/// Searchable transaction list with month heatmap and money in/out totals.
library;

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

import '../models/bank.dart';
import '../models/transaction_meta.dart';
import '../providers/bank_provider.dart';
import '../providers/tx_meta_provider.dart';
import '../utils/connect_bank.dart';
import '../utils/helpers.dart';
import '../utils/navigation.dart';
import '../utils/tx_calendar.dart';
import '../widgets/empty_state.dart';
import '../widgets/loading_view.dart';
import '../widgets/responsive_body.dart';
import '../widgets/tx_heatmap.dart';
import 'transaction_detail_screen.dart';

class TransactionsScreen extends StatefulWidget {
  const TransactionsScreen({super.key});

  @override
  State<TransactionsScreen> createState() => _TransactionsScreenState();
}

class _TransactionsScreenState extends State<TransactionsScreen> {
  final _searchController = TextEditingController();
  String _query = '';
  DateTime _month = monthStart(DateTime.now());
  DateTime? _selectedDay;
  var _searchInMonthOnly = false;
  final Set<TxCategory> _categoryFilters = {};

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

  bool get _isSearching =>
      _query.trim().isNotEmpty || _categoryFilters.isNotEmpty;

  void _goMonth(int delta) {
    final next = addMonths(_month, delta);
    final current = monthStart(DateTime.now());
    if (delta > 0 && next.isAfter(current)) return;
    setState(() {
      _month = next.isAfter(current) ? current : next;
      _selectedDay = null;
    });
  }

  DateTime? _txDate(BankTransaction tx) => DateTime.tryParse(tx.date);

  bool _inCalendarScope(BankTransaction tx) {
    final date = _txDate(tx);
    if (date == null) return false;
    if (_selectedDay != null) return isSameDay(date, _selectedDay!);
    return isSameMonth(date, _month);
  }

  bool _inMonth(BankTransaction tx) {
    final date = _txDate(tx);
    if (date == null) return false;
    return isSameMonth(date, _month);
  }

  Future<void> _pickCategories(List<TxCategory> available) async {
    if (available.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('No categories in use yet')),
      );
      return;
    }

    final selected = Set<TxCategory>.of(_categoryFilters);
    await showModalBottomSheet<void>(
      context: context,
      showDragHandle: true,
      builder: (sheetContext) {
        return StatefulBuilder(
          builder: (context, setSheetState) {
            return SafeArea(
              child: Padding(
                padding: const EdgeInsets.fromLTRB(16, 0, 16, 24),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    Text(
                      'Filter by category',
                      style: Theme.of(context).textTheme.titleMedium,
                    ),
                    const SizedBox(height: 12),
                    Wrap(
                      spacing: 8,
                      runSpacing: 8,
                      children: [
                        for (final category in available)
                          FilterChip(
                            avatar: Icon(
                              category.icon,
                              size: 16,
                              color: category.color,
                            ),
                            label: Text(category.label),
                            selected: selected.contains(category),
                            onSelected: (value) {
                              setSheetState(() {
                                if (value) {
                                  selected.add(category);
                                } else {
                                  selected.remove(category);
                                }
                              });
                            },
                          ),
                      ],
                    ),
                    const SizedBox(height: 16),
                    FilledButton(
                      onPressed: () {
                        setState(() {
                          _categoryFilters
                            ..clear()
                            ..addAll(selected);
                        });
                        Navigator.pop(sheetContext);
                      },
                      child: const Text('Apply'),
                    ),
                  ],
                ),
              ),
            );
          },
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    final bank = context.watch<BankController>();

    return Scaffold(
      appBar: AppBar(
        title: const Text('Transactions'),
        actions: bankAppBarActions(
          context: context,
          onRefresh: bank.refresh,
          refreshing: bank.isLoading,
        ),
      ),
      body: RefreshIndicator(
        onRefresh: bank.refresh,
        child: ResponsiveBody(
          child: _buildBody(context, bank),
        ),
      ),
    );
  }

