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

import '../../core/theme/chart_colors.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 'labels.dart';
import 'providers.dart';

double _d(String s) => Decimal.parse(s).toDouble();

/// The instrument card: the position, the lots behind its cost, every event that touched it
/// and the price history behind its value — the screen that answers "where does this number
/// come from" when a reconciliation finding points here.
class InstrumentPage extends ConsumerWidget {
  const InstrumentPage({required this.instrumentId, super.key});

  final int instrumentId;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final detail = ref.watch(instrumentProvider(instrumentId));

    return Scaffold(
      appBar: AppBar(
        title: Text(detail.valueOrNull?.instrument.ticker ??
            detail.valueOrNull?.instrument.name ??
            'Инструмент'),
      ),
      body: AsyncValueView(
        value: detail,
        onRetry: () => ref.invalidate(instrumentProvider(instrumentId)),
        data: (d) => ListView(
          padding: const EdgeInsets.all(16),
          children: [
            _Header(instrument: d.instrument, holding: d.holding),
            const SizedBox(height: 16),
            _Section(
              title: 'Цена',
              child: d.prices.isEmpty
                  ? const EmptyState(
                      icon: Icons.show_chart,
                      message: 'Цен нет — стоимость позиции неизвестна.',
                    )
                  : _PriceChart(prices: d.prices),
            ),
            const SizedBox(height: 16),
            _Section(
              title: 'Лоты',
              child: d.lots.isEmpty
                  ? const EmptyState(icon: Icons.layers_outlined, message: 'Лотов нет.')
                  : _LotsTable(lots: d.lots),
            ),
            const SizedBox(height: 16),
            _Section(
              title: 'События',
              child: d.events.isEmpty
                  ? const EmptyState(icon: Icons.receipt_long, message: 'Событий нет.')
                  : _EventsTable(events: d.events),
            ),
          ],
        ),
      ),
    );
  }
}

class _Header extends StatelessWidget {
  const _Header({required this.instrument, required this.holding});

  final InstrumentOut instrument;
  final HoldingOut? holding;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final facts = <String>[
      assetClassLabel(instrument.assetClass),
      if (instrument.board != null) instrument.board!,
      if (instrument.isin != null) instrument.isin!,
      if (instrument.country != null) instrument.country!,
      instrument.currency,
    ];
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(instrument.name, style: theme.textTheme.titleLarge),
            const SizedBox(height: 4),
            Text(facts.join(' · '),
                style: theme.textTheme.bodySmall?.copyWith(color: theme.hintColor)),
            const SizedBox(height: 16),
            if (holding == null)
              Text('Позиция закрыта', style: theme.textTheme.bodyMedium)
            else
              _HoldingFacts(holding: holding!),
          ],
        ),
      ),
    );
  }
}

class _HoldingFacts extends StatelessWidget {
  const _HoldingFacts({required this.holding});

  final HoldingOut holding;

  @override
  Widget build(BuildContext context) {
    final h = holding;
    return Wrap(
      spacing: 24,
      runSpacing: 12,
      children: [
        _Fact(label: 'Количество', value: Text(formatQty(h.qty))),
        _Fact(
          label: 'Средняя цена',
          value: h.avgCost == null
              ? const Text('—')
              : MoneyText(h.avgCost!, currency: h.costCurrency ?? h.currency),
        ),
        _Fact(
          label: 'Текущая цена',
          value: Row(
            mainAxisSize: MainAxisSize.min,
            children: [
              h.marketPrice == null
                  ? const Text('—')
                  : MoneyText(h.marketPrice!, currency: h.priceCurrency ?? h.currency),
              const SizedBox(width: 6),
              PriceStatusChip(status: h.priceStatus, priceDate: h.priceDate),
            ],
          ),
        ),
        _Fact(
          label: 'Стоимость',
          value: h.valueRub == null ? const Text('—') : MoneyText(h.valueRub!, currency: 'RUB'),
        ),
        _Fact(
          label: 'Нереализованная',
          value: h.unrealizedPnlRub == null
              ? const Text('—')
              : MoneyText(
                  h.unrealizedPnlRub!,
                  currency: 'RUB',
                  style: TextStyle(color: signColor(context, h.unrealizedPnlRub)),
                ),
        ),
        _Fact(
          label: 'Реализованная',
          value: MoneyText(h.realizedPnlRub ?? '0', currency: 'RUB'),
        ),
        _Fact(label: 'Выплаты', value: MoneyText(h.incomeRub ?? '0', currency: 'RUB')),
        _Fact(
          label: 'XIRR',
          value: Text(
            formatPercent(h.xirr),
            style: TextStyle(color: signColor(context, h.xirr)),
          ),
        ),
        if (h.firstBuyDate != null)
          _Fact(
            label: 'В портфеле',
            value: Text('${h.daysHeld ?? 0} дн. с ${ruDate(h.firstBuyDate!)}'),
          ),
        if (_d(h.ldvEligibleQty) > 0)
          _Fact(label: 'Под ЛДВ', value: Text(formatQty(h.ldvEligibleQty))),
      ],
    );
  }
}

class _Fact extends StatelessWidget {
  const _Fact({required this.label, required this.value});

