import 'dart:async';

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

import '../../core/utils/ru_date.dart';
import '../../core/widgets/empty_state.dart';
import '../../core/widgets/money_text.dart';
import '../accounts/providers.dart';
import '../categories/providers.dart';
import 'providers.dart';
import 'transaction_row.dart';

const _flowTypes = [
  FlowType.income,
  FlowType.expense,
  FlowType.internalTransfer,
  FlowType.savingsTransfer,
];

String _flowTypeLabel(FlowType t) => switch (t) {
  FlowType.income => 'Доход',
  FlowType.expense => 'Расход',
  FlowType.internalTransfer => 'Перевод',
  FlowType.savingsTransfer => 'В сбережения',
  FlowType.brokerExternalFlow => 'Брокер',
  FlowType.other => 'Прочее',
  FlowType.deleted => 'Удалено',
  FlowType.unknownDefaultOpenApi => 'Неизвестно',
};

/// Операции: filtered, paginated transaction list with infinite scroll and a
/// detail bottom sheet per row.
class TransactionsPage extends ConsumerStatefulWidget {
  const TransactionsPage({super.key});

  @override
  ConsumerState<TransactionsPage> createState() => _TransactionsPageState();
}

class _TransactionsPageState extends ConsumerState<TransactionsPage> {
  final _searchController = TextEditingController();
  final _scrollController = ScrollController();
  Timer? _debounce;

  @override
  void initState() {
    super.initState();
    _scrollController.addListener(_onScroll);
  }

  @override
  void dispose() {
    _debounce?.cancel();
    _searchController.dispose();
    _scrollController.removeListener(_onScroll);
    _scrollController.dispose();
    super.dispose();
  }

  void _onScroll() {
    if (_scrollController.position.pixels >
        _scrollController.position.maxScrollExtent - 200) {
      ref.read(transactionsControllerProvider.notifier).loadMore();
    }
  }

  void _onSearchChanged(String value) {
    _debounce?.cancel();
    _debounce = Timer(const Duration(milliseconds: 400), () {
      ref
          .read(transactionsControllerProvider.notifier)
          .setFilter(
            (f) =>
                f.copyWith(q: () => value.trim().isEmpty ? null : value.trim()),
          );
    });
  }

  Future<void> _pickDateRange() async {
    final filter = ref.read(transactionsControllerProvider.notifier).filter;
    final now = DateTime.now();
    final picked = await showDateRangePicker(
      context: context,
      firstDate: DateTime.utc(2015),
      lastDate: now,
      initialDateRange: filter.from != null && filter.to != null
          ? DateTimeRange(start: filter.from!, end: filter.to!)
          : null,
      helpText: 'Период',
    );
    if (picked != null) {
      ref
          .read(transactionsControllerProvider.notifier)
          .setFilter(
            (f) => f.copyWith(from: () => picked.start, to: () => picked.end),
          );
    }
  }

  void _clearDateRange() {
    ref
        .read(transactionsControllerProvider.notifier)
        .setFilter((f) => f.copyWith(from: () => null, to: () => null));
  }

  void _showDetail(TransactionOut t) {
    final accountNames = ref.read(accountNamesProvider);
    final categoryNames = ref.read(categoryNamesProvider);
    showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      builder: (context) => _TransactionDetailSheet(
        transaction: t,
        accountNames: accountNames,
        categoryNames: categoryNames,
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final state = ref.watch(transactionsControllerProvider);
    final controllerFilter = ref
        .watch(transactionsControllerProvider.notifier)
        .filter;
    final categoryNames = ref.watch(categoryNamesProvider);
    final accounts =
        ref.watch(accountsProvider).valueOrNull?.data ?? const <AccountOut>[];
    final categories =
        ref.watch(categoriesListProvider).valueOrNull ?? const <CategoryOut>[];

