refactor: extract long list scaffold for issue and pull request

lib/main.dart

@@ -7,6 +7,8 @@ import 'screens/notifications.dart';
 import 'screens/search.dart';
 import 'screens/profile.dart';
 import 'screens/login.dart';
+import 'screens/pull_request.dart';
+import 'screens/issue.dart';
 
 class Home extends StatefulWidget {
   @override
@@ -58,6 +60,7 @@ class _HomeState extends State<Home> {
   }
 
   _buildScreen(int index) {
+    // return IssueScreen(number: 29, owner: 'reactjs', name: 'rfcs');
     switch (index) {
       case 0:
         return NewsScreen();

lib/screens/issue.dart

@@ -1,59 +1,44 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/cupertino.dart';
 import '../utils/utils.dart';
-import '../widgets/list_scaffold.dart';
+import '../widgets/long_list_scaffold.dart';
 import '../widgets/timeline_item.dart';
 import '../widgets/comment_item.dart';
 import '../providers/settings.dart';
 
 class IssueScreen extends StatefulWidget {
-  final int id;
+  final int number;
   final String owner;
   final String name;
 
-  IssueScreen(this.id, this.owner, this.name);
+  IssueScreen({
+    @required this.number,
+    @required this.owner,
+    @required this.name,
+  });
+
+  IssueScreen.fromFullName({@required this.number, @required String fullName})
+      : this.owner = fullName.split('/')[0],
+        this.name = fullName.split('/')[1];
 
   @override
   _IssueScreenState createState() => _IssueScreenState();
 }
 
 class _IssueScreenState extends State<IssueScreen> {
-  Map<String, dynamic> payload;
-
-  Widget _buildHeader() {
-    return Column(children: <Widget>[
-      Container(
-        // padding: EdgeInsets.all(10),
-        child: Column(
-          crossAxisAlignment: CrossAxisAlignment.start,
-          children: <Widget>[
-            Text(
-              payload['title'],
-              style: TextStyle(
-                fontSize: 18,
-                fontWeight: FontWeight.bold,
-                height: 1.2,
-              ),
-            ),
-            CommentItem(payload),
-          ],
-        ),
-      )
-    ]);
-  }
-
   get _fullName => widget.owner + '/' + widget.name;
+  get owner => widget.owner;
+  get id => widget.number;
+  get name => widget.name;
 
-  List get _items => payload == null ? [] : payload['timeline']['nodes'];
+  Future queryIssue() async {
-
-  Future queryIssue(
-      BuildContext context, int id, String owner, String name) async {
     var data = await SettingsProvider.of(context).query('''
 {
   repository(owner: "$owner", name: "$name") {
     issue(number: $id) {
       $graphqlChunk1
       timeline(first: $pageSize) {
+        totalCount
         pageInfo {
           hasNextPage
           endCursor
@@ -69,23 +54,104 @@ class _IssueScreenState extends State<IssueScreen> {
     return data['repository']['issue'];
   }
 