  Widget _buildBody(BuildContext context, BankController bank) {
    final metaController = context.watch<TxMetaController>();
    final theme = Theme.of(context);
    final colors = theme.colorScheme;

    if (bank.isLoading && bank.transactions.isEmpty) {
      return const LoadingView(message: 'Loading transactions…');
    }

    if (!bank.isLinked) {
      return ListView(
        physics: const AlwaysScrollableScrollPhysics(),
        children: [
          EmptyState(
            icon: Icons.receipt_long_outlined,
            title: 'No transactions yet',
            message: bank.error ??
                'Link your bank from Home to load recent activity.',
            actionLabel: bank.isConnecting ? 'Opening…' : 'Connect bank',
            onAction: () => runConnectBank(context, bank),
          ),
        ],
      );
    }

    if (bank.error != null && bank.transactions.isEmpty) {
      return ListView(
        physics: const AlwaysScrollableScrollPhysics(),
        children: [
          EmptyState(
            icon: Icons.error_outline,
            title: 'Could not load transactions',
            message: bank.error!,
            actionLabel: 'Retry',
            onAction: bank.refresh,
          ),
        ],
      );
    }

    if (bank.transactions.isEmpty) {
      return ListView(
        physics: const AlwaysScrollableScrollPhysics(),
        children: const [
          EmptyState(
            icon: Icons.inbox_outlined,
            title: 'No recent activity',
            message: 'The backend returned an empty transaction list.',
          ),
        ],
      );
    }

    final nowMonth = monthStart(DateTime.now());
    final monthDates = <DateTime>[
      for (final tx in bank.transactions)
        if (_txDate(tx) != null && isSameMonth(_txDate(tx)!, _month))
          dateOnly(_txDate(tx)!),
    ];
    final counts = txCountsByDay(monthDates);

    final calendarScoped = [
      for (final tx in bank.transactions)
        if (_inCalendarScope(tx)) tx,
    ];

    final searchPool = !_isSearching
        ? calendarScoped
        : _searchInMonthOnly
            ? [
                for (final tx in bank.transactions)
                  if (_inMonth(tx)) tx,
              ]
            : bank.transactions;

    final filtered = metaController.search(
      searchPool,
      _query,
      categories: _categoryFilters,
    );

    var moneyOut = 0.0;
    var moneyIn = 0.0;
    for (final tx in calendarScoped) {
      if (tx.amount < 0) {
        moneyOut += tx.amount.abs();
      } else if (tx.amount > 0) {
        moneyIn += tx.amount;
      }
    }
    final currency = bank.balance?.currency ??
        (bank.transactions.isNotEmpty
            ? bank.transactions.first.currency
            : 'EUR');
    final usedCategories = metaController.usedCategories(bank.transactions);

    return ListView(
      physics: const AlwaysScrollableScrollPhysics(),
      padding: const EdgeInsets.only(bottom: 32),
      children: [
        Padding(
          padding: const EdgeInsets.only(top: 8, bottom: 4),
          child: Row(
            children: [
              Expanded(
                child: TextField(
                  controller: _searchController,
                  textInputAction: TextInputAction.search,
                  decoration: InputDecoration(
                    hintText: 'Search description, notes…',
                    prefixIcon: IconButton(
                      tooltip: 'Categories',
                      onPressed: () => _pickCategories(usedCategories),
                      icon: Icon(
                        Icons.search,
                        color: _categoryFilters.isEmpty
                            ? null
                            : colors.primary,
                      ),
                    ),
                    suffixIcon: _query.isEmpty
                        ? null
                        : IconButton(
                            tooltip: 'Clear',
                            onPressed: () {
                              _searchController.clear();
                              setState(() => _query = '');
                            },
                            icon: const Icon(Icons.clear),
                          ),
                  ),
                  onChanged: (value) => setState(() => _query = value),
                ),
              ),
              const SizedBox(width: 4),
              Tooltip(
                message: 'Search only in calendar month',
                child: Row(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Checkbox(
                      value: _searchInMonthOnly,
                      onChanged: (value) {
                        setState(() => _searchInMonthOnly = value ?? false);
                      },
                    ),
                    Text('Month', style: theme.textTheme.labelMedium),
                  ],
                ),
              ),
            ],
          ),
        ),
        if (_categoryFilters.isNotEmpty)
          Padding(
            padding: const EdgeInsets.only(bottom: 8),
            child: Wrap(
              spacing: 8,
              runSpacing: 8,
              children: [
                for (final category in _categoryFilters)
                  InputChip(
                    avatar: Icon(category.icon, size: 16, color: category.color),
                    label: Text(category.label),
                    onDeleted: () {
                      setState(() => _categoryFilters.remove(category));
                    },
                  ),
              ],
            ),
          ),
        TxHeatmap(
          month: _month,
          counts: counts,
          canGoForward: _month.isBefore(nowMonth),
          selectedDay: _selectedDay,
          onPreviousMonth: () => _goMonth(-1),
          onNextMonth: () => _goMonth(1),
          onSelectDay: (day) => setState(() => _selectedDay = day),
        ),
        if (_selectedDay != null)
          Padding(
            padding: const EdgeInsets.only(bottom: 8),
            child: Align(
              alignment: Alignment.centerLeft,
              child: InputChip(
                label: Text(formatDate(_selectedDay!)),
                onDeleted: () => setState(() => _selectedDay = null),
              ),
            ),
          ),
        Padding(
          padding: const EdgeInsets.fromLTRB(0, 4, 0, 12),
          child: Row(
            children: [
              Expanded(
                child: _TotalsCard(
                  label: 'Money out',
                  value: formatMoney(moneyOut, currency),
                  color: colors.error,
                  icon: Icons.arrow_upward,
                ),
              ),
              const SizedBox(width: 10),
              Expanded(
                child: _TotalsCard(
                  label: 'Money in',
                  value: formatMoney(moneyIn, currency),
                  color: colors.primary,
                  icon: Icons.arrow_downward,
                ),
              ),
            ],
          ),
        ),
        if (_isSearching)
          Padding(
            padding: const EdgeInsets.only(bottom: 8),
            child: Text(
              _searchInMonthOnly
                  ? 'Searching in ${formatMonthYear(_month)}'
                  : 'Searching all transactions',
              style: theme.textTheme.labelMedium,
            ),
          ),
        if (filtered.isEmpty)
          Padding(
            padding: const EdgeInsets.symmetric(vertical: 24),
            child: Text(
              _isSearching
                  ? 'No transactions match this search.'
                  : _selectedDay != null
                      ? 'No transactions on this day.'
                      : 'No transactions this month.',
              textAlign: TextAlign.center,
              style: theme.textTheme.bodyMedium,
            ),
          )
        else
          for (var i = 0; i < filtered.length; i++) ...[
            if (i > 0)
              Divider(
                height: 1,
                color: colors.outlineVariant.withValues(alpha: 0.5),
              ),
            _CompactTransactionTile(
              tx: filtered[i],
              meta: metaController.metaFor(filtered[i]),
            ),
          ],
      ],
    );
  }
}

