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

import '../../core/api/api_client.dart';
import '../../core/cache/cached.dart';
import '../../core/utils/ru_date.dart';
import '../../core/widgets/async_value_view.dart';
import '../../core/widgets/empty_state.dart';
import 'data/benchmarks_api.dart';
import 'labels.dart';
import 'providers.dart';

final benchmarksApiProvider = Provider<BenchmarksApi>(
  (ref) => BenchmarksApi(ref.watch(apiProvider).dio),
);

/// Benchmark comparison for the current scope. Part of Портфель, not a screen of its own:
/// «на сколько я обогнал индекс» is a property of the portfolio, not a separate subject. See
/// `docs/ai/offline-cache.md`.
final benchmarkRowsProvider =
    FutureProvider.autoDispose<Cached<List<BenchmarkRow>>>((ref) async {
      final scope = ref.watch(scopeProvider);
      return ref.watch(benchmarksApiProvider).compare(scope: scope);
    });

/// The comparison block on Портфель.
///
/// Two things are always marked: a **price** index (no dividends — it understates the
/// holder's result by construction) and any non-zero `days_skipped` on either side (the two
/// returns then do not cover the same days, so the difference is not strictly like-for-like).
class BenchmarksCard extends ConsumerWidget {
  const BenchmarksCard({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final rows = ref.watch(benchmarkRowsProvider);

    return AsyncValueView(
      value: rows,
      onRetry: () => ref.invalidate(benchmarkRowsProvider),
      data: (cached) => cached.data.isEmpty
          ? const EmptyState(
              icon: Icons.compare_arrows,
              message: 'Бенчмарки не настроены — сравнивать не с чем.',
            )
          : Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                for (final row in cached.data)
                  Padding(
                    padding: const EdgeInsets.only(bottom: 12),
                    child: _PeriodBlock(row: row),
                  ),
              ],
            ),
    );
  }
}

class _PeriodBlock extends StatelessWidget {
  const _PeriodBlock({required this.row});

  final BenchmarkRow row;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            Text(periodLabel(row.period), style: theme.textTheme.titleSmall),
            const SizedBox(width: 8),
            if (row.dateFrom != null && row.dateTo != null)
              Text(
                '${ruDate(row.dateFrom!)} – ${ruDate(row.dateTo!)}',
                style: theme.textTheme.bodySmall?.copyWith(
                  color: theme.hintColor,
                ),
              ),
            const Spacer(),
            Text(
              'портфель ${formatPercent(row.portfolioTwr)}',
              style: theme.textTheme.titleSmall?.copyWith(
                color: signColor(context, row.portfolioTwr),
              ),
            ),
            if (row.portfolioDaysSkipped > 0) ...[
              const SizedBox(width: 6),
              _SkippedChip(days: row.portfolioDaysSkipped, side: 'портфеля'),
            ],
          ],
        ),
        const SizedBox(height: 6),
        for (final b in row.benchmarks) _BenchmarkRowView(result: b),
        if (row.benchmarksSkipDays)
          Padding(
            padding: const EdgeInsets.only(top: 6),
            child: Text(
              'У индекса нет котировок в часть дней окна — сравнение не строго день в день.',
              style: theme.textTheme.bodySmall?.copyWith(
                color: theme.hintColor,
              ),
            ),
          ),
        const Divider(height: 20),
      ],
    );
  }
}

class _BenchmarkRowView extends StatelessWidget {
  const _BenchmarkRowView({required this.result});

  final BenchmarkResult result;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 3),
      child: Row(
        children: [
          Text(result.code, style: theme.textTheme.bodyMedium),
          const SizedBox(width: 6),
          if (result.isPriceIndex) const _PriceIndexChip(),
          if (result.daysSkipped > 0) ...[
            const SizedBox(width: 6),
            _SkippedChip(days: result.daysSkipped, side: 'бенчмарка'),
          ],
          const Spacer(),
          Text(formatPercent(result.twr), style: theme.textTheme.bodyMedium),
          const SizedBox(width: 16),
          SizedBox(
            width: 92,
            child: Text(
              formatPercent(result.excess),
              textAlign: TextAlign.right,
              style: theme.textTheme.bodyMedium?.copyWith(
                color: signColor(context, result.excess),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class _PriceIndexChip extends StatelessWidget {
  const _PriceIndexChip();

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    return Tooltip(
      message:
          'Ценовой индекс: не учитывает дивиденды и систематически занижает '
          'результат держателя. Сравнение с ним — нижняя граница, а не эталон.',
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 1),
        decoration: BoxDecoration(
          color: scheme.errorContainer,
          borderRadius: BorderRadius.circular(6),
        ),
        child: Text(
          'ценовой индекс',
          style: Theme.of(context).textTheme.labelSmall,
        ),
      ),
    );
  }
}

class _SkippedChip extends StatelessWidget {
  const _SkippedChip({required this.days, required this.side});

  final int days;
  final String side;

  @override
  Widget build(BuildContext context) {
    return Tooltip(
      message:
          'В расчёте $side не учтено $days дн.: в эти дни у части позиций не было цены',
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          const Icon(Icons.info_outline, size: 14),
          const SizedBox(width: 2),
          Text('$days дн.', style: Theme.of(context).textTheme.labelSmall),
        ],
      ),
    );
  }
}