✨ improve structure.

lib/internal/delegate.dart

@@ -1,16 +1,12 @@
 import 'dart:math' as math;
 
-import 'package:flutter/material.dart';
+import 'package:extended_list_library/extended_list_library.dart'
+    show ViewportBuilder;
+import 'package:flutter/material.dart' hide ViewportBuilder;
 import 'package:flutter/rendering.dart';
+import 'package:waterfall_flow/waterfall_flow.dart';
 
 class SliverGridDelegateWithMinCrossAxisExtent extends SliverGridDelegate {
-  /// Creates a delegate that makes grid layouts with tiles that have a maximum
-  /// cross-axis extent.
-  ///
-  /// All of the arguments except [mainAxisExtent] must not be null.
-  /// The [minCrossAxisExtent], [mainAxisExtent], [mainAxisSpacing],
-  /// and [crossAxisSpacing] arguments must not be negative.
-  /// The [childAspectRatio] argument must be greater than zero.
   const SliverGridDelegateWithMinCrossAxisExtent({
     required this.minCrossAxisExtent,
     this.mainAxisSpacing = 0.0,
@@ -21,33 +17,10 @@ class SliverGridDelegateWithMinCrossAxisExtent extends SliverGridDelegate {
         assert(mainAxisSpacing >= 0),
         assert(crossAxisSpacing >= 0),
         assert(childAspectRatio > 0);
-
-  /// The maximum extent of tiles in the cross axis.
-  ///
-  /// This delegate will select a cross-axis extent for the tiles that is as
-  /// large as possible subject to the following conditions:
-  ///
-  ///  - The extent evenly divides the cross-axis extent of the grid.
-  ///  - The extent is at least [minCrossAxisExtent].
-  ///
-  /// For example, if the grid is vertical, the grid is 600.0 pixels wide, and
-  /// [minCrossAxisExtent] is 190.0, this delegate will create a grid with 3
-  /// columns that are 200.0 pixels wide.
   final double minCrossAxisExtent;
-
-  /// The number of logical pixels between each child along the main axis.
   final double mainAxisSpacing;
-
-  /// The number of logical pixels between each child along the cross axis.
   final double crossAxisSpacing;
-
-  /// The ratio of the cross-axis to the main-axis extent of each child.
   final double childAspectRatio;
-
-  /// The extent of each tile in the main axis. If provided it would define the
-  /// logical pixels taken by each tile in the main-axis.
-  ///
-  /// If null, [childAspectRatio] is used instead.
   final double? mainAxisExtent;
 
   bool _debugAssertIsValid(double crossAxisExtent) {
@@ -92,3 +65,45 @@ class SliverGridDelegateWithMinCrossAxisExtent extends SliverGridDelegate {
         oldDelegate.mainAxisExtent != mainAxisExtent;
   }
 }
+
+class SliverWaterfallFlowDelegateWithMinCrossAxisExtent
+    extends SliverWaterfallFlowDelegate {
+  const SliverWaterfallFlowDelegateWithMinCrossAxisExtent({
+    required this.minCrossAxisExtent,
+    double mainAxisSpacing = 0.0,
+    double crossAxisSpacing = 0.0,
+    LastChildLayoutTypeBuilder? lastChildLayoutTypeBuilder,
+    CollectGarbage? collectGarbage,
+    ViewportBuilder? viewportBuilder,
+    bool closeToTrailing = false,
+  })  : assert(minCrossAxisExtent >= 0),
+        super(
+          mainAxisSpacing: mainAxisSpacing,
+          crossAxisSpacing: crossAxisSpacing,
+          lastChildLayoutTypeBuilder: lastChildLayoutTypeBuilder,
+          collectGarbage: collectGarbage,
+          viewportBuilder: viewportBuilder,
+          closeToTrailing: closeToTrailing,
+        );
+
+  final double minCrossAxisExtent;
+
+  @override
+  int getCrossAxisCount(SliverConstraints constraints) {
+    final count =
+        (constraints.crossAxisExtent / (minCrossAxisExtent + crossAxisSpacing))
+            .floor();
+    return count == 0 ? 1 : count;
+  }
+
+  @override
+  bool shouldRelayout(SliverWaterfallFlowDelegate oldDelegate) {
+    if (oldDelegate.runtimeType != runtimeType) {
+      return true;
+    }
+
+    return oldDelegate is SliverWaterfallFlowDelegateWithMaxCrossAxisExtent &&
+        (oldDelegate.maxCrossAxisExtent != minCrossAxisExtent ||
+            super.shouldRelayout(oldDelegate));
+  }
+}