class _TotalsCard extends StatelessWidget {
  const _TotalsCard({
    required this.label,
    required this.value,
    required this.color,
    required this.icon,
  });

  final String label;
  final String value;
  final Color color;
  final IconData icon;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = theme.colorScheme;

    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 12),
      decoration: BoxDecoration(
        color: colors.surfaceContainerLow,
        borderRadius: BorderRadius.circular(14),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Icon(icon, size: 16, color: color),
              const SizedBox(width: 6),
              Text(label, style: theme.textTheme.labelMedium),
            ],
          ),
          const SizedBox(height: 6),
          Text(
            value,
            style: theme.textTheme.titleMedium?.copyWith(color: color),
          ),
        ],
      ),
    );
  }
}

class _CompactTransactionTile extends StatelessWidget {
  const _CompactTransactionTile({
    required this.tx,
    required this.meta,
  });

  final BankTransaction tx;
  final TxMeta meta;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = theme.colorScheme;
    final amountColor = tx.amount >= 0 ? colors.primary : colors.error;

    return InkWell(
      onTap: () {
        Navigator.of(context).push(
          MaterialPageRoute<void>(
            builder: (_) => TransactionDetailScreen(tx: tx),
          ),
        );
      },
      child: Padding(
        padding: const EdgeInsets.symmetric(vertical: 10),
        child: Row(
          children: [
            Container(
              width: 36,
              height: 36,
              decoration: BoxDecoration(
                color: meta.category.color.withValues(alpha: 0.14),
                borderRadius: BorderRadius.circular(10),
              ),
              child: Icon(
                meta.category.icon,
                size: 18,
                color: meta.category.color,
              ),
            ),
            const SizedBox(width: 12),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    tx.description,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: theme.textTheme.bodyLarge?.copyWith(
                      fontSize: 15,
                      height: 1.2,
                    ),
                  ),
                  const SizedBox(height: 2),
                  Text(
                    [
                      formatIsoDate(tx.date),
                      if (meta.hasCategory) meta.category.label,
                      if (meta.recurring) 'Recurring',
                      if (meta.hasNotes) 'Note',
                      if (tx.pending) 'Pending',
                    ].join(' · '),
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: theme.textTheme.labelMedium,
                  ),
                ],
              ),
            ),
            const SizedBox(width: 8),
            Text(
              formatMoney(tx.amount, tx.currency),
              style: theme.textTheme.titleSmall?.copyWith(
                color: amountColor,
                fontWeight: FontWeight.w600,
              ),
            ),
          ],
        ),
      ),
    );
  }
}