import 'package:flutter/material.dart';

import '../../../core/utils/ru_date.dart';
import '../../../core/widgets/money_text.dart';
import '../../portfolio/labels.dart' show formatQty;
import '../data/imports_api.dart';

/// Сверка: the report's own positions and cash balances against what the ledger derives.
///
/// When everything matches this collapses to a single green line — a full table of zeroes
/// is noise. A mismatch is the whole point of the screen, so it stays expanded and red.
class ReconciliationCard extends StatelessWidget {
  const ReconciliationCard({required this.reconciliation, super.key});

  final Reconciliation reconciliation;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final asOf = reconciliation.asOf;
    final title = asOf == null ? 'Сверка' : 'Сверка на ${ruDate(asOf)}';

    if (reconciliation.isEmpty) {
      return Card(
        child: ListTile(
          leading: Icon(Icons.remove_circle_outline, color: theme.colorScheme.outline),
          title: Text(title),
          subtitle: const Text('В отчёте нет остатков для сверки'),
        ),
      );
    }

    if (reconciliation.matches) {
      return Card(
        child: ListTile(
          leading: const Icon(Icons.check_circle_outline, color: Colors.green),
          title: Text(title),
          subtitle: Text(
            'Всё сошлось: позиций ${reconciliation.positions.length}, '
            'остатков ${reconciliation.cash.length}',
            style: const TextStyle(color: Colors.green),
          ),
        ),
      );
    }

    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(Icons.error_outline, color: theme.colorScheme.error),
                const SizedBox(width: 8),
                Text(title, style: theme.textTheme.titleMedium),
              ],
            ),
            const SizedBox(height: 4),
            Text(
              'Отчёт и леджер разошлись. Импортировать можно, но расхождение стоит объяснить.',
              style: theme.textTheme.bodySmall,
            ),
            if (reconciliation.positions.isNotEmpty) ...[
              const SizedBox(height: 12),
              Text('Позиции', style: theme.textTheme.titleSmall),
              const SizedBox(height: 4),
              _ScrollableTable(
                columns: const ['Позиция', 'Из отчёта', 'Из леджера', 'Расхождение'],
                rows: [
                  for (final p in reconciliation.positions)
                    _Row(
                      cells: [
                        p.title,
                        _qty(p.qtyReport),
                        _qty(p.qtyDerived),
                        _qty(p.qtyDelta),
                      ],
                      highlight: !p.matches,
                    ),
                ],
              ),
            ],
            if (reconciliation.cash.isNotEmpty) ...[
              const SizedBox(height: 12),
              Text('Денежные остатки', style: theme.textTheme.titleSmall),
              const SizedBox(height: 4),
              _ScrollableTable(
                columns: const ['Валюта', 'Из отчёта', 'Из леджера', 'Расхождение'],
                rows: [
                  for (final c in reconciliation.cash)
                    _Row(
                      cells: [
                        c.currency,
                        _money(c.balanceReport, c.currency),
                        _money(c.balanceDerived, c.currency),
                        _money(c.delta, c.currency),
                      ],
                      highlight: !c.matches,
                    ),
                ],
              ),
            ],
          ],
        ),
      ),
    );
  }

  /// A quantity the ledger could not produce is an em dash, not a zero: an unknown position
  /// and an empty one are different findings.
  static String _qty(String? value) =>
      value == null || value.isEmpty ? '—' : formatQty(value);

  static String _money(String? value, String currency) =>
      value == null || value.isEmpty ? '—' : MoneyText.format(value, currency);
}

class _Row {
  const _Row({required this.cells, required this.highlight});
  final List<String> cells;
  final bool highlight;
}

/// A narrow table that scrolls sideways rather than overflowing on a phone.
class _ScrollableTable extends StatelessWidget {
  const _ScrollableTable({required this.columns, required this.rows});

  final List<String> columns;
  final List<_Row> rows;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return SingleChildScrollView(
      scrollDirection: Axis.horizontal,
      child: DataTable(
        columnSpacing: 24,
        headingRowHeight: 36,
        dataRowMinHeight: 36,
        dataRowMaxHeight: 48,
        columns: [for (final c in columns) DataColumn(label: Text(c))],
        rows: [
          for (final r in rows)
            DataRow(
              color: r.highlight
                  ? WidgetStatePropertyAll(theme.colorScheme.errorContainer.withValues(alpha: 0.4))
                  : null,
              cells: [
                for (final cell in r.cells)
                  DataCell(Text(
                    cell,
                    style: r.highlight
                        ? TextStyle(color: theme.colorScheme.error)
                        : null,
                  )),
              ],
            ),
        ],
      ),
    );
  }
}