testsAndMisc-archive/billsplit/lib/ui/receipt_screen.dart

import 'package:billsplit/domain/models.dart';
import 'package:billsplit/domain/split_engine.dart';
import 'package:billsplit/domain/xlsx_export.dart';
import 'package:billsplit/state/app_state.dart';
import 'package:billsplit/ui/assignment_sheet.dart';
import 'package:billsplit/ui/item_edit.dart';
import 'package:file_picker/file_picker.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

/// One receipt: item list with assignments, totals, participants, export.
class ReceiptScreen extends StatefulWidget {
  /// Creates the screen for the receipt with [receiptId].
  const ReceiptScreen({required this.receiptId, super.key});

  /// Id of the receipt to show; resolved against [AppState.receipts].
  final String receiptId;

  @override
  State<ReceiptScreen> createState() => _ReceiptScreenState();
}

class _ReceiptScreenState extends State<ReceiptScreen> {
  @override
  Widget build(BuildContext context) {
    final state = context.watch<AppState>();
    final receipt =
        state.receipts.where((r) => r.id == widget.receiptId).firstOrNull;
    if (receipt == null) {
      return const Scaffold(body: Center(child: Text('Receipt deleted.')));
    }
    final split = computeSplit(receipt, state.people, state.groups);
    final wide = MediaQuery.of(context).size.width > 800;

    final itemsList = _ItemsList(receipt: receipt, split: split);
    final totals = _TotalsView(receipt: receipt, split: split);

    return DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          title: Text(receipt.title, overflow: TextOverflow.ellipsis),
          actions: [
            IconButton(
              tooltip: 'Participants',
              icon: const Icon(Icons.group),
              onPressed: () => _editParticipants(context, state, receipt),
            ),
            IconButton(
              tooltip: 'Export .xlsx',
              icon: const Icon(Icons.table_view),
              onPressed: () => _export(context, state, receipt),
            ),
          ],
          bottom: wide
              ? null
              : const TabBar(
                  tabs: [
                    Tab(text: 'Items'),
                    Tab(text: 'Totals'),
                  ],
                ),
        ),
        floatingActionButton: FloatingActionButton(
          tooltip: 'Add item',
          child: const Icon(Icons.add),
          onPressed: () => showItemEditDialog(context, state, receipt, null),
        ),
        body: wide
            ? Row(
                children: [
                  Expanded(flex: 3, child: itemsList),
                  const VerticalDivider(width: 1),
                  Expanded(flex: 2, child: totals),
                ],
              )
            : TabBarView(children: [itemsList, totals]),
      ),
    );
  }

  Future<void> _editParticipants(
    BuildContext context,
    AppState state,
    Receipt receipt,
  ) async {
    if (state.people.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text('Add people first (People & groups screen).'),
        ),
      );
      return;
    }
    await showModalBottomSheet<void>(
      context: context,
      builder: (c) => StatefulBuilder(
        builder: (c, setSheet) => SafeArea(
          child: ListView(
            shrinkWrap: true,
            children: [
              Padding(
                padding: const EdgeInsets.all(16),
                child: Text(
                  'Who is on this receipt?',
                  style: Theme.of(c).textTheme.titleMedium,
                ),
              ),
              for (final p in state.people)
                CheckboxListTile(
                  title: Text(p.name),
                  subtitle: p.drinks ? null : const Text('non-drinker'),
                  value: receipt.participantIds.contains(p.id),
                  onChanged: (v) {
                    state.mutate(() {
                      if (v == true) {
                        receipt.participantIds.add(p.id);
                      } else {
                        receipt.participantIds.remove(p.id);
                      }
                    });
                    setSheet(() {});
                  },
                ),
            ],
          ),
        ),
      ),
    );
  }

  Future<void> _export(
    BuildContext context,
    AppState state,
    Receipt receipt,
  ) async {
    final messenger = ScaffoldMessenger.of(context);
    if (receipt.participantIds.isEmpty) {
      messenger.showSnackBar(
        const SnackBar(content: Text('Add participants before exporting.')),
      );
      return;
    }
    try {
      final bytes = Uint8List.fromList(
        exportXlsx(
          receipt: receipt,
          roster: state.people,
          groups: state.groups,
        ),
      );
      final safe = receipt.title.replaceAll(
        RegExp(r'[^\w\d ąćęłńóśżźĄĆĘŁŃÓŚŻŹ-]'),
        '_',
      );
      final path = await FilePicker.saveFile(
        dialogTitle: 'Save split as .xlsx',
        fileName: '$safe split.xlsx',
        type: FileType.custom,
        allowedExtensions: ['xlsx'],
        bytes: bytes,
      );
      if (path != null) {
        messenger.showSnackBar(
          SnackBar(content: Text('Saved: ${path.split('/').last}')),
        );
      }
    } on Exception catch (e) {
      messenger.showSnackBar(SnackBar(content: Text('Export failed: $e')));
    }
  }
}

class _ItemsList extends StatelessWidget {
  const _ItemsList({required this.receipt, required this.split});
  final Receipt receipt;
  final SplitResult split;

