/// Dialog to refine “apply to similar” matching with a live match list.
library;

import 'package:flutter/material.dart';

import '../models/bank.dart';
import '../models/transaction_meta.dart';
import '../utils/app_theme.dart';
import '../utils/helpers.dart';

class _RegexExample {
  const _RegexExample({required this.label, required this.pattern});
  final String label;
  final String pattern;
}

List<_RegexExample> _regexExamplesFor(BankTransaction tx) {
  final stem = defaultSimilarPattern(tx.description);
  final escaped = RegExp.escape(stem);
  return [
    _RegexExample(
      label: 'Contains stem (flexible spaces)',
      pattern: '/${escaped.replaceAll(r'\ ', r'\s+')}/',
    ),
    _RegexExample(
      label: 'Starts with stem',
      pattern: '/^$escaped/',
    ),
    _RegexExample(
      label: 'Whole description is stem',
      pattern: '/^$escaped\$/',
    ),
    const _RegexExample(
      label: 'Digits / reference',
      pattern: r'/\d{4,}/',
    ),
    _RegexExample(
      label: 'Stem as whole word',
      pattern: '/\\b$escaped\\b/',
    ),
  ];
}

Future<SimilarMatchCriteria?> showSimilarMatchDialog(
  BuildContext context, {
  required BankTransaction prototype,
  required List<BankTransaction> all,
  required SimilarMatchCriteria initial,
}) {
  return showDialog<SimilarMatchCriteria>(
    context: context,
    builder: (dialogContext) {
      return _SimilarMatchDialog(
        prototype: prototype,
        all: all,
        initial: initial,
      );
    },
  );
}

class _SimilarMatchDialog extends StatefulWidget {
  const _SimilarMatchDialog({
    required this.prototype,
    required this.all,
    required this.initial,
  });

  final BankTransaction prototype;
  final List<BankTransaction> all;
  final SimilarMatchCriteria initial;

  @override
  State<_SimilarMatchDialog> createState() => _SimilarMatchDialogState();
}

class _SimilarMatchDialogState extends State<_SimilarMatchDialog> {
  late final TextEditingController _containsController;
  late TxFlowFilter _flow;

  @override
  void initState() {
    super.initState();
    _containsController = TextEditingController(text: widget.initial.pattern);
    _flow = widget.initial.flow;
  }

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

  SimilarMatchCriteria get _criteria => SimilarMatchCriteria(
        pattern: _containsController.text.trim(),
        flow: _flow,
      );

  List<BankTransaction> get _matches {
    final criteria = _criteria;
    if (criteria.pattern.isEmpty) return const [];
    return [
      for (final tx in widget.all)
        if (txMatchesSimilarCriteria(tx, criteria)) tx,
    ];
  }

  void _showRegexExamples() {
    final examples = _regexExamplesFor(widget.prototype);
    showModalBottomSheet<void>(
      context: context,
      showDragHandle: true,
      builder: (sheetContext) {
        return SafeArea(
          child: ListView(
            shrinkWrap: true,
            children: [
              Padding(
                padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
                child: Text(
                  'Regex examples',
                  style: Theme.of(sheetContext).textTheme.titleMedium,
                ),
              ),
              for (final example in examples)
                ListTile(
                  title: Text(example.label),
                  subtitle: Text(
                    example.pattern,
                    maxLines: 2,
                    overflow: TextOverflow.ellipsis,
                  ),
                  onTap: () {
                    Navigator.pop(sheetContext);
                    setState(() => _containsController.text = example.pattern);
                  },
                ),
            ],
          ),
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colors = theme.colorScheme;
    final matches = _matches;
    final maxListHeight = MediaQuery.sizeOf(context).height * 0.35;

    return AlertDialog(
      title: const Text('Match similar'),
      content: SizedBox(
        width: double.maxFinite,
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            TextField(
              controller: _containsController,
              textInputAction: TextInputAction.done,
              decoration: InputDecoration(
                labelText: 'Name contains',
                hintText: 'plain text or /regex/',
                helperText: 'Plain text = contains. Wrap with /…/ for regex.',
                helperMaxLines: 2,
                suffixIcon: IconButton(
                  tooltip: 'Regex examples',
                  onPressed: _showRegexExamples,
                  icon: const Icon(Icons.data_object_outlined),
                ),
              ),
              onChanged: (_) => setState(() {}),
            ),
            const SizedBox(height: 12),
            Text(
              'Income / expense',
              style: theme.textTheme.titleSmall,
            ),
            const SizedBox(height: 8),
            SegmentedButton<TxFlowFilter>(
              segments: const [
                ButtonSegment(
                  value: TxFlowFilter.all,
                  label: Text('All'),
                ),
                ButtonSegment(
                  value: TxFlowFilter.income,
                  label: Text('In'),
                  icon: Icon(Icons.south_west, size: 16),
                ),
                ButtonSegment(
                  value: TxFlowFilter.expense,
                  label: Text('Out'),
                  icon: Icon(Icons.north_east, size: 16),
                ),
              ],
              selected: {_flow},
              onSelectionChanged: (selected) {
                setState(() => _flow = selected.first);
              },
            ),
            const SizedBox(height: 12),
            Text(
              matches.isEmpty
                  ? 'No matches'
                  : '${matches.length} matching transaction'
                      '${matches.length == 1 ? '' : 's'}',
              style: theme.textTheme.titleSmall?.copyWith(
                color: colors.onSurface,
              ),
            ),
            const SizedBox(height: 6),
            ConstrainedBox(
              constraints: BoxConstraints(maxHeight: maxListHeight),
              child: DecoratedBox(
                decoration: BoxDecoration(
                  color: colors.surfaceContainerHighest,
                  borderRadius: BorderRadius.circular(12),
                  border: Border.all(
                    color: colors.outlineVariant.withValues(alpha: 0.8),
                  ),
                ),
                child: matches.isEmpty
                    ? Padding(
                        padding: const EdgeInsets.all(16),
                        child: Text(
                          'Adjust the pattern to see matches.',
                          style: theme.textTheme.bodyMedium?.copyWith(
                            color: colors.onSurfaceVariant,
                          ),
                        ),
                      )
                    : ListView.separated(
                        shrinkWrap: true,
                        padding: const EdgeInsets.symmetric(vertical: 4),
                        itemCount: matches.length,
                        separatorBuilder: (_, _) => Divider(
                          height: 1,
                          indent: 12,
                          color:
                              colors.outlineVariant.withValues(alpha: 0.45),
                        ),
                        itemBuilder: (context, index) {
                          final tx = matches[index];
                          final isPrototype = tx.id == widget.prototype.id;
                          return ListTile(
                            dense: true,
                            title: Text(
                              tx.description,
                              maxLines: 1,
                              overflow: TextOverflow.ellipsis,
                            ),
                            subtitle: Text(formatIsoDate(tx.date)),
                            trailing: Text(
                              formatMoney(tx.amount, tx.currency),
                              style: theme.textTheme.bodyMedium?.copyWith(
                                color: tx.amount >= 0
                                    ? AppTheme.accent
                                    : AppTheme.expense,
                                fontWeight:
                                    isPrototype ? FontWeight.w700 : null,
                              ),
                            ),
                          );
                        },
                      ),
              ),
            ),
          ],
        ),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: const Text('Cancel'),
        ),
        FilledButton(
          onPressed: _criteria.pattern.isEmpty
              ? null
              : () => Navigator.pop(context, _criteria),
          child: const Text('Apply'),
        ),
      ],
    );
  }
}