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 '../../core/widgets/empty_state.dart';
import '../../core/widgets/money_text.dart';
import '../../core/widgets/section_card.dart';
import '../portfolio/labels.dart' show formatQty, signColor;
import 'data/rebalance_api.dart';
import 'labels.dart';
import 'providers.dart';
import 'weights.dart';

/// Рекомендации: what to buy and sell to get back to the target weights.
///
/// Three things are marked explicitly, because without them the numbers mislead:
/// `within_band` (no action needed — the drift is inside the corridor the user set),
/// `blocked_by_cash` (the quantity was cut because the cash ran out), and a null
/// `suggested_qty` (there is no price, so no quantity can be computed — an em dash, not 0).
class RebalancePlanTab extends ConsumerWidget {
  const RebalancePlanTab({super.key});

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

    return RefreshIndicator(
      onRefresh: () async => ref.invalidate(rebalancePlanProvider),
      child: AsyncValueView(
        value: plan,
        onRetry: () => ref.invalidate(rebalancePlanProvider),
        data: (data) {
          if (data == null) {
            return const EmptyState(
              icon: Icons.balance,
              message: 'Портфель не выбран.',
            );
          }
          return ListView(
            padding: const EdgeInsets.all(16),
            children: [
              _Header(plan: data),
              if (data.warnings.isNotEmpty) ...[
                const SizedBox(height: 12),
                _Warnings(warnings: data.warnings),
              ],
              const SizedBox(height: 16),
              if (data.buckets.isEmpty)
                const Padding(
                  padding: EdgeInsets.only(top: 32),
                  child: EmptyState(
                    icon: Icons.balance,
                    message: 'Нечего показать: целевые веса по этому измерению не заданы.',
                  ),
                )
              else if (data.everythingWithinBand)
                Card(
                  color: Theme.of(context).colorScheme.secondaryContainer,
                  child: const ListTile(
                    leading: Icon(Icons.check_circle_outline),
                    title: Text('Все группы внутри коридора'),
                    subtitle: Text('Действий не требуется — отклонения меньше заданного допуска.'),
                  ),
                ),
              const SizedBox(height: 8),
              for (final b in data.buckets)
                Padding(
                  padding: const EdgeInsets.only(bottom: 12),
                  child: _BucketCard(dimension: data.dimension, bucket: b),
                ),
            ],
          );
        },
      ),
    );
  }
}

class _Header extends ConsumerWidget {
  const _Header({required this.plan});

  final RebalancePlan plan;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final whatIf = ref.watch(whatIfCashProvider);
    return SectionCard(
      title: 'Портфель',
      subtitle: plan.asOf == null ? null : 'на ${ruDate(plan.asOf!)}',
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Wrap(
            spacing: 24,
            runSpacing: 8,
            children: [
              _Figure(
                label: 'Стоимость',
                child: plan.totalValueRub == null
                    ? const Text('—')
                    : MoneyText(plan.totalValueRub!, currency: 'RUB'),
              ),
              _Figure(
                label: whatIf == null ? 'Доступно денег' : 'Доступно денег (what-if)',
                child: plan.cashAvailableRub == null
                    ? const Text('—')
                    : MoneyText(plan.cashAvailableRub!, currency: 'RUB'),
              ),
            ],
          ),
          const SizedBox(height: 12),
          _WhatIfCashField(current: whatIf),
        ],
      ),
    );
  }
}

class _Figure extends StatelessWidget {
  const _Figure({required this.label, required this.child});

  final String label;
  final Widget child;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      mainAxisSize: MainAxisSize.min,
      children: [
        Text(label, style: theme.textTheme.bodySmall),
        DefaultTextStyle(style: theme.textTheme.titleMedium!, child: child),
      ],
    );
  }
}

class _WhatIfCashField extends ConsumerStatefulWidget {
  const _WhatIfCashField({required this.current});

  final String? current;

  @override
  ConsumerState<_WhatIfCashField> createState() => _WhatIfCashFieldState();
}

class _WhatIfCashFieldState extends ConsumerState<_WhatIfCashField> {
  late final TextEditingController _controller =
      TextEditingController(text: widget.current ?? '');

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

  void _apply() {
    final text = _controller.text.trim().replaceAll(',', '.').replaceAll(' ', '');
    ref.read(whatIfCashProvider.notifier).state = text.isEmpty ? null : text;
  }

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        SizedBox(
          width: 220,
          child: TextField(
            controller: _controller,
            keyboardType: const TextInputType.numberWithOptions(decimal: true),
            decoration: const InputDecoration(
              labelText: 'Считать по другой сумме денег, ₽',
              isDense: true,
              helperText: 'пусто — реальный остаток на счетах',
            ),
            onSubmitted: (_) => _apply(),
          ),
        ),
        const SizedBox(width: 12),
        TextButton(onPressed: _apply, child: const Text('Пересчитать')),
      ],
    );
  }
}

class _Warnings extends StatelessWidget {
  const _Warnings({required this.warnings});

  final List<String> warnings;