+  Future queryMore(String cursor) async {
+    var data = await SettingsProvider.of(context).query('''
+{
+  repository(owner: "$owner", name: "$name") {
+    issue(number: $id) {
+      timeline(first: $pageSize, after: $cursor) {
+        totalCount
+        pageInfo {
+          endCursor
+        }
+        nodes {
+          $graghqlChunk
+        }
+      }
+    }
+  }
+}
+''');
+    return data['repository']['issue'];
+  }
+
+  Future<List> queryTrailing() async {
+    var data = await SettingsProvider.of(context).query('''
+{
+  repository(owner: "$owner", name: "$name") {
+    issue(number: $id) {
+      timeline(last: $pageSize) {
+        nodes {
+          $graghqlChunk
+        }
+      }
+    }
+  }
+}
+''');
+    return data['repository']['issue']['timeline']['nodes'];
+  }
+
   @override
   Widget build(BuildContext context) {
-    return ListScaffold(
+    return LongListScaffold(
-      title: Text(_fullName + ' #' + widget.id.toString()),
+      title: Text(_fullName + ' #' + widget.number.toString()),
-      header: payload == null ? null : _buildHeader(),
+      headerBuilder: (payload) {
-      itemCount: _items.length,
+        return Column(children: <Widget>[
-      itemBuilder: (context, index) => TimelineItem(_items[index], payload),
+          Container(
-      onRefresh: () async {
+            // padding: EdgeInsets.all(10),
-        var _payload =
+            child: Column(
-            await queryIssue(context, widget.id, widget.owner, widget.name);
+              crossAxisAlignment: CrossAxisAlignment.start,
-        if (mounted) {
+              children: <Widget>[
-          setState(() {
+                Text(
-            payload = _payload;
+                  payload['title'],
-          });
+                  style: TextStyle(
-        }
+                    fontSize: 18,
+                    fontWeight: FontWeight.bold,
+                    height: 1.2,
+                  ),
+                ),
+                CommentItem(payload),
+              ],
+            ),
+          )
+        ]);
+      },
+      itemBuilder: (itemPayload) => TimelineItem(itemPayload),
+      onRefresh: () async {
+        var res = await queryIssue();
+        int totalCount = res['timeline']['totalCount'];
+        String cursor = res['timeline']['pageInfo']['endCursor'];
+        List leadingItems = res['timeline']['nodes'];
+
+        var payload = LongListPayload(
+          header: res,
+          totalCount: totalCount,
+          cursor: cursor,
+          leadingItems: leadingItems,
+          trailingItems: [],
+        );
+
+        if (totalCount > 2 * pageSize) {
+          payload.trailingItems = await queryTrailing();
+        }
+
+        return payload;
+      },
+      onLoadMore: (String _cursor) async {
+        var res = await queryMore(_cursor);
+        int totalCount = res['timeline']['totalCount'];
+        String cursor = res['timeline']['pageInfo']['endCursor'];
+        List leadingItems = res['timeline']['nodes'];
+
+        var payload = LongListPayload(
+          totalCount: totalCount,
+          cursor: cursor,
+          leadingItems: leadingItems,
+        );
+
+        return payload;
       },
-      // onLoadMore: () => ,
     );
   }
 }

lib/screens/pull_request.dart

@@ -2,29 +2,76 @@ import 'package:flutter/material.dart';
 import 'package:flutter/cupertino.dart';
 import '../providers/settings.dart';
 import '../utils/utils.dart';
-import '../widgets/list_scaffold.dart';
+import '../widgets/long_list_scaffold.dart';
 import '../widgets/timeline_item.dart';
 import '../widgets/comment_item.dart';
 
 class PullRequestScreen extends StatefulWidget {
-  final int id;
+  final int number;
   final String owner;
   final String name;
 
-  PullRequestScreen(this.id, this.owner, this.name);
+  PullRequestScreen({
+    @required this.number,
+    @required this.owner,
+    @required this.name,
+  });
+
+  PullRequestScreen.fromFullName(
+      {@required this.number, @required String fullName})
+      : this.owner = fullName.split('/')[0],
+        this.name = fullName.split('/')[1];
 
   @override
   _PullRequestScreenState createState() => _PullRequestScreenState();
 }
 
+var commonChunk = '''
+$graghqlChunk
+... on ReviewRequestedEvent {
+  createdAt
+  actor {
+    login
+  }
+  requestedReviewer {
+    ... on User {
+      login
+    }
+  }
+}
+... on PullRequestReview {
+  createdAt
+  state
+  author {
+    login
+  }
+}
+... on MergedEvent {
+  createdAt
+  mergeRefName
+  actor {
+    login
+  }
+  commit {
+    oid
+    url
+  }
+}
+... on HeadRefDeletedEvent {
+  createdAt
+  actor {
+    login
+  }
+  headRefName
+}
+''';
+
 class _PullRequestScreenState extends State<PullRequestScreen> {
-  Map<String, dynamic> payload;
+  get owner => widget.owner;
-
+  get id => widget.number;
-  Future queryPullRequest(BuildContext context) async {
+  get name => widget.name;
-    var owner = widget.owner;
-    var id = widget.id;
-    var name = widget.name;
 