  @override
  Widget build(BuildContext context) {
    final state = context.read<AppState>();
    if (receipt.items.isEmpty) {
      return const Center(child: Text('No items — add with +.'));
    }
    return ListView.builder(
      padding: const EdgeInsets.only(bottom: 96),
      itemCount: receipt.items.length,
      itemBuilder: (context, i) {
        final item = receipt.items[i];
        final people =
            resolveParticipants(item, receipt, state.people, state.groups);
        final unassigned = people.isEmpty;
        return ListTile(
          dense: true,
          leading: _CategoryDot(category: item.category),
          title: Text(item.name),
          subtitle: Text(
            _assignmentLabel(item, people.length, state),
            style: TextStyle(
              color: unassigned ? Colors.red : null,
              fontWeight: unassigned ? FontWeight.bold : null,
            ),
          ),
          trailing: Text(formatPln(item.totalGr)),
          onTap: () => showAssignmentSheet(context, state, receipt, item),
          onLongPress: () => showItemEditDialog(context, state, receipt, item),
        );
      },
    );
  }

  String _assignmentLabel(Item item, int n, AppState state) {
    switch (item.assignment.mode) {
      case AssignMode.everyone:
        return 'Everyone ($n)';
      case AssignMode.drinkers:
        return 'Drinkers only ($n)';
      case AssignMode.nonDrinkers:
        return 'Non-drinkers ($n)';
      case AssignMode.group:
        final g = state.groups
            .where((g) => g.id == item.assignment.groupId)
            .firstOrNull;
        return 'Group: ${g?.name ?? '?'} ($n)';
      case AssignMode.custom:
        return n == 0 ? 'UNASSIGNED — tap to fix' : 'Selected people ($n)';
    }
  }
}

class _CategoryDot extends StatelessWidget {
  const _CategoryDot({required this.category});
  final String category;

  @override
  Widget build(BuildContext context) {
    final color = switch (category) {
      Categories.alcohol => Colors.deepOrange,
      Categories.mixer => Colors.amber,
      Categories.deposit => Colors.blueGrey,
      _ => Colors.teal,
    };
    return CircleAvatar(radius: 6, backgroundColor: color);
  }
}

class _TotalsView extends StatelessWidget {
  const _TotalsView({required this.receipt, required this.split});
  final Receipt receipt;
  final SplitResult split;

  @override
  Widget build(BuildContext context) {
    final state = context.read<AppState>();
    final people = receiptParticipants(receipt, state.people)
      ..sort((a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()));
    final itemsTotal = receipt.itemsTotalGr;
    final assigned = split.assignedTotalGr;
    final paid = receipt.paidTotalGr;

    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        if (split.unassigned.isNotEmpty)
          Card(
            color: Colors.red.shade50,
            child: Padding(
              padding: const EdgeInsets.all(12),
              child: Text(
                '${split.unassigned.length} item(s) have nobody assigned and '
                'are excluded from totals:\n'
                '${split.unassigned.map((i) => '· ${i.name}').join('\n')}',
                style: const TextStyle(color: Colors.red),
              ),
            ),
          ),
        for (final p in people)
          _PersonRow(person: p, total: split.perPerson[p.id]),
        const Divider(height: 32),
        _kv(context, 'Items total', formatPln(itemsTotal), bold: true),
        _kv(
          context,
          'Assigned to people',
          formatPln(assigned),
          warn: assigned != itemsTotal,
        ),
        if (paid != null)
          _kv(
            context,
            'Paid (receipt)',
            formatPln(paid),
            warn: paid != itemsTotal,
          ),
        const SizedBox(height: 8),
        Text(
          'Splits are grosz-exact: shares always add up to the item total, '
          'so no fractional grosze are lost.',
          style: Theme.of(context).textTheme.bodySmall,
        ),
      ],
    );
  }

  Widget _kv(
    BuildContext context,
    String k,
    String v, {
    bool bold = false,
    bool warn = false,
  }) {
    final style = TextStyle(
      fontWeight: bold || warn ? FontWeight.bold : null,
      color: warn ? Colors.red : null,
    );
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 2),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [Text(k, style: style), Text(v, style: style)],
      ),
    );
  }
}

class _PersonRow extends StatelessWidget {
  const _PersonRow({required this.person, required this.total});
  final Person person;
  final PersonTotal? total;

  @override
  Widget build(BuildContext context) {
    final t = total;
    return ListTile(
      contentPadding: EdgeInsets.zero,
      leading: CircleAvatar(
        child: Text(
          person.name.isEmpty ? '?' : person.name.substring(0, 1).toUpperCase(),
        ),
      ),
      title: Text(person.name),
      subtitle: t == null || t.alcoholGr == 0
          ? null
          : Text(
              'alcohol ${formatPln(t.alcoholGr)} · rest ${formatPln(t.restGr)}',
            ),
      trailing: Text(
        formatPln(t?.totalGr ?? 0),
        style: Theme.of(context).textTheme.titleMedium,
      ),
    );
  }
}

extension<T> on Iterable<T> {
  T? get firstOrNull => isEmpty ? null : first;
}