  @override
  Widget build(BuildContext context) {
    return Card(
      color: Theme.of(context).colorScheme.tertiaryContainer,
      child: Padding(
        padding: const EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            for (final w in warnings)
              Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  const Icon(Icons.warning_amber_outlined, size: 16),
                  const SizedBox(width: 8),
                  Expanded(child: Text(w)),
                ],
              ),
          ],
        ),
      ),
    );
  }
}

class _BucketCard extends StatelessWidget {
  const _BucketCard({required this.dimension, required this.bucket});

  final String dimension;
  final RebalanceBucket bucket;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return SectionCard(
      title: bucketLabelForKey(dimension, bucket.bucket),
      subtitle: 'сейчас ${formatShareAsPercent(bucket.currentWeight)} · '
          'цель ${formatShareAsPercent(bucket.targetWeight)} · '
          'отклонение ${formatShareAsPercent(bucket.drift, signed: true)}',
      trailing: bucket.withinBand
          ? const _WithinBandChip()
          : (bucket.deltaValueRub == null
              ? const Text('—')
              : MoneyText(
                  bucket.deltaValueRub!,
                  currency: 'RUB',
                  style: TextStyle(color: signColor(context, bucket.deltaValueRub)),
                )),
      child: bucket.withinBand
          ? Text(
              'Внутри коридора — сделок не требуется.',
              style: theme.textTheme.bodySmall,
            )
          : bucket.trades.isEmpty
              ? Text(
                  'Сервер не предложил сделок по этой группе: '
                  'вероятно, у подходящих бумаг нет цены — см. предупреждения выше.',
                  style: theme.textTheme.bodySmall,
                )
              : Column(children: [for (final t in bucket.trades) TradeRow(trade: t)]),
    );
  }
}

class _WithinBandChip extends StatelessWidget {
  const _WithinBandChip();

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    return Tooltip(
      message: 'Отклонение не выходит за допуск (band) — действий не требуется',
      child: Chip(
        avatar: const Icon(Icons.check, size: 16),
        label: const Text('в коридоре'),
        backgroundColor: scheme.secondaryContainer,
        visualDensity: VisualDensity.compact,
      ),
    );
  }
}

/// One suggested trade. Public (unlike its neighbours) so the widget test can render the
/// `suggested_qty == null` case without standing up a provider container.
class TradeRow extends StatelessWidget {
  const TradeRow({required this.trade, super.key});

  final RebalanceTrade trade;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final isBuy = trade.action == 'buy';
    final noQty = trade.suggestedQty == null;

    final details = [
      if (trade.lot != null) 'лот ${trade.lot}',
      if (trade.price != null)
        'цена ${MoneyText.format(trade.price!, trade.priceCurrency ?? 'RUB')}',
    ].join(' · ');

    return ListTile(
      contentPadding: EdgeInsets.zero,
      dense: true,
      onTap: trade.instrumentId == null
          ? null
          : () => context.push('/portfolio/instrument/${trade.instrumentId}'),
      leading: Icon(
        isBuy ? Icons.add_circle_outline : Icons.remove_circle_outline,
        color: isBuy ? Theme.of(context).colorScheme.primary : theme.colorScheme.error,
      ),
      title: Row(
        children: [
          Flexible(child: Text(trade.title, overflow: TextOverflow.ellipsis)),
          const SizedBox(width: 8),
          if (trade.blockedByCash) const _BlockedByCashChip(),
        ],
      ),
      subtitle: Text(
        // a missing price is a reason, not a zero quantity
        noQty
            ? 'Количество не рассчитано: нет цены инструмента'
            : '${isBuy ? 'Купить' : 'Продать'} ${formatQty(trade.suggestedQty!)} шт.'
                '${details.isEmpty ? '' : ' · $details'}',
        style: theme.textTheme.bodySmall,
      ),
      trailing: noQty || trade.amountRub == null
          ? const Text('—')
          : MoneyText(trade.amountRub!, currency: 'RUB', style: theme.textTheme.titleSmall),
    );
  }
}

class _BlockedByCashChip extends StatelessWidget {
  const _BlockedByCashChip();

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    return Tooltip(
      message: 'Количество урезано: на счетах не хватает денег на полный объём',
      child: Chip(
        avatar: const Icon(Icons.account_balance_wallet_outlined, size: 16),
        label: const Text('не хватает денег'),
        backgroundColor: scheme.errorContainer,
        visualDensity: VisualDensity.compact,
      ),
    );
  }
}