import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../game/engine/game_engine.dart';
import '../../l10n/gen/app_localizations.dart';
import '../../services/audio_service.dart';
import '../../state/game_session_notifier.dart';
import '../../state/providers.dart';
import '../theme/palette.dart';
import '../widgets/board_geometry.dart';
import '../widgets/board_painter.dart';
import '../widgets/board_widget.dart';
import '../widgets/hud_widget.dart';
import '../widgets/piece_painter.dart';
import '../widgets/tray_widget.dart';

/// Renders whatever session [gameSessionProvider] holds; callers start the
/// stage (via SeasonFlowNotifier) before navigating here.
class GameScreen extends ConsumerStatefulWidget {
  const GameScreen({super.key});

  @override
  ConsumerState<GameScreen> createState() => _GameScreenState();
}

class _GameScreenState extends ConsumerState<GameScreen> {
  final _boardKey = GlobalKey();
  final _stackKey = GlobalKey();

  int? _dragIndex;
  Offset? _dragGlobal;

  /// How far the dragged piece floats above the finger so it stays visible.
  static const double _lift = 70;

  RenderBox? get _boardBox =>
      _boardKey.currentContext?.findRenderObject() as RenderBox?;

  /// Global top-left of the dragged piece, rendered at board cell size.
  Offset? _draggedPieceTopLeft(GameViewState view) {
    final i = _dragIndex;
    final g = _dragGlobal;
    final box = _boardBox;
    if (i == null || g == null || box == null || i >= view.tray.length) {
      return null;
    }
    final geo = BoardGeometry(boardSize: box.size.width);
    final piece = view.tray[i];
    final (w, h) = pieceCellBounds(piece);
    final pw = w * geo.cellSize;
    final ph = h * geo.cellSize;
    return g + Offset(-pw / 2, -_lift - ph);
  }

  GhostSpec? _ghost(GameViewState view) {
    final i = _dragIndex;
    final box = _boardBox;
    final topLeftGlobal = _draggedPieceTopLeft(view);
    if (i == null || box == null || topLeftGlobal == null) return null;

    final geo = BoardGeometry(boardSize: box.size.width);
    final piece = view.tray[i];
    final (w, h) = pieceCellBounds(piece);
    final centerLocal = box.globalToLocal(
      topLeftGlobal + Offset(w * geo.cellSize / 2, h * geo.cellSize / 2),
    );
    // Only preview while the piece is actually over the board.
    if (centerLocal.dx < -geo.cellSize ||
        centerLocal.dy < -geo.cellSize ||
        centerLocal.dx > box.size.width + geo.cellSize ||
        centerLocal.dy > box.size.height + geo.cellSize) {
      return null;
    }

    final topLeftLocal = box.globalToLocal(topLeftGlobal);
    final (ax, ay) = geo.snapAnchor(piece, topLeftLocal);
    final legal =
        ref.read(gameSessionProvider.notifier).canPlaceAt(i, ax, ay);
    return GhostSpec(piece: piece, anchorX: ax, anchorY: ay, legal: legal);
  }

  void _onDragEnd(GameViewState view) {
    final i = _dragIndex;
    final ghost = _ghost(view);
    setState(() {
      _dragIndex = null;
      _dragGlobal = null;
    });
    if (i != null && ghost != null && ghost.legal) {
      ref
          .read(gameSessionProvider.notifier)
          .tryPlace(i, ghost.anchorX, ghost.anchorY);
    }
  }

  void _onSessionChange(GameViewState? prev, GameViewState? next) {
    if (next == null) return;
    final audio = ref.read(audioServiceProvider);
    if (prev?.fxTick != next.fxTick && next.lastPlacement != null) {
      final placement = next.lastPlacement!;
      if (placement.linesCleared > 0) {
        audio.play(placement.comboStreak >= 2 ? Sfx.combo : Sfx.clear);
      } else {
        audio.play(Sfx.place);
      }
    }
    if (prev?.phase != next.phase) {
      if (next.phase == GamePhase.won) {
        audio.play(Sfx.win);
        // recordResult keeps the best run, so re-entry is harmless.
        ref
            .read(seasonFlowProvider.notifier)
            .recordWin(stars: next.starsEarned, score: next.score);
      }
      if (next.phase == GamePhase.lost) audio.play(Sfx.lose);
    }
  }

