import 'package:flutter/material.dart';

import '../../core/api/api_config.dart';
import '../../core/api/services/user_api.dart';
import '../../core/auth/auth_service.dart';
import '../../core/theme/app_colors.dart';
import '../../core/theme/app_spacing.dart';
import '../../core/theme/app_typography.dart';
import '../../core/user/user_state.dart';
import '../../shared/widgets/top_nav_bar.dart';
import 'models/credits_record_item.dart';

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

  @override
  State<PointsHistoryScreen> createState() => _PointsHistoryScreenState();
}

class _PointsHistoryScreenState extends State<PointsHistoryScreen> {
  static const int _pageSize = 20;
  final ScrollController _scrollController = ScrollController();
  final List<CreditsRecordItem> _records = [];

  bool _loading = true;
  bool _loadingMore = false;
  bool _hasNext = true;
  String? _error;
  int _currentPage = 1;

  @override
  void initState() {
    super.initState();
    _scrollController.addListener(_onScroll);
    _loadRecords(refresh: true);
  }

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

  void _onScroll() {
    if (!_scrollController.hasClients ||
        _loadingMore ||
        !_hasNext ||
        _loading) {
      return;
    }
    final pos = _scrollController.position;
    if (pos.pixels >= pos.maxScrollExtent - 200) {
      _loadRecords(refresh: false);
    }
  }

  Future<void> _loadRecords({required bool refresh}) async {
    if (refresh) {
      setState(() {
        _loading = true;
        _error = null;
        _currentPage = 1;
        _hasNext = true;
      });
    } else {
      if (_loadingMore || !_hasNext) return;
      setState(() => _loadingMore = true);
    }

    try {
      await AuthService.loginComplete;
      final page = refresh ? 1 : _currentPage;
      final res = await UserApi.getCreditsPage(
        sentinel: ApiConfig.appId,
        trophy: page.toString(),
        heatmap: _pageSize.toString(),
      );
      if (!mounted) return;
      if (res.isSuccess && res.data is Map<String, dynamic>) {
        final data = res.data as Map<String, dynamic>;
        final intensify = data['intensify'] as List<dynamic>? ?? [];
        final list = intensify
            .whereType<Map<String, dynamic>>()
            .map(CreditsRecordItem.fromJson)
            .toList();
        final pages = (data['coordinate'] as num?)?.toInt() ?? page;
        final current = (data['empower'] as num?)?.toInt() ?? page;
        setState(() {
          if (refresh) {
            _records
              ..clear()
              ..addAll(list);
          } else {
            _records.addAll(list);
          }
          _currentPage = current + 1;
          _hasNext = current < pages;
          _loading = false;
          _loadingMore = false;
        });
      } else {
        setState(() {
          if (refresh) _records.clear();
          _loading = false;
          _loadingMore = false;
          _error = 'Unable to load points history right now. Please try again.';
        });
      }
    } catch (_) {
      if (!mounted) return;
      setState(() {
        if (refresh) _records.clear();
        _loading = false;
        _loadingMore = false;
        _error =
            'Something went wrong while loading points history. Please try again.';
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final points = UserCreditsData.of(context)?.creditsDisplay ?? '--';
    return Scaffold(
      backgroundColor: AppColors.background,
      appBar: const PreferredSize(
        preferredSize: Size.fromHeight(56),
        child: TopNavBar(
          title: 'Points History',
          showBackButton: true,
        ),
      ),
      body: _loading
          ? const Center(child: CircularProgressIndicator())
          : _error != null
              ? Center(
                  child: Padding(
                    padding:
                        const EdgeInsets.symmetric(horizontal: AppSpacing.xxl),
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        Text(
                          _error!,
                          textAlign: TextAlign.center,
                          style: AppTypography.bodyRegular.copyWith(
                            color: AppColors.textSecondary,
                          ),
                        ),
                        const SizedBox(height: AppSpacing.lg),
                        TextButton(
                          onPressed: () => _loadRecords(refresh: true),
                          child: const Text('Retry'),
                        ),
                      ],
                    ),
                  ),
                )
              : RefreshIndicator(
                  onRefresh: () => _loadRecords(refresh: true),
                  child: ListView(
                    controller: _scrollController,
                    physics: const AlwaysScrollableScrollPhysics(),
                    padding: const EdgeInsets.fromLTRB(
                      AppSpacing.screenPadding,
                      AppSpacing.xxl,
                      AppSpacing.screenPadding,
                      AppSpacing.screenPaddingLarge,
                    ),
                    children: [
                      _CurrentPointsCard(points: points),
                      const SizedBox(height: AppSpacing.xl),
                      if (_records.isEmpty)
                        Padding(
                          padding: const EdgeInsets.symmetric(
                            vertical: AppSpacing.screenPaddingLarge,
                          ),
                          child: Center(
                            child: Text(
                              'No history yet',
                              style: AppTypography.bodyRegular.copyWith(
                                color: AppColors.textSecondary,
                              ),
                            ),
                          ),
                        )
                      else
                        ..._records.map(
                          (item) => Padding(
                            padding:
                                const EdgeInsets.only(bottom: AppSpacing.md),
                            child: _HistoryRow(item: item),
                          ),
                        ),
                      if (_loadingMore)
                        const Padding(
                          padding:
                              EdgeInsets.symmetric(vertical: AppSpacing.md),
                          child: Center(
                            child: SizedBox(
                              width: 20,
                              height: 20,
                              child: CircularProgressIndicator(strokeWidth: 2),
                            ),
                          ),
                        ),
                    ],
                  ),
                ),
    );
  }
}

