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

import '../../core/utils/ru_date.dart';
import '../../core/widgets/async_value_view.dart';
import '../accounts/account_create_dialog.dart';
import '../portfolio/labels.dart' show eventKindLabels, formatQty;
import 'data/imports_api.dart';
import 'labels.dart';
import 'providers.dart';
import 'widgets/reconciliation_card.dart';
import 'widgets/sample_events_table.dart';

/// The preview of one uploaded report: what the parser found, how it lines up with the
/// ledger, and the one button that actually writes events. Nothing on this screen has
/// touched `event` yet — upload only parses.
class ImportPreviewPage extends ConsumerStatefulWidget {
  const ImportPreviewPage({required this.importId, super.key});

  final int importId;

  @override
  ConsumerState<ImportPreviewPage> createState() => _ImportPreviewPageState();
}

class _ImportPreviewPageState extends ConsumerState<ImportPreviewPage> {
  /// Chosen by the user when the server could not resolve `account_id` itself.
  int? _accountChoice;
  bool _confirmDuplicates = false;
  bool _busy = false;
  ImportResult? _result;

  void _snack(String message) =>
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text(message)));

  Future<void> _commit(ImportPreview preview) async {
    final accountId = preview.accountId ?? _accountChoice;
    if (accountId == null) return;
    setState(() => _busy = true);
    try {
      final result = await ref
          .read(importsApiProvider)
          .commit(
            preview.id,
            accountId: preview.accountId == null ? accountId : null,
            confirmDuplicates: _confirmDuplicates,
          );
      if (!mounted) return;
      setState(() => _result = result);
      // The ledger changed: every screen that counts events or values positions is stale.
      invalidateLedgerDependents(ref);
      ref.invalidate(importsListProvider);
      ref.invalidate(importPreviewProvider(preview.id));
      _snack(
        'Импортировано: создано ${result.eventsCreated}, '
        'обновлено ${result.eventsUpdated}, пропущено ${result.eventsSkipped}',
      );
    } catch (e) {
      if (!mounted) return;
      _snack(importErrorMessage(e));
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  Future<void> _delete(ImportPreview preview) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Удалить импорт?'),
        content: Text(
          'Файл «${preview.filename}» и разобранные строки будут удалены. '
          'События в леджере не создавались, так что удалять нечего.',
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: const Text('Отмена'),
          ),
          FilledButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text('Удалить'),
          ),
        ],
      ),
    );
    if (confirmed != true || !mounted) return;
    setState(() => _busy = true);
    try {
      await ref.read(importsApiProvider).delete(preview.id);
      if (!mounted) return;
      ref.invalidate(importsListProvider);
      context.go('/imports');
    } catch (e) {
      if (!mounted) return;
      _snack(importErrorMessage(e));
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final preview = ref.watch(importPreviewProvider(widget.importId));

    return Scaffold(
      appBar: AppBar(
        leading: IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: () => context.go('/imports'),
        ),
        title: const Text('Импорт отчёта'),
        actions: [
          IconButton(
            tooltip: 'Обновить',
            icon: const Icon(Icons.refresh),
            onPressed: () =>
                ref.invalidate(importPreviewProvider(widget.importId)),
          ),
        ],
      ),
      body: AsyncValueView(
        value: preview,
        onRetry: () => ref.invalidate(importPreviewProvider(widget.importId)),
        data: _buildBody,
      ),
    );
  }

  Widget _buildBody(ImportPreview p) {
    final theme = Theme.of(context);
    final accountId = p.accountId ?? _accountChoice;
    final recon = p.reconciliation;