lib/internal/resolver.dart

@@ -533,7 +533,7 @@ class Resolver {
     if (_intro.isNotBlank) {
       _intro = "\u3000\u3000" + _intro!.replaceAll("\n", "\n\u3000\u3000");
     }
-    detail.intro = _intro;
+    detail.intro = _intro ?? "";
     detail.subscribed = document
             .querySelector(".subscribed-badge")
             ?.attributes["style"]
@@ -551,7 +551,7 @@ class Resolver {
     final List<Element> tables = document
         .querySelectorAll("#sk-container > div.central-container > table");
     final List<Element> subs = document.querySelectorAll(".subgroup-text");
-    detail.subgroupBangumis = [];
+    detail.subgroupBangumis = {};
     SubgroupBangumi subgroupBangumi;
     Element? element;
     List<Element> elements;
@@ -641,7 +641,7 @@ class Resolver {
           records.add(record);
         }
         subgroupBangumi.records = records;
-        detail.subgroupBangumis.add(subgroupBangumi);
+        detail.subgroupBangumis[subgroupBangumi.dataId] = subgroupBangumi;
       }
     }
     return detail;

lib/main.dart

@@ -104,7 +104,7 @@ class MikanApp extends StatelessWidget {
         ],
         child: Consumer<ThemeModel>(
           builder: (context, themeModel, child) {
-            final FirebaseModel firebaseModel = Provider.of<FirebaseModel>(
+            final firebaseModel = Provider.of<FirebaseModel>(
               context,
               listen: false,
             );

lib/model/bangumi_details.dart

@@ -6,8 +6,8 @@ class BangumiDetail {
   late String name;
   late bool subscribed;
   late Map<String, String> more;
-  String? intro;
-  late List<SubgroupBangumi> subgroupBangumis;
+  late String intro;
+  late Map<String, SubgroupBangumi> subgroupBangumis;
 
   @override
   bool operator ==(Object other) =>

lib/providers/bangumi_model.dart

@@ -6,7 +6,6 @@ import 'package:mikan_flutter/internal/extension.dart';
 import 'package:mikan_flutter/internal/http.dart';
 import 'package:mikan_flutter/internal/repo.dart';
 import 'package:mikan_flutter/model/bangumi_details.dart';
-import 'package:mikan_flutter/model/subgroup_bangumi.dart';
 import 'package:mikan_flutter/providers/base_model.dart';
 import 'package:palette_generator/palette_generator.dart';
 import 'package:pull_to_refresh/pull_to_refresh.dart';
@@ -46,23 +45,6 @@ class BangumiModel extends CancelableBaseModel {
         .whenComplete(() => this._loadCoverMainColor());
   }
 
-  SubgroupBangumi? _subgroupBangumi;
-
-  SubgroupBangumi? get subgroupBangumi => _subgroupBangumi;
-
-  set selectedSubgroupId(String value) {
-    if (value == _subgroupBangumi?.dataId) {
-      return;
-    }
-    _subgroupBangumi = _bangumiDetail?.subgroupBangumis
-        .firstWhere((element) => element.dataId == value);
-    _hasScrolled = false;
-    if (_refreshController.headerStatus != RefreshStatus.completed) {
-      _refreshController.loadComplete();
-    }
-    notifyListeners();
-  }
-
   Color? _coverMainColor;
 
   Color? get coverMainColor => _coverMainColor;
@@ -85,23 +67,24 @@ class BangumiModel extends CancelableBaseModel {
     });
   }
 