class _CurrentPointsCard extends StatelessWidget {
  const _CurrentPointsCard({required this.points});

  final String points;

  @override
  Widget build(BuildContext context) {
    return Container(
      padding: const EdgeInsets.symmetric(
        horizontal: AppSpacing.xl,
        vertical: AppSpacing.xl,
      ),
      decoration: BoxDecoration(
        color: AppColors.surface,
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: AppColors.border),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Current Points',
            style:
                AppTypography.caption.copyWith(color: AppColors.textSecondary),
          ),
          const SizedBox(height: AppSpacing.sm),
          Text(
            points,
            style: AppTypography.bodyLarge.copyWith(
              color: AppColors.textPrimary,
              fontSize: 34,
              fontWeight: FontWeight.w700,
            ),
          ),
        ],
      ),
    );
  }
}

class _HistoryRow extends StatelessWidget {
  const _HistoryRow({required this.item});

  final CreditsRecordItem item;

  @override
  Widget build(BuildContext context) {
    final isPositive = item.isIncrease;
    return Container(
      padding: const EdgeInsets.symmetric(
        horizontal: AppSpacing.xl,
        vertical: AppSpacing.lg,
      ),
      decoration: BoxDecoration(
        color: AppColors.surface,
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: AppColors.border),
      ),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          Text(
            _formatTime(item.createTime),
            style:
                AppTypography.caption.copyWith(color: AppColors.textSecondary),
          ),
          Text(
            item.deltaText,
            style: AppTypography.bodyMedium.copyWith(
              color: isPositive
                  ? const Color(0xFF16A34A)
                  : const Color(0xFFDC2626),
              fontWeight: FontWeight.w700,
            ),
          ),
        ],
      ),
    );
  }
}

String _formatTime(int raw) {
  if (raw <= 0) return '--';
  final dt = raw > 1000000000000
      ? DateTime.fromMillisecondsSinceEpoch(raw)
      : DateTime.fromMillisecondsSinceEpoch(raw * 1000);
  String two(int n) => n.toString().padLeft(2, '0');
  return '${dt.year}-${two(dt.month)}-${two(dt.day)} ${two(dt.hour)}:${two(dt.minute)}';
}