    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        _header(p),
        if (p.duplicateOfId != null) ...[
          const SizedBox(height: 12),
          _banner(
            icon: Icons.copy_all_outlined,
            color: theme.colorScheme.secondary,
            title: 'Этот файл уже загружали',
            body:
                'Показан ранее созданный импорт №${p.duplicateOfId}. '
                'Повторная загрузка не создаёт новых событий.',
          ),
        ],
        if (p.isFailed) ...[
          const SizedBox(height: 12),
          _banner(
            icon: Icons.error_outline,
            color: theme.colorScheme.error,
            title: 'Файл не разобрался',
            body: p.error ?? 'Парсер не смог прочитать отчёт.',
          ),
        ],
        if (p.accountId == null && !p.isFailed) ...[
          const SizedBox(height: 12),
          _accountPicker(p),
        ],
        const SizedBox(height: 12),
        _countsCard(p),
        if (recon != null) ...[
          const SizedBox(height: 12),
          ReconciliationCard(reconciliation: recon),
        ],
        if (p.pendingInstruments.isNotEmpty) ...[
          const SizedBox(height: 12),
          _pendingCard(p),
        ],
        if (p.warnings.isNotEmpty) ...[
          const SizedBox(height: 12),
          _warningsCard(p),
        ],
        if (p.sampleEvents.isNotEmpty) ...[
          const SizedBox(height: 12),
          Card(
            child: Padding(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text('Строки отчёта', style: theme.textTheme.titleMedium),
                  const SizedBox(height: 4),
                  Text(
                    'Первые ${p.sampleEvents.length} из ${p.counts.lines}',
                    style: theme.textTheme.bodySmall,
                  ),
                  const SizedBox(height: 8),
                  SampleEventsTable(events: p.sampleEvents),
                ],
              ),
            ),
          ),
        ],
        if (_result != null) ...[
          const SizedBox(height: 12),
          _resultCard(_result!),
        ],
        const SizedBox(height: 16),
        _actions(p, accountId),
        const SizedBox(height: 32),
      ],
    );
  }

  Widget _header(ImportPreview p) {
    final theme = Theme.of(context);
    final period = p.periodFrom != null && p.periodTo != null
        ? '${ruDate(p.periodFrom!)} – ${ruDate(p.periodTo!)}'
        : 'период не определён';
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Expanded(
                  child: Text(p.filename, style: theme.textTheme.titleMedium),
                ),
                parseStatusChip(context, p.parseStatus),
              ],
            ),
            const SizedBox(height: 8),
            _kv('Брокер', brokerLabel(p.broker)),
            _kv('Период', period),
            _kv(
              'Счёт',
              p.accountName ??
                  (p.accountId != null
                      ? '#${p.accountId}'
                      : 'не определён по отчёту'),
            ),
            if (p.accountExternalId != null)
              _kv('Счёт в отчёте', p.accountExternalId!),
            if (p.parserName != null)
              _kv('Парсер', '${p.parserName} v${p.parserVersion ?? '1'}'),
            if (p.sizeBytes != null) _kv('Размер', formatBytes(p.sizeBytes)),
            if (p.uploadedAt != null)
              _kv('Загружен', ruDate(p.uploadedAt!.toLocal())),
            if (p.committedAt != null)
              _kv('Импортирован', ruDate(p.committedAt!.toLocal())),
          ],
        ),
      ),
    );
  }

  Future<void> _createAccountFromReport(ImportPreview p) async {
    final created = await showAccountCreateDialog(
      context,
      broker: brokerFromImportKey(p.broker),
      sourceId: p.accountExternalId,
      name: p.accountExternalId == null
          ? null
          : '${brokerLabel(p.broker)} ${p.accountExternalId}',
    );
    if (created == null || !mounted) return;
    // refetch first: the dropdown only accepts a value that is among the server's suggestions
    ref.invalidate(importPreviewProvider(widget.importId));
    await ref.read(importPreviewProvider(widget.importId).future);
    if (mounted) setState(() => _accountChoice = created.id);
  }

