import 'package:flutter/material.dart';

import '../../../../app/di/injection.dart';
import '../../../../core/auth/session_store.dart';
import '../../../../core/logging/logger.dart';
import '../../../../data/network/api_client.dart';
import '../../../../data/storage/local_kv_store.dart';
import '../../../../l10n/app_localizations.dart';
import '../../../../shared/theme/app_color_palette.dart';
import '../../../../shared/theme/design_tokens.dart';
import '../../../../shared/utils/time_format.dart';
import '../../../../shared/widgets/app_loading_indicator.dart';
import '../../data/apis/points_api.dart';
import '../../data/models/ledger_item.dart';

class PointsLedgerScreen extends StatefulWidget {
  const PointsLedgerScreen({super.key});

  @override
  State<PointsLedgerScreen> createState() => _PointsLedgerScreenState();
}

class _PointsLedgerScreenState extends State<PointsLedgerScreen> {
  final Logger _logger = getLogger('features.points.ledger_screen');
  late final ScrollController _scrollController;
  late final PointsApi _api;
  final List<LedgerItem> _items = [];
  String? _nextCursor;
  bool _hasMore = false;
  bool _isLoading = false;
  bool _isLoadingMore = false;
  Object? _error;

  @override
  void initState() {
    super.initState();
    _scrollController = ScrollController()..addListener(_onScroll);
    final sessionStore = SessionStore(LocalKvStore());
    final apiClient = ApiClient(
      baseUrl: appDependencies.backendUrl,
      tokenProvider: sessionStore.getToken,
    );
    _api = PointsApi(apiClient.rawDio);
    _loadInitial();
  }

  @override
  void dispose() {
    _scrollController.removeListener(_onScroll);
    _scrollController.dispose();
    super.dispose();
  }

  void _onScroll() {
    if (!_scrollController.hasClients) return;
    final position = _scrollController.position;
    if (position.pixels >= position.maxScrollExtent - 240) {
      _loadMore();
    }
  }

  Future<void> _loadInitial() async {
    if (_isLoading) return;
    setState(() {
      _isLoading = true;
      _error = null;
    });

    try {
      final result = await _api.getLedger();

      if (mounted) {
        setState(() {
          _items.clear();
          _items.addAll(result.items);
          _nextCursor = result.nextCursor;
          _hasMore = result.hasMore;
          _isLoading = false;
        });
      }
    } catch (e, stackTrace) {
      _logger.error(
        message: 'Failed to load ledger',
        error: e,
        stackTrace: stackTrace,
      );
      if (mounted) {
        setState(() {
          _error = e;
          _isLoading = false;
        });
      }
    }
  }

  Future<void> _loadMore() async {
    if (_isLoadingMore || !_hasMore || _nextCursor == null) return;

    setState(() {
      _isLoadingMore = true;
    });

    try {
      final result = await _api.getLedger(cursor: _nextCursor);

      if (mounted) {
        setState(() {
          _items.addAll(result.items);
          _nextCursor = result.nextCursor;
          _hasMore = result.hasMore;
          _isLoadingMore = false;
        });
      }
    } catch (e, stackTrace) {
      _logger.error(
        message: 'Failed to load more ledger items',
        error: e,
        stackTrace: stackTrace,
      );
      if (mounted) {
        setState(() {
          _isLoadingMore = false;
        });
      }
    }
  }

  String _getDisplayText(AppLocalizations l10n, String changeType) {
    return switch (changeType) {
      'register' => l10n.pointsLedgerTypeRegister,
      'purchase' => l10n.pointsLedgerTypePurchase,
      'consume' => l10n.pointsLedgerTypeConsume,
      'adjust' => l10n.pointsLedgerTypeAdjust,
      'refund' => l10n.pointsLedgerTypeRefund,
      _ => changeType,
    };
  }

  IconData _getIcon(String changeType) {
    return switch (changeType) {
      'register' => Icons.card_giftcard_rounded,
      'purchase' => Icons.shopping_bag_rounded,
      'consume' => Icons.chat_bubble_outline_rounded,
      'adjust' => Icons.tune_rounded,
      'refund' => Icons.replay_rounded,
      _ => Icons.swap_vert_rounded,
    };
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final colors = Theme.of(context).colorScheme;
    final palette = Theme.of(context).extension<AppColorPalette>()!;

    return Scaffold(
      backgroundColor: colors.surfaceContainerLow,
      appBar: AppBar(
        title: Text(l10n.pointsLedgerTitle),
        centerTitle: true,
        backgroundColor: colors.surfaceContainerLow,
        surfaceTintColor: colors.surfaceContainerLow,
      ),
      body: _buildBody(l10n, colors, palette),
    );
  }