+  Future queryPullRequest() async {
     var data = await SettingsProvider.of(context).query('''
 {
   repository(owner: "$owner", name: "$name") {
@@ -38,48 +85,12 @@ class _PullRequestScreenState extends State<PullRequestScreen> {
         totalCount
       }
       timeline(first: $pageSize) {
+        totalCount
         pageInfo {
-          hasNextPage
           endCursor
         }
         nodes {
-          $graghqlChunk
+          $commonChunk
-          ... on ReviewRequestedEvent {
-            createdAt
-            actor {
-              login
-            }
-            requestedReviewer {
-              ... on User {
-                login
-              }
-            }
-          }
-          ... on PullRequestReview {
-            createdAt
-            state
-            author {
-              login
-            }
-          }
-          ... on MergedEvent {
-            createdAt
-            mergeRefName
-            actor {
-              login
-            }
-            commit {
-              oid
-              url
-            }
-          }
-          ... on HeadRefDeletedEvent {
-            createdAt
-            actor {
-              login
-            }
-            headRefName
-          }
         }
       }
     }
@@ -89,7 +100,45 @@ class _PullRequestScreenState extends State<PullRequestScreen> {
     return data['repository']['pullRequest'];
   }
 
-  Widget _buildBadge() {
+  Future queryMore(String cursor) async {
+    var data = await SettingsProvider.of(context).query('''
+{
+  repository(owner: "$owner", name: "$name") {
+    pullRequest(number: $id) {
+      timeline(first: $pageSize, after: $cursor) {
+        totalCount
+        pageInfo {
+          endCursor
+        }
+        nodes {
+          $commonChunk
+        }
+      }
+    }
+  }
+}
+''');
+    return data['repository']['pullRequest'];
+  }
+
+  Future<List> queryTrailing() async {
+    var data = await SettingsProvider.of(context).query('''
+{
+  repository(owner: "$owner", name: "$name") {
+    pullRequest(number: $id) {
+      timeline(last: $pageSize) {
+        nodes {
+          $commonChunk
+        }
+      }
+    }
+  }
+}
+''');
+    return data['repository']['pullRequest']['timeline']['nodes'];
+  }
+
+  Widget _buildBadge(payload) {
     bool merged = payload['merged'];
     Color bgColor = merged ? Palette.purple : Palette.green;
     IconData iconData = merged ? Octicons.git_merge : Octicons.git_pull_request;
@@ -117,47 +166,67 @@ class _PullRequestScreenState extends State<PullRequestScreen> {
 
   get _fullName => widget.owner + '/' + widget.name;
 