  Widget _accountPicker(ImportPreview p) {
    final theme = Theme.of(context);
    return Card(
      color: theme.colorScheme.errorContainer,
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(
                  Icons.account_balance_outlined,
                  color: theme.colorScheme.onErrorContainer,
                ),
                const SizedBox(width: 8),
                Expanded(
                  child: Text(
                    'Счёт не определён',
                    style: theme.textTheme.titleMedium?.copyWith(
                      color: theme.colorScheme.onErrorContainer,
                    ),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 4),
            Text(
              p.accountSuggestions.isEmpty
                  ? 'В отчёте номер счёта ${p.accountExternalId ?? '—'}, но подходящего '
                        'счёта в базе нет. Создайте счёт по данным из отчёта.'
                  : 'Выберите счёт, в который писать события, или создайте новый. '
                        'Без счёта импорт недоступен.',
              style: TextStyle(color: theme.colorScheme.onErrorContainer),
            ),
            const SizedBox(height: 8),
            OutlinedButton.icon(
              onPressed: () => _createAccountFromReport(p),
              icon: const Icon(Icons.add),
              label: const Text('Создать счёт из отчёта'),
            ),
            if (p.accountSuggestions.isNotEmpty) ...[
              const SizedBox(height: 12),
              DropdownButtonFormField<int>(
                initialValue: _accountChoice,
                isExpanded: true,
                decoration: const InputDecoration(
                  labelText: 'Счёт',
                  filled: true,
                  border: OutlineInputBorder(),
                ),
                items: [
                  for (final s in p.accountSuggestions)
                    DropdownMenuItem(
                      value: s.id,
                      child: Text(
                        [
                          s.name,
                          if (s.broker != null) brokerLabel(s.broker),
                          if (s.sourceId != null) s.sourceId!,
                        ].join(' · '),
                      ),
                    ),
                ],
                onChanged: (v) => setState(() => _accountChoice = v),
              ),
            ],
          ],
        ),
      ),
    );
  }

  Widget _countsCard(ImportPreview p) {
    final theme = Theme.of(context);
    final c = p.counts;
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('Что нашлось', style: theme.textTheme.titleMedium),
            const SizedBox(height: 12),
            Wrap(
              spacing: 12,
              runSpacing: 12,
              children: [
                _stat('Строк', c.lines),
                _stat('Событий', c.eventsTotal),
                _stat('Новых', c.eventsNew, color: Colors.green),
                _stat(
                  'Дубликатов',
                  c.eventsDuplicate,
                  color: c.eventsDuplicate > 0
                      ? theme.colorScheme.secondary
                      : null,
                  hint: 'Уже есть в леджере: будут обновлены, а не продублированы',
                ),
                _stat(
                  'Shadow',
                  c.eventsShadow,
                  hint: 'Не первичный источник — в аналитику не идут',
                ),
                _stat(
                  'Ждут инструмента',
                  c.eventsPending,
                  color: c.eventsPending > 0 ? theme.colorScheme.error : null,
                  hint: 'Инструмент не распознан, события останутся в статусе pending',
                ),
              ],
            ),
            if (c.byKind.isNotEmpty) ...[
              const SizedBox(height: 16),
              Text('По типам', style: theme.textTheme.titleSmall),
              const SizedBox(height: 8),
              Wrap(
                spacing: 8,
                runSpacing: 8,
                children: [
                  for (final e in c.byKind.entries)
                    Chip(
                      visualDensity: VisualDensity.compact,
                      label: Text(
                        '${eventKindLabels[e.key] ?? e.key}: ${e.value}',
                      ),
                    ),
                ],
              ),
            ],
          ],
        ),
      ),
    );
  }

  Widget _pendingCard(ImportPreview p) {
    final theme = Theme.of(context);
    return Card(
      child: Padding(
        padding: const EdgeInsets.fromLTRB(16, 16, 16, 8),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              'Нераспознанные инструменты (${p.pendingInstruments.length})',
              style: theme.textTheme.titleMedium,
            ),
            const SizedBox(height: 4),
            Text(
              'Сервер не угадывает инструмент. Пока вы не привяжете эти строки вручную, '
              'их события останутся в статусе pending и не попадут в аналитику.',
              style: theme.textTheme.bodySmall,
            ),
            const SizedBox(height: 8),
            for (final pi in p.pendingInstruments)
              ListTile(
                contentPadding: EdgeInsets.zero,
                dense: true,
                title: Text(pi.title),
                subtitle: Text(
                  [
                    if (pi.isin != null) 'ISIN ${pi.isin}',
                    'встречается ${pi.occurrences}',
                    if (pi.sampleQuantity != null)
                      'кол-во ${formatQty(pi.sampleQuantity!)}',
                  ].join(' · '),
                ),
              ),
            Align(
              alignment: Alignment.centerRight,
              child: TextButton.icon(
                onPressed: () => context.go('/instruments/pending'),
                icon: const Icon(Icons.open_in_new, size: 18),
                label: const Text('К резолву инструментов'),
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _warningsCard(ImportPreview p) {
    final theme = Theme.of(context);
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(
                  Icons.warning_amber_outlined,
                  color: theme.colorScheme.tertiary,
                ),
                const SizedBox(width: 8),
                Text('Предупреждения', style: theme.textTheme.titleMedium),
              ],
            ),
            const SizedBox(height: 8),
            for (final w in p.warnings)
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 2),
                child: Text('• $w'),
              ),
          ],
        ),
      ),
    );
  }