    return Scaffold(
      appBar: AppBar(title: const Text('Операции')),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 12, 16, 8),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                TextField(
                  controller: _searchController,
                  decoration: const InputDecoration(
                    prefixIcon: Icon(Icons.search),
                    hintText: 'Поиск по плательщику или комментарию',
                    isDense: true,
                    border: OutlineInputBorder(),
                  ),
                  onChanged: _onSearchChanged,
                ),
                const SizedBox(height: 8),
                Wrap(
                  spacing: 8,
                  runSpacing: 8,
                  crossAxisAlignment: WrapCrossAlignment.center,
                  children: [
                    InputChip(
                      avatar: const Icon(Icons.date_range, size: 18),
                      label: Text(
                        controllerFilter.from != null &&
                                controllerFilter.to != null
                            ? '${ruDate(controllerFilter.from!)} – ${ruDate(controllerFilter.to!)}'
                            : 'Период',
                      ),
                      onPressed: _pickDateRange,
                      onDeleted: controllerFilter.from != null
                          ? _clearDateRange
                          : null,
                    ),
                    SizedBox(
                      width: 180,
                      child: DropdownButtonFormField<int?>(
                        initialValue: controllerFilter.accountId,
                        isDense: true,
                        decoration: const InputDecoration(
                          labelText: 'Счёт',
                          isDense: true,
                        ),
                        items: [
                          const DropdownMenuItem(
                            value: null,
                            child: Text('Все счета'),
                          ),
                          for (final a in accounts)
                            DropdownMenuItem(value: a.id, child: Text(a.name)),
                        ],
                        onChanged: (v) => ref
                            .read(transactionsControllerProvider.notifier)
                            .setFilter((f) => f.copyWith(accountId: () => v)),
                      ),
                    ),
                    SizedBox(
                      width: 180,
                      child: DropdownButtonFormField<int?>(
                        initialValue: controllerFilter.categoryId,
                        isDense: true,
                        decoration: const InputDecoration(
                          labelText: 'Категория',
                          isDense: true,
                        ),
                        items: [
                          const DropdownMenuItem(
                            value: null,
                            child: Text('Все категории'),
                          ),
                          for (final c in categories)
                            DropdownMenuItem(value: c.id, child: Text(c.name)),
                        ],
                        onChanged: (v) => ref
                            .read(transactionsControllerProvider.notifier)
                            .setFilter((f) => f.copyWith(categoryId: () => v)),
                      ),
                    ),
                  ],
                ),
                const SizedBox(height: 8),
                Wrap(
                  spacing: 8,
                  children: [
                    ChoiceChip(
                      label: const Text('Все типы'),
                      selected: controllerFilter.flowType == null,
                      onSelected: (_) => ref
                          .read(transactionsControllerProvider.notifier)
                          .setFilter((f) => f.copyWith(flowType: () => null)),
                    ),
                    for (final ft in _flowTypes)
                      ChoiceChip(
                        label: Text(_flowTypeLabel(ft)),
                        selected: controllerFilter.flowType == ft,
                        onSelected: (_) => ref
                            .read(transactionsControllerProvider.notifier)
                            .setFilter((f) => f.copyWith(flowType: () => ft)),
                      ),
                  ],
                ),
              ],
            ),
          ),
          const Divider(height: 1),
          Expanded(child: _buildList(state, categoryNames)),
        ],
      ),
    );
  }