-  Widget _buildHeader() {
-    return Column(children: <Widget>[
-      Container(
-        // padding: EdgeInsets.all(10),
-        child: Column(
-          crossAxisAlignment: CrossAxisAlignment.start,
-          children: <Widget>[
-            _buildBadge(),
-            Text(
-              payload['title'],
-              style: TextStyle(
-                fontSize: 18,
-                fontWeight: FontWeight.bold,
-                height: 1.2,
-              ),
-            ),
-            CommentItem(payload),
-          ],
-        ),
-      )
-    ]);
-  }
-
-  List get _items => payload == null ? [] : payload['timeline']['nodes'];
-
   @override
   Widget build(BuildContext context) {
-    return ListScaffold(
+    return LongListScaffold(
-      title: Text(_fullName + ' #' + widget.id.toString()),
+      title: Text(_fullName + ' #' + widget.number.toString()),
-      header: payload == null ? null : _buildHeader(),
+      headerBuilder: (payload) {
-      itemCount: _items.length,
+        return Column(children: <Widget>[
-      itemBuilder: (context, index) => TimelineItem(_items[index], payload),
+          Container(
-      onRefresh: () async {
+            // padding: EdgeInsets.all(10),
-        var _payload = await queryPullRequest(context);
+            child: Column(
-        if (mounted) {
+              crossAxisAlignment: CrossAxisAlignment.start,
-          setState(() {
+              children: <Widget>[
-            payload = _payload;
+                _buildBadge(payload),
-          });
+                Text(
-        }
+                  payload['title'],
+                  style: TextStyle(
+                    fontSize: 18,
+                    fontWeight: FontWeight.bold,
+                    height: 1.2,
+                  ),
+                ),
+                CommentItem(payload),
+              ],
+            ),
+          )
+        ]);
+      },
+      itemBuilder: (itemPayload) => TimelineItem(itemPayload),
+      onRefresh: () async {
+        var res = await queryPullRequest();
+        int totalCount = res['timeline']['totalCount'];
+        String cursor = res['timeline']['pageInfo']['endCursor'];
+        List leadingItems = res['timeline']['nodes'];
+
+        var payload = LongListPayload(
+          header: res,
+          totalCount: totalCount,
+          cursor: cursor,
+          leadingItems: leadingItems,
+          trailingItems: [],
+        );
+
+        if (totalCount > 2 * pageSize) {
+          payload.trailingItems = await queryTrailing();
+        }
+
+        return payload;
+      },
+      onLoadMore: (String _cursor) async {
+        var res = await queryMore(_cursor);
+        int totalCount = res['timeline']['totalCount'];
+        String cursor = res['timeline']['pageInfo']['endCursor'];
+        List leadingItems = res['timeline']['nodes'];
+
+        var payload = LongListPayload(
+          totalCount: totalCount,
+          cursor: cursor,
+          leadingItems: leadingItems,
+        );
+
+        return payload;
       },
-      // onLoadMore: () => ,
     );
   }
 }

lib/utils/utils.dart

@@ -154,7 +154,7 @@ class Palette {
   static const gray = Color(0xff959da5);
 }
 
-final pageSize = 20;
+final pageSize = 5;
 
 final graphqlChunk1 = '''
 title

lib/widgets/event_item.dart

@@ -19,17 +19,17 @@ class EventItem extends StatelessWidget {
 
   TextSpan _buildIssue(BuildContext context) {
     int id = event.payload['issue']['number'];
-    String name = event.repo.name;
+    return createLinkSpan(context, '#' + id.toString(),
-    var arr = name.split('/');
+        () => IssueScreen.fromFullName(number: id, fullName: event.repo.name));
-    return createLinkSpan(
-        context, '#' + id.toString(), () => IssueScreen(id, arr[0], arr[1]));
   }
 
-  TextSpan _buildPullRequest(BuildContext context, int id) {
+  TextSpan _buildPullRequest(BuildContext context, int number) {
-    String name = event.repo.name;
+    return createLinkSpan(
-    var arr = name.split('/');
+      context,
-    return createLinkSpan(context, '#' + id.toString(),
+      '#' + number.toString(),
-        () => PullRequestScreen(id, arr[0], arr[1]));
+      () => PullRequestScreen.fromFullName(
+          number: number, fullName: event.repo.name),
+    );
   }
 