  Widget _resultCard(ImportResult r) {
    final theme = Theme.of(context);
    return Card(
      color: theme.colorScheme.secondaryContainer,
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('Результат импорта', style: theme.textTheme.titleMedium),
            const SizedBox(height: 8),
            _kv('Создано событий', '${r.eventsCreated}'),
            _kv('Обновлено', '${r.eventsUpdated}'),
            _kv('Пропущено', '${r.eventsSkipped}'),
            if (r.eventsShadow > 0) _kv('Shadow', '${r.eventsShadow}'),
            if (r.pendingInstruments > 0)
              _kv('Ждут инструмента', '${r.pendingInstruments}'),
            _kv('Метрики пересчитаны', r.metricsRefreshed ? 'да' : 'нет'),
          ],
        ),
      ),
    );
  }

  Widget _actions(ImportPreview p, int? accountId) {
    final canCommit =
        !p.isCommitted && !p.isFailed && accountId != null && !_busy;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        if (p.counts.eventsDuplicate > 0 && !p.isCommitted)
          CheckboxListTile(
            contentPadding: EdgeInsets.zero,
            value: _confirmDuplicates,
            onChanged: (v) => setState(() => _confirmDuplicates = v ?? false),
            title: const Text('Обновлять дубликаты'),
            subtitle: Text(
              'Перезаписать ${p.counts.eventsDuplicate} событий, '
              'которые уже есть в леджере',
            ),
          ),
        Wrap(
          spacing: 12,
          runSpacing: 12,
          children: [
            FilledButton.icon(
              onPressed: canCommit ? () => _commit(p) : null,
              icon: _busy
                  ? const SizedBox(
                      width: 18,
                      height: 18,
                      child: CircularProgressIndicator(strokeWidth: 2),
                    )
                  : const Icon(Icons.playlist_add_check),
              label: Text(p.isCommitted ? 'Уже импортирован' : 'Импортировать'),
            ),
            if (p.canDelete)
              OutlinedButton.icon(
                onPressed: _busy ? null : () => _delete(p),
                icon: const Icon(Icons.delete_outline),
                label: const Text('Удалить'),
              ),
          ],
        ),
        if (accountId == null && !p.isFailed)
          Padding(
            padding: const EdgeInsets.only(top: 8),
            child: Text(
              'Импорт недоступен, пока не выбран счёт.',
              style: TextStyle(color: Theme.of(context).colorScheme.error),
            ),
          ),
      ],
    );
  }

  Widget _banner({
    required IconData icon,
    required Color color,
    required String title,
    required String body,
  }) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Icon(icon, color: color),
            const SizedBox(width: 12),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    title,
                    style: Theme.of(context).textTheme.titleSmall
                        ?.copyWith(color: color),
                  ),
                  const SizedBox(height: 4),
                  Text(body),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _stat(String label, int value, {Color? color, String? hint}) {
    final theme = Theme.of(context);
    final tile = Container(
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
      decoration: BoxDecoration(
        color: theme.colorScheme.surfaceContainerHighest.withValues(alpha: 0.5),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(label, style: theme.textTheme.bodySmall),
          Text(
            '$value',
            style: theme.textTheme.titleLarge?.copyWith(color: color),
          ),
        ],
      ),
    );
    return hint == null ? tile : Tooltip(message: hint, child: tile);
  }

  Widget _kv(String label, String value) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 2),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          SizedBox(
            width: 140,
            child: Text(label, style: Theme.of(context).textTheme.bodySmall),
          ),
          Expanded(child: Text(value)),
        ],
      ),
    );
  }
}