-  loadSubgroupList() async {
-    if ((this._subgroupBangumi?.records.length ?? 0) < 10) {
+  loadSubgroupList(final String dataId) async {
+    final sb = _bangumiDetail?.subgroupBangumis[dataId];
+    if ((sb?.records.length ?? 0) < 10) {
       return _refreshController.loadNoData();
     }
     final Resp resp = await (this +
         Repo.bangumiMore(
           this.id,
-          this._subgroupBangumi?.dataId ?? "",
-          this._subgroupBangumi?.records.length ?? 0 + 20,
+          sb?.dataId ?? "",
+          sb?.records.length ?? 0 + 20,
         ));
     if (resp.success) {
-      if (this._subgroupBangumi?.records.length == resp.data.length) {
+      if (sb?.records.length == resp.data.length) {
         _refreshController.loadNoData();
       } else {
         _refreshController.loadComplete();
       }
-      this._subgroupBangumi?.records = resp.data;
+      sb?.records = resp.data;
       notifyListeners();
     } else {
       _refreshController.loadFailed();

lib/topvars.dart

@@ -9,17 +9,21 @@ const edgeH16T4 = const EdgeInsets.only(left: 16.0, right: 16.0, top: 4.0);
 const edgeH16T8 = const EdgeInsets.only(left: 16.0, right: 16.0, top: 8.0);
 const edgeHB16T8 =
     const EdgeInsets.only(left: 16.0, right: 16.0, bottom: 16.0, top: 8.0);
+const edgeHB24 = const EdgeInsets.only(left: 24.0, right: 24.0, bottom: 24.0);
 const edgeH16T24B8 =
     const EdgeInsets.only(left: 16.0, right: 16.0, bottom: 8.0, top: 24.0);
 const edge16 = const EdgeInsets.all(16.0);
 const edge8 = const EdgeInsets.all(8.0);
 const edge10 = const EdgeInsets.all(10.0);
+const edge12 = const EdgeInsets.all(12.0);
 const edge4 = const EdgeInsets.all(4.0);
 const edgeV4 = const EdgeInsets.symmetric(vertical: 4.0);
+const edgeV8 = const EdgeInsets.symmetric(vertical: 8.0);
 const edge24 = const EdgeInsets.all(24.0);
 const edge28 = const EdgeInsets.all(28.0);
 const edgeH12V8 = const EdgeInsets.symmetric(horizontal: 12.0, vertical: 8.0);
 const edgeH16 = const EdgeInsets.symmetric(horizontal: 16.0);
+const edgeH24 = const EdgeInsets.symmetric(horizontal: 24.0);
 const edgeH8 = const EdgeInsets.symmetric(horizontal: 8.0);
 const edgeH16V12 = const EdgeInsets.symmetric(horizontal: 16.0, vertical: 12.0);
 const edgeH8V6 = const EdgeInsets.symmetric(horizontal: 8.0, vertical: 6.0);
@@ -132,7 +136,10 @@ const textStyle13 = const TextStyle(
   fontSize: 13.0,
   height: 1.25,
 );
-
+const textStyle12 = const TextStyle(
+  fontSize: 12.0,
+  height: 1.25,
+);
 const textStyle13B500 = const TextStyle(
   fontSize: 13.0,
   height: 1.25,
@@ -163,6 +170,7 @@ const sizedBoxW16 = const SizedBox(width: 16.0);
 const sizedBoxH16 = const SizedBox(height: 16.0);
 const sizedBoxW12 = const SizedBox(width: 12.0);
 const sizedBoxH12 = const SizedBox(height: 12.0);
+const sizedBoxH24 = const SizedBox(height: 24.0);
 const sizedBoxH10 = const SizedBox(height: 10.0);
 const sizedBoxH8 = const SizedBox(height: 8.0);
 const sizedBoxW8 = const SizedBox(width: 8.0);
@@ -171,12 +179,16 @@ const sizedBoxH4 = const SizedBox(height: 4.0);
 const sizedBoxH56 = const SizedBox(height: 56.0);
 const sizedBoxH42 = const SizedBox(height: 42.0);
 
+const sliverSizedBoxH64 = const SliverToBoxAdapter(
+  child: const SizedBox(height: 64.0),
+);
+
 const spacer = const Spacer();
 
 const dur240 = const Duration(milliseconds: 240);
 const dur3000 = const Duration(milliseconds: 3000);
 
-const sliverToBoxAdapter = const SliverToBoxAdapter();
+const emptySliverToBoxAdapter = const SliverToBoxAdapter();
 
 const circleShape = const CircleBorder();
 
@@ -207,3 +219,5 @@ final normalFormHeader = Row(
     )
   ],
 );
+
+const centerLoading = const Center(child: CupertinoActivityIndicator());