   Widget _buildItem({

lib/widgets/long_list_scaffold.dart

@@ -0,0 +1,218 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/widgets.dart';
+import '../providers/settings.dart';
+import 'loading.dart';
+import 'link.dart';
+
+class LongListPayload<T, K> {
+  T header;
+  int totalCount;
+  String cursor;
+  List<K> leadingItems;
+  List<K> trailingItems;
+
+  LongListPayload({
+    this.header,
+    this.totalCount,
+    this.cursor,
+    this.leadingItems,
+    this.trailingItems,
+  });
+}
+
+// This is a scaffold for issue and pull request
+// Since the list could be very long, and some users may only want to to check trailing items
+// We should load leading and trailing items at first fetching, and do load more in the middle
+// e.g. https://github.com/reactjs/rfcs/pull/68
+class LongListScaffold<T, K> extends StatefulWidget {
+  final Widget title;
+  final List<Widget> actions;
+  final Widget trailing;
+  final Widget Function(T headerPayload) headerBuilder;
+  final Widget Function(K itemPayload) itemBuilder;
+  final Future<LongListPayload<T, K>> Function() onRefresh;
+  final Future<LongListPayload<T, K>> Function(String cursor) onLoadMore;
+
+  LongListScaffold({
+    @required this.title,
+    this.actions,
+    this.trailing,
+    @required this.headerBuilder,
+    @required this.itemBuilder,
+    @required this.onRefresh,
+    @required this.onLoadMore,
+  });
+
+  @override
+  _LongListScaffoldState createState() => _LongListScaffoldState();
+}
+
+class _LongListScaffoldState<T, K> extends State<LongListScaffold<T, K>> {
+  bool loading;
+  bool loadingMore = false;
+  LongListPayload<T, K> payload;
+
+  @override
+  void initState() {
+    super.initState();
+    _refresh();
+  }
+
+  Future<void> _refresh() async {
+    print('long list scaffold refresh');
+    setState(() {
+      loading = true;
+    });
+    try {
+      payload = await widget.onRefresh();
+    } finally {
+      if (mounted) {
+        setState(() {
+          loading = false;
+        });
+      }
+    }
+  }
+
+  Future<void> _loadMore() async {
+    print('long list scaffold load more');
+    setState(() {
+      loadingMore = true;
+    });
+    try {
+      var _payload = await widget.onLoadMore(payload.cursor);
+      payload.totalCount = _payload.totalCount;
+      payload.cursor = _payload.cursor;
+      payload.leadingItems.addAll(_payload.leadingItems);
+    } finally {
+      if (mounted) {
+        setState(() {
+          loadingMore = false;
+        });
+      }
+    }
+  }
+
+  Widget _buildItem(BuildContext context, int index) {
+    if (index % 2 == 1) {
+      return Container(
+        decoration: BoxDecoration(
+          border: Border(bottom: BorderSide(color: Colors.black12)),
+        ),
+      );
+    }
+
+    int realIndex = index ~/ 2;
+
+    if (realIndex < payload.leadingItems.length) {
+      return widget.itemBuilder(payload.leadingItems[realIndex]);
+    } else if (realIndex == payload.leadingItems.length) {
+      var count = payload.totalCount -
+          payload.leadingItems.length +
+          payload.trailingItems.length;
+      return Container(
+        padding: EdgeInsets.all(16),
+        decoration: BoxDecoration(
+          image: DecorationImage(
+            image: ExactAssetImage('images/progressive-disclosure-line.png',
+                scale: 2),
+            repeat: ImageRepeat.repeatX,
+          ),
+        ),
+        child: Center(
+          child: Link(
+            beforeRedirect: _loadMore,
+            child: Container(
+              padding: EdgeInsets.all(10),
+              decoration: BoxDecoration(
+                border: Border.all(color: Colors.black12),
+              ),
+              child: Column(
+                children: <Widget>[
+                  Text('$count hidden items',
+                      style: TextStyle(color: Colors.black87, fontSize: 15)),
+                  Padding(padding: EdgeInsets.only(top: 4)),
+                  loadingMore
+                      ? CupertinoActivityIndicator()
+                      : Text(
+                          'Load more...',
+                          style:
+                              TextStyle(color: Colors.blueAccent, fontSize: 16),
+                        ),
+                ],
+              ),
+            ),
+          ),
+        ),
+      );
+    } else {
+      return widget.itemBuilder(
+          payload.trailingItems[realIndex - payload.leadingItems.length - 1]);
+    }
+  }
+
+  int get _itemCount {
+    int count = payload.leadingItems.length + payload.trailingItems.length;
+    if (payload.totalCount > count) {
+      count++;
+    }
+    return 2 * count; // including bottom border
+  }
+
+  Widget _buildSliver() {
+    if (loading) {
+      return SliverToBoxAdapter(child: Loading(more: false));
+    } else {
+      return SliverList(
+        delegate:
+            SliverChildBuilderDelegate(_buildItem, childCount: _itemCount),
+      );
+    }
+  }
+
+  Widget _buildBody() {
+    if (loading) {
+      return Loading(more: false);
+    } else {
+      return ListView.builder(itemCount: _itemCount, itemBuilder: _buildItem);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    switch (SettingsProvider.of(context).theme) {
+      case ThemeMap.cupertino:
+        List<Widget> slivers = [
+          CupertinoSliverRefreshControl(onRefresh: widget.onRefresh)
+        ];
+        if (payload != null) {
+          slivers.add(
+            SliverToBoxAdapter(child: widget.headerBuilder(payload.header)),
+          );
+        }
+        slivers.add(_buildSliver());
+
+        return CupertinoPageScaffold(
+          navigationBar: CupertinoNavigationBar(
+            middle: widget.title,
+            trailing: widget.trailing,
+          ),
+          child: SafeArea(
+            child: CustomScrollView(slivers: slivers),
+          ),
+        );
+      default:
+        return Scaffold(
+          appBar: AppBar(
+            title: widget.title,
+            actions: widget.actions,
+          ),
+          body: RefreshIndicator(
+            onRefresh: widget.onRefresh,
+            child: _buildBody(),
+          ),
+        );
+    }
+  }
+}