  Widget _buildList(TransactionsState state, Map<int, String> categoryNames) {
    if (state.loading && state.items.isEmpty) {
      return const Center(child: CircularProgressIndicator());
    }
    if (state.error != null && state.items.isEmpty) {
      return Center(
        child: Padding(
          padding: const EdgeInsets.all(24),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Icon(
                Icons.error_outline,
                color: Theme.of(context).colorScheme.error,
                size: 32,
              ),
              const SizedBox(height: 8),
              Text('${state.error}', textAlign: TextAlign.center),
              const SizedBox(height: 12),
              FilledButton.tonal(
                onPressed: () =>
                    ref.read(transactionsControllerProvider.notifier).refresh(),
                child: const Text('Повторить'),
              ),
            ],
          ),
        ),
      );
    }
    if (state.items.isEmpty) {
      return const EmptyState(
        icon: Icons.receipt_long_outlined,
        message: 'Операций не найдено — попробуйте изменить фильтры или выполните синхронизацию.',
      );
    }
    return RefreshIndicator(
      onRefresh: () =>
          ref.read(transactionsControllerProvider.notifier).refresh(),
      child: ListView.builder(
        controller: _scrollController,
        itemCount: state.items.length + 1,
        itemBuilder: (context, index) {
          if (index == state.items.length) {
            if (!state.hasMore) return const SizedBox(height: 24);
            return Padding(
              padding: const EdgeInsets.all(16),
              child: Center(
                child: state.loadingMore
                    ? const CircularProgressIndicator()
                    : TextButton(
                        onPressed: () => ref
                            .read(transactionsControllerProvider.notifier)
                            .loadMore(),
                        child: const Text('Ещё'),
                      ),
              ),
            );
          }
          final t = state.items[index];
          return TransactionRow(
            transaction: t,
            categoryName: t.categoryId != null
                ? categoryNames[t.categoryId]
                : null,
            onTap: () => _showDetail(t),
          );
        },
      ),
    );
  }
}

class _TransactionDetailSheet extends StatelessWidget {
  const _TransactionDetailSheet({
    required this.transaction,
    required this.accountNames,
    required this.categoryNames,
  });

  final TransactionOut transaction;
  final Map<int, String> accountNames;
  final Map<int, String> categoryNames;

  @override
  Widget build(BuildContext context) {
    final t = transaction;
    final rows = <(String, String)>[
      ('Дата', ruDate(t.date)),
      ('Плательщик', t.payee ?? '—'),
      if (t.payeeCanonical != null && t.payeeCanonical != t.payee)
        ('Канонический', t.payeeCanonical!),
      ('Комментарий', t.comment ?? '—'),
      (
        'Категория',
        t.categoryId != null
            ? (categoryNames[t.categoryId] ?? '#${t.categoryId}')
            : 'Без категории',
      ),
      ('Тип', _flowTypeLabel(t.flowType)),
      if (t.outcome != '0')
        (
          'Списание',
          '${MoneyText.format(t.outcome, t.outcomeCurrency ?? 'RUB')}'
              '${t.outcomeRub != null ? ' (${MoneyText.format(t.outcomeRub!, 'RUB')})' : ''}',
        ),
      if (t.income != '0')
        (
          'Зачисление',
          '${MoneyText.format(t.income, t.incomeCurrency ?? 'RUB')}'
              '${t.incomeRub != null ? ' (${MoneyText.format(t.incomeRub!, 'RUB')})' : ''}',
        ),
      if (t.outcomeAccountId != null)
        (
          'Счёт списания',
          accountNames[t.outcomeAccountId] ?? '#${t.outcomeAccountId}',
        ),
      if (t.incomeAccountId != null)
        (
          'Счёт зачисления',
          accountNames[t.incomeAccountId] ?? '#${t.incomeAccountId}',
        ),
      if (t.mcc != null) ('MCC', '${t.mcc}'),
      ('Удержание (hold)', t.hold ? 'да' : 'нет'),
      ('Разовая трата', t.isOneOff ? 'да' : 'нет'),
      if (t.tags.isNotEmpty)
        ('Теги', t.tags.map((id) => categoryNames[id] ?? '#$id').join(', ')),
      if (t.tripId != null) ('Поездка', '#${t.tripId}'),
      ('Источник (id)', t.sourceId),
    ];
    return SafeArea(
      child: Padding(
        padding: const EdgeInsets.fromLTRB(20, 16, 20, 24),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('Операция', style: Theme.of(context).textTheme.titleLarge),
            const SizedBox(height: 12),
            for (final (label, value) in rows)
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 4),
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    SizedBox(
                      width: 140,
                      child: Text(
                        label,
                        style: Theme.of(context).textTheme.bodySmall,
                      ),
                    ),
                    Expanded(child: Text(value)),
                  ],
                ),
              ),
          ],
        ),
      ),
    );
  }
}