feat: add variant support to board editor

lib/src/model/board_editor/board_editor_controller.dart

@@ -3,26 +3,34 @@ import 'package:dartchess/dartchess.dart';
 import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:freezed_annotation/freezed_annotation.dart';
+import 'package:lichess_mobile/src/model/common/chess.dart';
+import 'package:lichess_mobile/src/model/common/chess960.dart';
 
 part 'board_editor_controller.freezed.dart';
 
+typedef BoardEditorControllerParams = ({Variant initialVariant, String? initialFen});
+
 /// A provider for [BoardEditorController].
 final boardEditorControllerProvider = NotifierProvider.autoDispose
-    .family<BoardEditorController, BoardEditorState, String?>(
+    .family<BoardEditorController, BoardEditorState, BoardEditorControllerParams?>(
       BoardEditorController.new,
       name: 'BoardEditorControllerProvider',
     );
 
 class BoardEditorController extends Notifier<BoardEditorState> {
-  BoardEditorController(this.initialFen);
+  BoardEditorController(this.params);
 
-  final String? initialFen;
+  final BoardEditorControllerParams? params;
 
   @override
   BoardEditorState build() {
-    final setup = Setup.parseFen(initialFen ?? kInitialFEN);
-    final position = Chess.fromSetup(setup, ignoreImpossibleCheck: true);
-    final pieces = readFen(initialFen ?? kInitialFEN).lock;
+    final variant = params?.initialVariant ?? Variant.standard;
+    final fen =
+        params?.initialFen ??
+        (variant == Variant.chess960 ? randomChess960Position() : variant.initialPosition).fen;
+    final setup = Setup.parseFen(fen);
+    final position = Position.setupPosition(variant.rule, setup, ignoreImpossibleCheck: true);
+    final pieces = readFen(fen).lock;
 
     final castlingRights = IMap({
       CastlingRight.whiteKing: position.castles.rookOf(Side.white, CastlingSide.king) != null,
@@ -33,6 +41,7 @@ class BoardEditorController extends Notifier<BoardEditorState> {
     return BoardEditorState(
       orientation: Side.white,
       sideToPlay: setup.turn,
+      variant: variant,
       pieces: pieces,
       castlingRights: castlingRights,
       editorPointerMode: EditorPointerMode.drag,
@@ -131,6 +140,10 @@ class BoardEditorController extends Notifier<BoardEditorState> {
     state = state.copyWith(enPassantSquare: state.enPassantSquare == square ? null : square);
   }
 
+  void setVariant(Variant variant) {
+    state = state.copyWith(variant: variant);
+  }
+
   void _updatePosition(IMap<Square, Piece> pieces) {
     state = state.copyWith(
       pieces: pieces,
@@ -175,6 +188,7 @@ sealed class BoardEditorState with _$BoardEditorState {
   const factory BoardEditorState({
     required Side orientation,
     required Side sideToPlay,
+    required Variant variant,
     required IMap<Square, Piece> pieces,
     required IMap<CastlingRight, bool> castlingRights,
     required EditorPointerMode editorPointerMode,
@@ -261,9 +275,9 @@ sealed class BoardEditorState with _$BoardEditorState {
   /// Returns `null` if the position is invalid.
   String? get pgn {
     try {
-      final position = Chess.fromSetup(Setup.parseFen(fen));
+      final position = Position.setupPosition(variant.rule, Setup.parseFen(fen));
       return PgnGame(
-        headers: {'FEN': position.fen},
+        headers: {'FEN': position.fen, 'Variant': variant.label},
         moves: PgnNode<PgnNodeData>(),
         comments: [],
       ).makePgn();

lib/src/model/common/chess.dart

@@ -98,6 +98,15 @@ enum Variant {
   final String label;
   final IconData icon;
 
+  bool sideCanCastle(Side side) {
+    if (this == Variant.racingKings) return false;
+    if (this == Variant.antichess) return false;
+    if (side == Side.white && this == Variant.horde) return false;
+    return true;
+  }
+
+  bool get hasEnPassant => this != Variant.racingKings;
+
   bool get isReadSupported => readSupportedVariants.contains(this);
 
   bool get isPlaySupported => playSupportedVariants.contains(this);

lib/src/model/common/chess960.dart

@@ -4,14 +4,20 @@ import 'package:dartchess/dartchess.dart';
 
 final _random = Random.secure();
 