lib/widgets/notification_item.dart

@@ -55,9 +55,17 @@ class _NotificationItemState extends State<NotificationItem> {
   Widget _buildRoute(BuildContext context) {
     switch (payload.type) {
       case 'Issue':
-        return IssueScreen(payload.number, payload.owner, payload.name);
+        return IssueScreen(
+          number: payload.number,
+          owner: payload.owner,
+          name: payload.name,
+        );
       case 'PullRequest':
-        return PullRequestScreen(payload.number, payload.owner, payload.name);
+        return PullRequestScreen(
+          number: payload.number,
+          owner: payload.owner,
+          name: payload.name,
+        );
       case 'Release':
       // return
       default:

lib/widgets/timeline_item.dart

@@ -7,9 +7,8 @@ import 'user_name.dart';
 
 class TimelineItem extends StatelessWidget {
   final Map<String, dynamic> item;
-  final Map<String, dynamic> payload;
 
-  TimelineItem(this.item, this.payload);
+  TimelineItem(this.item);
 
   TextSpan _buildReviewText(BuildContext context, item) {
     switch (item['state']) {
@@ -189,7 +188,9 @@ class TimelineItem extends StatelessWidget {
       case 'ReviewRequestedEvent':
         return _buildItem(
           iconData: Octicons.eye,
-          actor: payload['author']['login'],
+          // actor: payload['author']['login'],
+          // TODO:
+          actor: 'test',
           textSpan: TextSpan(children: [
             TextSpan(text: ' requested a review from '),
             createUserSpan(item['requestedReviewer']['login']),
@@ -247,10 +248,6 @@ class TimelineItem extends StatelessWidget {
   Widget build(BuildContext context) {
     return Container(
       padding: EdgeInsets.all(10),
-      decoration: BoxDecoration(
-          border: Border(
-              bottom:
-                  BorderSide(color: CupertinoColors.extraLightBackgroundGray))),
       child: _buildByType(context),
     );
   }

pubspec.yaml

@@ -21,7 +21,10 @@ dependencies:
   github: ^4.1.0
   intl: ^0.15.7
   url_launcher: ^4.2.0
+  uni_links: ^0.1.4
   flutter_markdown: ^0.2.0
+  shared_preferences: ^0.5.0
+  nanoid: ^0.0.6
 
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.
@@ -48,6 +51,9 @@ flutter:
   #  - images/a_dot_burr.jpeg
   #  - images/a_dot_ham.jpeg
 
+  assets:
+    - images/
+
   # An image asset can refer to one or more resolution-specific "variants", see
   # https://flutter.io/assets-and-images/#resolution-aware.