+      name: basic_utils
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.9.4"
   boolean_selector:
     dependency: transitive
     description:
@@ -43,6 +64,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.16.0"
+  convert:
+    dependency: transitive
+    description:
+      name: convert
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.0.1"
   crypto:
     dependency: transitive
     description:
@@ -57,6 +85,41 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.0.4"
+  encrypt:
+    dependency: transitive
+    description:
+      name: encrypt
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "5.0.1"
+  enough_convert:
+    dependency: transitive
+    description:
+      name: enough_convert
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.4.0"
+  enough_mail:
+    dependency: "direct main"
+    description:
+      name: enough_mail
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.6"
+  enough_serialization:
+    dependency: transitive
+    description:
+      name: enough_serialization
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.4.0"
+  event_bus:
+    dependency: transitive
+    description:
+      name: event_bus
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
   fake_async:
     dependency: transitive
     description:
@@ -74,6 +137,48 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  http:
+    dependency: transitive
+    description:
+      name: http
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.13.4"
+  http_parser:
+    dependency: transitive
+    description:
+      name: http_parser
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "4.0.0"
+  intl:
+    dependency: transitive
+    description:
+      name: intl
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.17.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.6.4"
+  json_annotation:
+    dependency: transitive
+    description:
+      name: json_annotation
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "4.4.0"
+  logging:
+    dependency: transitive
+    description:
+      name: logging
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.2"
   matcher:
     dependency: transitive
     description:
@@ -95,6 +200,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.7.0"
+  nested:
+    dependency: transitive
+    description:
+      name: nested
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
   path:
     dependency: transitive
     description:
@@ -102,6 +214,41 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.8.1"
+  pedantic:
+    dependency: transitive
+    description:
+      name: pedantic
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.11.1"
+  petitparser:
+    dependency: transitive
+    description:
+      name: petitparser
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "5.0.0"
+  pointycastle:
+    dependency: transitive
+    description:
+      name: pointycastle
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.5.2"
+  provider:
+    dependency: "direct main"
+    description:
+      name: provider
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "6.0.2"
+  quiver:
+    dependency: transitive
+    description:
+      name: quiver
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.0.1+1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -149,6 +296,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.4.9"
+  tuple:
+    dependency: "direct main"
+    description:
+      name: tuple
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
   typed_data:
     dependency: transitive
     description:
@@ -170,5 +324,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.1.0"
+  xml:
+    dependency: transitive
+    description:
+      name: xml
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "5.4.1"
 sdks:
   dart: ">=2.17.0-0 <3.0.0"
+  flutter: ">=1.16.0"

pubspec.yaml

@@ -29,6 +29,9 @@ dependencies:
   # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.2
   web_socket_channel: ^2.1.0
+  provider: ^6.0.2
+  enough_mail: ^1.3.6
+  tuple: ^2.0.0
 
 dev_dependencies:
   flutter_test: