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

import 'dart:async';

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/label_filter_dialog.dart';
import '../widgets/loading_view.dart';
import '../widgets/responsive_body.dart';
import '../widgets/skip_build_when_covered.dart';
import '../widgets/tx_heatmap.dart';
import 'transaction_detail_screen.dart';

class TransactionsScreen extends StatefulWidget {
  const TransactionsScreen({
    super.key,
    this.initialMonth,
    this.initialLabelIds = const {},
    this.initialSearchInMonthOnly,
    this.initialYear,
  });

  /// When set, opens on this calendar month instead of the current month.
  final DateTime? initialMonth;

  /// Pre-select these label filters (e.g. from overview history).
  final Set<String> initialLabelIds;

  /// When set, overrides the default "search in month" checkbox.
  final bool? initialSearchInMonthOnly;

  /// When set, label/search results are limited to this calendar year.
  final int? initialYear;

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

class _TransactionsScreenState extends State<TransactionsScreen> {
  static const _minLiveSearchChars = 3;
  static const _searchDebounce = Duration(milliseconds: 280);

  final _searchController = TextEditingController();
  late DateTime _month;
  DateTime? _selectedDay;
  late bool _searchInMonthOnly;
  late final Set<String> _labelFilters;
  int? _yearFilter;
  var _showCalendar = false;

  /// Query actually used for filtering (Enter, or live once ≥3 chars).
  String _activeQuery = '';
  Timer? _searchDebounceTimer;

  @override
  void initState() {
    super.initState();
    final initial = widget.initialMonth;
    final now = monthStart(DateTime.now());
    if (initial == null) {
      _month = now;
    } else {
      final start = monthStart(initial);
      _month = start.isAfter(now) ? now : start;
    }
    _labelFilters = Set<String>.of(widget.initialLabelIds);
    _searchInMonthOnly = widget.initialSearchInMonthOnly ?? false;
    _yearFilter = widget.initialYear;
  }

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

  bool get _isSearching =>
      _activeQuery.trim().isNotEmpty || _labelFilters.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);

  List<BankTransaction> _yearScoped(List<BankTransaction> all) {
    final year = _yearFilter;
    if (year == null) return all;
    return [
      for (final tx in all)
        if (_txDate(tx)?.year == year) tx,
    ];
  }

  void _onSearchChanged(String value) {
    final trimmed = value.trim();
    _searchDebounceTimer?.cancel();

    if (trimmed.length >= _minLiveSearchChars) {
      // TextField updates via the controller; only rebuild the list after debounce.
      _searchDebounceTimer = Timer(_searchDebounce, () {
        if (!mounted) return;
        if (_activeQuery == trimmed) return;
        setState(() => _activeQuery = trimmed);
      });
      return;
    }

    // Below threshold: no live search. Clear active text filter if needed.
    if (_activeQuery.isNotEmpty) {
      setState(() => _activeQuery = '');
    }
  }

  void _onSearchSubmitted(String value) {
    _searchDebounceTimer?.cancel();
    setState(() => _activeQuery = value.trim());
  }

  void _clearSearch() {
    _searchDebounceTimer?.cancel();
    _searchController.clear();
    setState(() => _activeQuery = '');
  }

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

    final result = await showLabelFilterDialog(
      context,
      available: available,
      initiallySelected: Set<String>.of(_labelFilters),
      title: 'Filter transactions',
      subtitle: 'Show transactions with any of these labels.',
      includeUncategorized: true,
    );
    if (result == null || !mounted) return;

    setState(() {
      _labelFilters
        ..clear()
        ..addAll(result);
    });
  }

  @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: Column(
        children: [
          if (bank.isLoading && bank.transactions.isNotEmpty)
            const LinearProgressIndicator(minHeight: 2),
          Expanded(
            child: RefreshIndicator(
              onRefresh: bank.refresh,
              child: ResponsiveBody(
                child: SkipBuildWhenCovered(
                  builder: (context) => _buildBody(context, bank),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }

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

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

    if (!bank.isLinked && txs.isEmpty) {
      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 && txs.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 (txs.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>[];
    final calendarScoped = <BankTransaction>[];
    final monthScoped = <BankTransaction>[];

    for (final tx in txs) {
      final date = _txDate(tx);
      if (date == null) continue;
      if (isSameMonth(date, _month)) {
        monthDates.add(dateOnly(date));
        monthScoped.add(tx);
        if (_selectedDay == null || isSameDay(date, _selectedDay!)) {
          calendarScoped.add(tx);
        }
      } else if (_selectedDay != null && isSameDay(date, _selectedDay!)) {
        calendarScoped.add(tx);
      }
    }
    final counts = txCountsByDay(monthDates);

    final searchPool = !_isSearching
        ? calendarScoped
        : _searchInMonthOnly
            ? monthScoped
            : _yearScoped(txs);

    // Text hits first (no label filter) so refine chips stay available while selecting.
    final textMatched = _activeQuery.trim().isEmpty
        ? const <BankTransaction>[]
        : metaController.search(searchPool, _activeQuery);

    final filtered = metaController.search(
      searchPool,
      _activeQuery,
      labelIds: _labelFilters,
    );

    final refineLabels = _activeQuery.trim().isEmpty
        ? const <TxLabel>[]
        : metaController.usedLabels(textMatched);
    final showUncategorizedRefine = _activeQuery.trim().isNotEmpty &&
        textMatched.any((tx) => !metaController.metaFor(tx).hasLabel);
    final refineChoices = <TxLabel>[
      if (showUncategorizedRefine &&
          !_labelFilters.contains(kUncategorizedFilterId))
        kUncategorizedFilterLabel,
      for (final label in refineLabels)
        if (!_labelFilters.contains(label.id)) label,
    ];

    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 ??
        (txs.isNotEmpty ? txs.first.currency : 'EUR');
    final labelById = {
      for (final label in metaController.allLabels) label.id: label,
    };

    return CustomScrollView(
      physics: const AlwaysScrollableScrollPhysics(),
      slivers: [
        if (bank.error != null && txs.isNotEmpty)
          SliverToBoxAdapter(
            child: Padding(
              padding: const EdgeInsets.only(top: 8, bottom: 4),
              child: Material(
                color: colors.errorContainer,
                borderRadius: BorderRadius.circular(10),
                child: Padding(
                  padding: const EdgeInsets.symmetric(
                    horizontal: 12,
                    vertical: 8,
                  ),
                  child: Text(
                    bank.error!,
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: colors.onErrorContainer,
                    ),
                  ),
                ),
              ),
            ),
          ),
        SliverToBoxAdapter(
          child: Padding(
            padding: const EdgeInsets.only(top: 8, bottom: 4),
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Expanded(
                  child: ValueListenableBuilder<TextEditingValue>(
                    valueListenable: _searchController,
                    builder: (context, value, _) {
                      final draft = value.text.trim();
                      final showHint = draft.isNotEmpty &&
                          draft.length < _minLiveSearchChars &&
                          draft != _activeQuery.trim();
                      return Column(
                        crossAxisAlignment: CrossAxisAlignment.stretch,
                        children: [
                          TextField(
                            controller: _searchController,
                            textInputAction: TextInputAction.search,
                            decoration: InputDecoration(
                              hintText:
                                  'Search (3+ chars, or press search)',
                              prefixIcon: const Icon(Icons.search),
                              suffixIcon: value.text.isNotEmpty
                                  ? IconButton(
                                      tooltip: 'Clear',
                                      onPressed: _clearSearch,
                                      icon: const Icon(Icons.clear),
                                    )
                                  : null,
                            ),
                            onChanged: _onSearchChanged,
                            onSubmitted: _onSearchSubmitted,
                          ),
                          if (showHint)
                            Padding(
                              padding: const EdgeInsets.only(top: 6),
                              child: Text(
                                'Press search to look up short terms',
                                style:
                                    theme.textTheme.labelMedium?.copyWith(
                                  color: colors.onSurfaceVariant,
                                ),
                              ),
                            ),
                        ],
                      );
                    },
                  ),
                ),
                const SizedBox(width: 2),
                IconButton(
                  tooltip: _labelFilters.isEmpty
                      ? 'Filter by label'
                      : 'Filter by label (${_labelFilters.length})',
                  onPressed: () => _pickLabels(
                    metaController.usedLabels(txs),
                  ),
                  style: IconButton.styleFrom(
                    backgroundColor: _labelFilters.isEmpty
                        ? null
                        : colors.secondaryContainer,
                  ),
                  icon: Badge(
                    isLabelVisible: _labelFilters.isNotEmpty,
                    smallSize: 6,
                    child: const Icon(Icons.filter_list),
                  ),
                ),
                IconButton(
                  tooltip: _showCalendar ? 'Hide calendar' : 'Show calendar',
                  onPressed: () {
                    setState(() {
                      _showCalendar = !_showCalendar;
                      if (!_showCalendar) _selectedDay = null;
                    });
                  },
                  style: IconButton.styleFrom(
                    backgroundColor: _showCalendar
                        ? colors.secondaryContainer
                        : null,
                  ),
                  icon: Icon(
                    _showCalendar
                        ? Icons.calendar_month
                        : Icons.calendar_month_outlined,
                  ),
                ),
                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 (_showCalendar) ...[
          SliverToBoxAdapter(
            child: 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)
            SliverToBoxAdapter(
              child: Padding(
                padding: const EdgeInsets.only(bottom: 8),
                child: Align(
                  alignment: Alignment.centerLeft,
                  child: InputChip(
                    label: Text(formatDate(_selectedDay!)),
                    onDeleted: () => setState(() => _selectedDay = null),
                  ),
                ),
              ),
            ),
        ] else
          SliverToBoxAdapter(
            child: Padding(
              padding: const EdgeInsets.fromLTRB(0, 4, 0, 8),
              child: Row(
                children: [
                  IconButton(
                    tooltip: 'Previous month',
                    onPressed: () => _goMonth(-1),
                    icon: const Icon(Icons.chevron_left),
                  ),
                  Expanded(
                    child: Text(
                      formatMonthYear(_month),