  Widget _buildBody(
    AppLocalizations l10n,
    ColorScheme colors,
    AppColorPalette palette,
  ) {
    if (_isLoading) {
      return const Center(child: AppLoadingIndicator());
    }

    if (_error != null && _items.isEmpty) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(Icons.error_outline, size: 48, color: colors.error),
            const SizedBox(height: AppSpacing.md),
            Text(
              l10n.errorRequestGeneric,
              style: Theme.of(context).textTheme.bodyMedium,
            ),
            const SizedBox(height: AppSpacing.lg),
            FilledButton(onPressed: _loadInitial, child: Text(l10n.retry)),
          ],
        ),
      );
    }

    if (_items.isEmpty) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(
              Icons.receipt_long_outlined,
              size: 64,
              color: colors.onSurfaceVariant.withValues(alpha: 0.5),
            ),
            const SizedBox(height: AppSpacing.md),
            Text(
              l10n.pointsLedgerEmpty,
              style: Theme.of(
                context,
              ).textTheme.bodyMedium?.copyWith(color: colors.onSurfaceVariant),
            ),
          ],
        ),
      );
    }

    return ListView.builder(
      controller: _scrollController,
      padding: const EdgeInsets.all(AppSpacing.lg),
      itemCount: _items.length + (_hasMore ? 1 : 0),
      itemBuilder: (context, index) {
        if (index == _items.length) {
          if (_isLoadingMore) {
            return const Padding(
              padding: EdgeInsets.all(AppSpacing.lg),
              child: Center(child: AppLoadingIndicator()),
            );
          }
          return const SizedBox.shrink();
        }

        final item = _items[index];
        final isIncome = item.direction == 1;
        final amountText = isIncome ? '+${item.amount}' : '-${item.amount}';

        return _LedgerItemCard(
          icon: _getIcon(item.changeType),
          displayText: _getDisplayText(l10n, item.changeType),
          amountText: amountText,
          isIncome: isIncome,
          balanceAfter: item.balanceAfter,
          balanceText: l10n.pointsLedgerBalance(item.balanceAfter),
          dateTime: formatCompactLocalDateTime(item.createdAt),
          colors: colors,
          palette: palette,
        );
      },
    );
  }
}

class _LedgerItemCard extends StatelessWidget {
  const _LedgerItemCard({
    required this.icon,
    required this.displayText,
    required this.amountText,
    required this.isIncome,
    required this.balanceAfter,
    required this.balanceText,
    required this.dateTime,
    required this.colors,
    required this.palette,
  });

  final IconData icon;
  final String displayText;
  final String amountText;
  final bool isIncome;
  final int balanceAfter;
  final String balanceText;
  final String dateTime;
  final ColorScheme colors;
  final AppColorPalette palette;

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: const EdgeInsets.only(bottom: AppSpacing.sm),
      padding: const EdgeInsets.all(AppSpacing.md),
      decoration: BoxDecoration(
        color: colors.surface,
        borderRadius: BorderRadius.circular(AppRadius.lg),
        border: Border.all(color: colors.outlineVariant),
      ),
      child: Row(
        children: [
          Container(
            width: 40,
            height: 40,
            decoration: BoxDecoration(
              color: isIncome
                  ? palette.incomeGreenBg.withValues(alpha: 0.15)
                  : colors.errorContainer.withValues(alpha: 0.5),
              borderRadius: BorderRadius.circular(AppRadius.md),
            ),
            child: Icon(
              icon,
              size: 22,
              color: isIncome ? palette.incomeGreenText : colors.error,
            ),
          ),
          const SizedBox(width: AppSpacing.md),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  displayText,
                  style: Theme.of(
                    context,
                  ).textTheme.bodyMedium?.copyWith(fontWeight: FontWeight.w600),
                ),
                const SizedBox(height: 2),
                Text(
                  dateTime,
                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
                    color: colors.onSurfaceVariant,
                  ),
                ),
              ],
            ),
          ),
          Column(
            crossAxisAlignment: CrossAxisAlignment.end,
            children: [
              Text(
                amountText,
                style: Theme.of(context).textTheme.titleMedium?.copyWith(
                  fontWeight: FontWeight.w700,
                  color: isIncome ? palette.incomeGreenText : colors.error,
                ),
              ),
              const SizedBox(height: 2),
              Text(
                balanceText,
                style: Theme.of(
                  context,
                ).textTheme.bodySmall?.copyWith(color: colors.onSurfaceVariant),
              ),
            ],
          ),
        ],
      ),
    );
  }
}