  @override
  Widget build(BuildContext context) {
    ref.listen<GameViewState?>(gameSessionProvider, _onSessionChange);
    final view = ref.watch(gameSessionProvider);
    if (view == null) {
      return const Scaffold(body: Center(child: CircularProgressIndicator()));
    }

    final ghost = _ghost(view);
    final draggedTopLeft = _draggedPieceTopLeft(view);
    final boardBox = _boardBox;

    return Scaffold(
      body: SafeArea(
        child: Stack(
          key: _stackKey,
          children: [
            Padding(
              padding: const EdgeInsets.all(16),
              child: Column(
                children: [
                  HudWidget(view: view),
                  Expanded(
                    child: Center(
                      child: BoardWidget(
                        key: _boardKey,
                        view: view,
                        ghost: ghost,
                      ),
                    ),
                  ),
                  TrayWidget(
                    tray: view.tray,
                    draggingIndex: _dragIndex,
                    onDragStart: (index, global) => setState(() {
                      _dragIndex = index;
                      _dragGlobal = global;
                    }),
                    onDragUpdate: (global) =>
                        setState(() => _dragGlobal = global),
                    onDragEnd: () => _onDragEnd(view),
                  ),
                ],
              ),
            ),
            if (_dragIndex != null &&
                draggedTopLeft != null &&
                boardBox != null &&
                _dragIndex! < view.tray.length)
              _draggedPieceOverlay(view, draggedTopLeft, boardBox),
            if (view.phase != GamePhase.playing) _resultOverlay(view),
            if (Navigator.of(context).canPop())
              Positioned(
                top: 4,
                left: 4,
                child: IconButton(
                  icon: const Icon(Icons.close, color: Colors.white54),
                  onPressed: () => Navigator.of(context).pop(),
                ),
              ),
          ],
        ),
      ),
    );
  }

  Widget _draggedPieceOverlay(
      GameViewState view, Offset topLeftGlobal, RenderBox boardBox) {
    final stackBox =
        _stackKey.currentContext!.findRenderObject()! as RenderBox;
    final local = stackBox.globalToLocal(topLeftGlobal);
    final cellSize = boardBox.size.width / 8;
    return Positioned(
      left: local.dx,
      top: local.dy,
      child: IgnorePointer(
        child: PieceWidget(piece: view.tray[_dragIndex!], cellSize: cellSize),
      ),
    );
  }

  Widget _resultOverlay(GameViewState view) {
    final l10n = AppLocalizations.of(context)!;
    final notifier = ref.read(gameSessionProvider.notifier);
    final theme = Theme.of(context);

    final flow = ref.read(seasonFlowProvider);
    final (title, actions) = switch ((view.phase, view.stuckReason)) {
      (GamePhase.won, _) => (
          l10n.stageClear,
          [
            if (flow != null && flow.hasNext)
              FilledButton(
                onPressed:
                    ref.read(seasonFlowProvider.notifier).nextStage,
                child: Text(l10n.nextStage),
              ),
            TextButton(
              onPressed: notifier.restart,
              child: Text(l10n.playAgain),
            ),
          ],
        ),
      (GamePhase.stuck, StuckReason.outOfMoves) => (
          l10n.outOfMoves,
          [
            FilledButton(
              onPressed: notifier.addExtraMoves,
              child: Text(l10n.plusFiveMoves),
            ),
            TextButton(
              onPressed: notifier.declineAndLose,
              child: Text(l10n.giveUp),
            ),
          ],
        ),
      (GamePhase.stuck, _) => (
          l10n.boardFull,
          [
            FilledButton(
              onPressed: notifier.useContinue,
              child: Text(l10n.watchAdContinue),
            ),
            TextButton(
              onPressed: notifier.declineAndLose,
              child: Text(l10n.giveUp),
            ),
          ],
        ),
      (_, _) => (
          l10n.stageFailed,
          [
            FilledButton(
              onPressed: notifier.restart,
              child: Text(l10n.playAgain),
            ),
          ],
        ),
    };

    return Positioned.fill(
      child: ColoredBox(
        color: Colors.black54,
        child: Center(
          child: Card(
            color: GamePalette.boardBackground,
            child: Padding(
              padding: const EdgeInsets.all(24),
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Text(title, style: theme.textTheme.headlineSmall),
                  if (view.phase == GamePhase.won) ...[
                    const SizedBox(height: 12),
                    Row(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        for (var i = 0; i < 3; i++)
                          Icon(
                            Icons.star,
                            size: 40,
                            color: i < view.starsEarned
                                ? Colors.amber
                                : Colors.white24,
                          ),
                      ],
                    ),
                  ],
                  const SizedBox(height: 20),
                  ...actions,
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}