                      textAlign: TextAlign.center,
                      style: theme.textTheme.titleMedium,
                    ),
                  ),
                  IconButton(
                    tooltip: 'Next month',
                    onPressed:
                        _month.isBefore(nowMonth) ? () => _goMonth(1) : null,
                    icon: const Icon(Icons.chevron_right),
                  ),
                ],
              ),
            ),
          ),
        SliverToBoxAdapter(
          child: 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 || _labelFilters.isNotEmpty)
          SliverToBoxAdapter(
            child: Padding(
              padding: const EdgeInsets.only(bottom: 8),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  if (_isSearching)
                    Text(
                      _yearFilter != null
                          ? 'Filtered to $_yearFilter'
                          : _searchInMonthOnly
                              ? 'Searching in ${formatMonthYear(_month)}'
                              : 'Searching all transactions',
                      style: theme.textTheme.labelMedium,
                    ),
                  if (_labelFilters.isNotEmpty) ...[
                    if (_isSearching) const SizedBox(height: 8),
                    Wrap(
                      spacing: 6,
                      runSpacing: 6,
                      children: [
                        for (final id in _labelFilters)
                          if (id == kUncategorizedFilterId)
                            InputChip(
                              visualDensity: VisualDensity.compact,
                              avatar: Icon(
                                kUncategorizedFilterLabel.icon,
                                size: 14,
                                color: kUncategorizedFilterLabel.color,
                              ),
                              label: const Text('Uncategorized'),
                              onDeleted: () {
                                setState(
                                  () => _labelFilters
                                      .remove(kUncategorizedFilterId),
                                );
                              },
                            )
                          else if (labelById[id] != null)
                            InputChip(
                              visualDensity: VisualDensity.compact,
                              avatar: Icon(
                                labelById[id]!.icon,
                                size: 14,
                                color: labelById[id]!.color,
                              ),
                              label: Text(labelById[id]!.name),
                              onDeleted: () {
                                setState(() => _labelFilters.remove(id));
                              },
                            ),
                      ],
                    ),
                  ],
                  if (refineChoices.isNotEmpty) ...[
                    const SizedBox(height: 8),
                    Text(
                      'Refine by label',
                      style: theme.textTheme.labelSmall?.copyWith(
                        color: colors.onSurfaceVariant,
                      ),
                    ),
                    const SizedBox(height: 6),
                    Wrap(
                      spacing: 6,
                      runSpacing: 6,
                      children: [
                        for (final label in refineChoices)
                          FilterChip(
                            visualDensity: VisualDensity.compact,
                            materialTapTargetSize:
                                MaterialTapTargetSize.shrinkWrap,
                            avatar: Icon(
                              label.icon,
                              size: 14,
                              color: label.color,
                            ),
                            label: Text(label.name),
                            selected: false,
                            onSelected: (_) {
                              setState(() => _labelFilters.add(label.id));
                            },
                          ),
                      ],
                    ),
                  ],
                ],
              ),
            ),
          ),
        SliverToBoxAdapter(
          child: Padding(
            padding: const EdgeInsets.only(bottom: 8),
            child: Text(
              filtered.length == 1
                  ? '1 transaction'
                  : '${filtered.length} transactions',
              style: theme.textTheme.titleSmall?.copyWith(
                color: colors.onSurfaceVariant,
              ),
            ),
          ),
        ),
        if (filtered.isEmpty)
          SliverToBoxAdapter(
            child: 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
          SliverList(
            delegate: SliverChildBuilderDelegate(
              (context, index) {
                final tx = filtered[index];
                final meta = metaController.metaFor(tx);
                return Column(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    if (index > 0)
                      Divider(
                        height: 1,
                        color: colors.outlineVariant.withValues(alpha: 0.5),
                      ),
                    _CompactTransactionTile(
                      tx: tx,
                      meta: meta,
                      labels: metaController.leafLabelsFor(meta),
                    ),
                  ],
                );
              },
              childCount: filtered.length,
              addAutomaticKeepAlives: false,
            ),
          ),
        const SliverToBoxAdapter(child: SizedBox(height: 32)),
      ],
    );
  }
}

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,
    this.labels = const [],
  });

  final BankTransaction tx;
  final TxMeta meta;
  final List<TxLabel> labels;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = theme.colorScheme;
    final amountColor = tx.amount >= 0 ? colors.primary : colors.error;
    final primary = labels.isEmpty ? null : labels.first;
    final iconColor = primary?.color ?? colors.outline;
    final iconData = primary?.icon ?? Icons.receipt_long_outlined;

    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: iconColor.withValues(alpha: 0.14),
                borderRadius: BorderRadius.circular(10),
              ),
              child: Icon(
                iconData,
                size: 18,
                color: iconColor,
              ),
            ),
            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 (labels.isNotEmpty)
                        labels.map((l) => l.name).join(', '),
                      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,
              ),
            ),
          ],
        ),
      ),
    );
  }
}