-Position randomChess960Position() {
-  final rank8 = _positions[_random.nextInt(_positions.length)];
+Position chess960Position(int index) {
+  if (index < 0 || index >= _positions.length) {
+    throw ArgumentError('Index must be between 0 and ${_positions.length - 1}');
+  }
+
+  final rank8 = _positions[index];
 
   return Chess.fromSetup(
     Setup.parseFen('$rank8/pppppppp/8/8/8/8/PPPPPPPP/${rank8.toUpperCase()} w KQkq - 0 1'),
   );
 }
 
+Position randomChess960Position() => chess960Position(_random.nextInt(_positions.length));
+
 // https://github.com/lichess-org/scalachess/blob/bd139c6dc1acdc8fff08c46e412f784d49a16578/core/src/main/scala/variant/Chess960.scala#L49
 final _positions = [
   'bbqnnrkr',

lib/src/view/analysis/analysis_screen.dart

@@ -41,9 +41,9 @@ import 'package:lichess_mobile/src/widgets/adaptive_choice_picker.dart';
 import 'package:lichess_mobile/src/widgets/bottom_bar.dart';
 import 'package:lichess_mobile/src/widgets/buttons.dart';
 import 'package:lichess_mobile/src/widgets/feedback.dart';
-import 'package:lichess_mobile/src/widgets/misc.dart';
 import 'package:lichess_mobile/src/widgets/platform_context_menu_button.dart';
 import 'package:lichess_mobile/src/widgets/user.dart';
+import 'package:lichess_mobile/src/widgets/variant_app_bar_title.dart';
 import 'package:logging/logging.dart';
 import 'package:share_plus/share_plus.dart';
 import 'package:url_launcher/url_launcher.dart';
@@ -193,7 +193,7 @@ class _AnalysisScreenState extends ConsumerState<_AnalysisScreen>
             resizeToAvoidBottomInset: false,
             appBar: AppBar(
               centerTitle: false,
-              title: _Title(variant: value.variant),
+              title: VariantAppBarTitle(variant: value.variant, title: context.l10n.analysis),
               actions: appBarActions,
             ),
             body: _Body(options: widget.options, controller: _tabController),
@@ -207,7 +207,7 @@ class _AnalysisScreenState extends ConsumerState<_AnalysisScreen>
           resizeToAvoidBottomInset: false,
           appBar: AppBar(
             centerTitle: false,
-            title: const _Title(variant: Variant.standard),
+            title: VariantAppBarTitle(variant: Variant.standard, title: context.l10n.analysis),
             actions: appBarActions,
           ),
           body: const Center(child: CircularProgressIndicator.adaptive()),
@@ -275,25 +275,6 @@ class _AnalysisMenu extends ConsumerWidget {
   }
 }
 
-class _Title extends StatelessWidget {
-  const _Title({required this.variant});
-
-  final Variant variant;
-
-  static const excludedIcons = [Variant.standard, Variant.fromPosition];
-
-  @override
-  Widget build(BuildContext context) {
-    return Row(
-      mainAxisSize: MainAxisSize.min,
-      children: [
-        if (!excludedIcons.contains(variant)) ...[Icon(variant.icon), const SizedBox(width: 5.0)],
-        Flexible(child: AppBarTitleText(context.l10n.analysis)),
-      ],
-    );
-  }
-}
-
 class _Body extends ConsumerWidget {
   const _Body({required this.options, required this.controller});
 
@@ -677,9 +658,12 @@ class _BottomBar extends ConsumerWidget {
             makeLabel: (context) => Text(context.l10n.boardEditor),
             onPressed: () {
               final boardFen = analysisState.currentPosition.fen;
-              Navigator.of(
-                context,
-              ).push(BoardEditorScreen.buildRoute(context, initialFen: boardFen));
+              Navigator.of(context).push(
+                BoardEditorScreen.buildRoute(context, (
+                  initialVariant: analysisState.variant,
+                  initialFen: boardFen,
+                )),
+              );
             },
           ),
         if (analysisState.isComputerAnalysisAllowed)

lib/src/view/board_editor/board_editor_filters.dart

@@ -1,4 +1,5 @@
 import 'package:dartchess/dartchess.dart' hide Position;
+import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:lichess_mobile/src/model/board_editor/board_editor_controller.dart';
@@ -7,15 +8,19 @@ import 'package:lichess_mobile/src/utils/l10n_context.dart';
 import 'package:lichess_mobile/src/widgets/adaptive_bottom_sheet.dart';
 
 class BoardEditorFilters extends ConsumerWidget {
-  const BoardEditorFilters({required this.initialFen, super.key});
+  const BoardEditorFilters({required this.params, super.key});
 