  final String label;
  final Widget value;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(label, style: theme.textTheme.bodySmall?.copyWith(color: theme.hintColor)),
        const SizedBox(height: 2),
        DefaultTextStyle(style: theme.textTheme.titleSmall!, child: value),
      ],
    );
  }
}

class _PriceChart extends StatelessWidget {
  const _PriceChart({required this.prices});

  final List<PricePoint> prices;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return SizedBox(
      height: 200,
      child: LineChart(
        LineChartData(
          gridData: const FlGridData(show: true, drawVerticalLine: false),
          borderData: FlBorderData(show: false),
          titlesData: FlTitlesData(
            topTitles: const AxisTitles(),
            rightTitles: const AxisTitles(),
            leftTitles: const AxisTitles(
              sideTitles: SideTitles(showTitles: true, reservedSize: 52),
            ),
            bottomTitles: AxisTitles(
              sideTitles: SideTitles(
                showTitles: true,
                reservedSize: 28,
                interval: (prices.length / 4).clamp(1, double.infinity),
                getTitlesWidget: (value, meta) {
                  final i = value.round();
                  if (i < 0 || i >= prices.length) return const SizedBox.shrink();
                  return Text(ruMonthYearShort(prices[i].d), style: theme.textTheme.bodySmall);
                },
              ),
            ),
          ),
          lineBarsData: [
            LineChartBarData(
              spots: [
                for (var i = 0; i < prices.length; i++)
                  FlSpot(i.toDouble(), _d(prices[i].close)),
              ],
              isCurved: false,
              color: ChartColors.slot1Blue,
              barWidth: 2,
              dotData: const FlDotData(show: false),
            ),
          ],
        ),
      ),
    );
  }
}

class _LotsTable extends StatelessWidget {
  const _LotsTable({required this.lots});

  final List<LotOut> lots;

  @override
  Widget build(BuildContext context) {
    final headerStyle = Theme.of(context).textTheme.labelMedium;
    return SingleChildScrollView(
      scrollDirection: Axis.horizontal,
      child: DataTable(
        columns: [
          DataColumn(label: Text('Открыт', style: headerStyle)),
          DataColumn(label: Text('Куплено', style: headerStyle), numeric: true),
          DataColumn(label: Text('Осталось', style: headerStyle), numeric: true),
          DataColumn(label: Text('Цена', style: headerStyle), numeric: true),
          DataColumn(label: Text('Стоимость, ₽', style: headerStyle), numeric: true),
          DataColumn(label: Text('Закрыт', style: headerStyle)),
        ],
        rows: [
          for (final lot in lots)
            DataRow(
              cells: [
                DataCell(Text(ruDate(lot.openDate))),
                DataCell(Text(formatQty(lot.qtyOpen))),
                DataCell(Text(formatQty(lot.qtyRemaining))),
                DataCell(MoneyText(lot.costPerUnit, currency: lot.costCurrency)),
                DataCell(lot.costTotalRub == null
                    ? const Text('—')
                    : MoneyText(lot.costTotalRub!, currency: 'RUB')),
                DataCell(Text(lot.closedAt == null ? '—' : ruDate(lot.closedAt!))),
              ],
            ),
        ],
      ),
    );
  }
}

class _EventsTable extends StatelessWidget {
  const _EventsTable({required this.events});

  final List<EventOut> events;

  @override
  Widget build(BuildContext context) {
    final headerStyle = Theme.of(context).textTheme.labelMedium;
    return SingleChildScrollView(
      scrollDirection: Axis.horizontal,
      child: DataTable(
        columns: [
          DataColumn(label: Text('Дата', style: headerStyle)),
          DataColumn(label: Text('Тип', style: headerStyle)),
          DataColumn(label: Text('Кол-во', style: headerStyle), numeric: true),
          DataColumn(label: Text('Цена', style: headerStyle), numeric: true),
          DataColumn(label: Text('Сумма', style: headerStyle), numeric: true),
          DataColumn(label: Text('Описание', style: headerStyle)),
        ],
        rows: [
          for (final e in events)
            DataRow(
              cells: [
                DataCell(Text(ruDate(e.tradeDate))),
                DataCell(Row(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Text(eventKindLabel(e.kind)),
                    if (e.externalFlow) ...[
                      const SizedBox(width: 4),
                      const Tooltip(
                        message: 'Внешний поток — учитывается в XIRR',
                        child: Icon(Icons.swap_vert, size: 14),
                      ),
                    ],
                  ],
                )),
                DataCell(Text(e.quantity == null ? '—' : formatQty(e.quantity!))),
                DataCell(e.price == null
                    ? const Text('—')
                    : MoneyText(e.price!, currency: e.priceCurrency ?? e.currency)),
                DataCell(MoneyText(
                  e.amount,
                  currency: e.currency,
                  style: TextStyle(color: signColor(context, e.amount)),
                )),
                DataCell(SizedBox(
                  width: 260,
                  child: Text(e.description ?? '', overflow: TextOverflow.ellipsis),
                )),
              ],
            ),
        ],
      ),
    );
  }
}

class _Section extends StatelessWidget {
  const _Section({required this.title, required this.child});

  final String title;
  final Widget child;

  @override
  Widget build(BuildContext context) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(title, style: Theme.of(context).textTheme.titleMedium),
            const SizedBox(height: 12),
            child,
          ],
        ),
      ),
    );
  }
}