-  final String? initialFen;
+  final BoardEditorControllerParams? params;
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    final editorController = boardEditorControllerProvider(initialFen);
+    final editorController = boardEditorControllerProvider(params);
     final editorState = ref.watch(editorController);
 
+    final castlingSide = Side.values
+        .where((side) => editorState.variant.sideCanCastle(side))
+        .toIList();
+
     return BottomSheetScrollableContainer(
       padding: const EdgeInsets.symmetric(vertical: 16.0, horizontal: 8.0),
       children: [
@@ -36,53 +41,60 @@ class BoardEditorFilters extends ConsumerWidget {
             }).toList(),
           ),
         ),
-        Padding(
-          padding: Styles.bodySectionPadding,
-          child: Text(context.l10n.castling, style: Styles.title),
-        ),
-        ...Side.values.map((side) {
-          return Padding(
-            padding: Styles.horizontalBodyPadding,
-            child: Row(
-              spacing: 8.0,
-              children: [
-                SizedBox(
-                  width: 100.0,
-                  child: Text(
-                    side == Side.white ? context.l10n.white : context.l10n.black,
-                    maxLines: 1,
-                    overflow: TextOverflow.ellipsis,
+        if (castlingSide.isNotEmpty) ...[
+          Padding(
+            padding: Styles.bodySectionPadding,
+            child: Text(context.l10n.castling, style: Styles.title),
+          ),
+          ...Side.values.where((side) => editorState.variant.sideCanCastle(side)).map((side) {
+            return Padding(
+              padding: Styles.horizontalBodyPadding,
+              child: Row(
+                spacing: 8.0,
+                children: [
+                  SizedBox(
+                    width: 100.0,
+                    child: Text(
+                      side == Side.white ? context.l10n.white : context.l10n.black,
+                      maxLines: 1,
+                      overflow: TextOverflow.ellipsis,
+                    ),
                   ),
-                ),
-                ...[CastlingSide.king, CastlingSide.queen].map((castlingSide) {
-                  return ChoiceChip(
-                    label: Text(castlingSide == CastlingSide.king ? 'O-O' : 'O-O-O'),
-                    selected: editorState.isCastlingAllowed(side, castlingSide),
-                    onSelected: (selected) {
-                      ref.read(editorController.notifier).setCastling(side, castlingSide, selected);
-                    },
-                  );
-                }),
-              ],
-            ),
-          );
-        }),
-        if (editorState.enPassantOptions.isNotEmpty) ...[
+                  ...[CastlingSide.king, CastlingSide.queen].map((castlingSide) {
+                    return ChoiceChip(
+                      label: Text(castlingSide == CastlingSide.king ? 'O-O' : 'O-O-O'),
+                      selected: editorState.isCastlingAllowed(side, castlingSide),
+                      onSelected: (selected) {
+                        ref
+                            .read(editorController.notifier)
+                            .setCastling(side, castlingSide, selected);
+                      },
+                    );
+                  }),
+                ],
+              ),
+            );
+          }),
+        ],
+        if (editorState.variant.hasEnPassant && editorState.enPassantOptions.isNotEmpty) ...[
           const Padding(
             padding: Styles.bodySectionPadding,
             child: Text('En passant', style: Styles.subtitle),
           ),
-          Wrap(
-            spacing: 8.0,
-            children: editorState.enPassantOptions.squares.map((square) {
-              return ChoiceChip(
-                label: Text(square.name),
-                selected: editorState.enPassantSquare == square,
-                onSelected: (selected) {
-                  ref.read(editorController.notifier).toggleEnPassantSquare(square);
-                },
-              );
-            }).toList(),
+          Padding(
+            padding: Styles.horizontalBodyPadding,
+            child: Wrap(
+              spacing: 8.0,
+              children: editorState.enPassantOptions.squares.map((square) {
+                return ChoiceChip(
+                  label: Text(square.name),
+                  selected: editorState.enPassantSquare == square,
+                  onSelected: (selected) {
+                    ref.read(editorController.notifier).toggleEnPassantSquare(square);
+                  },
+                );
+              }).toList(),
+            ),
           ),
         ],
       ],