added categories, import export, settings

lib/utils/categories.dart

@@ -0,0 +1,29 @@
+/// Grocery categories a product can be assigned to.
+library;
+
+const List<String> kDefaultCategories = [
+  'Fruit & vegetables',
+  'Dairy & eggs',
+  'Meat & fish',
+  'Bread & bakery',
+  'Pantry',
+  'Drinks',
+  'Frozen',
+  'Snacks',
+  'Household',
+  'Personal care',
+];
+
+List<String> mergeCategories(Iterable<String> used) {
+  final seen = <String>{};
+  final result = <String>[];
+  for (final name in [...kDefaultCategories, ...used]) {
+    final trimmed = name.trim();
+    if (trimmed.isEmpty) continue;
+    final key = trimmed.toLowerCase();
+    if (seen.contains(key)) continue;
+    seen.add(key);
+    result.add(trimmed);
+  }
+  return result;
+}

lib/utils/dates.dart

@@ -0,0 +1,20 @@
+/// Date formatting for shop log and product history.
+library;
+
+const _months = [
+  'Jan',
+  'Feb',
+  'Mar',
+  'Apr',
+  'May',
+  'Jun',
+  'Jul',
+  'Aug',
+  'Sep',
+  'Oct',
+  'Nov',
+  'Dec',
+];
+
+String formatDate(DateTime date) =>
+    '${date.day} ${_months[date.month - 1]} ${date.year}';

lib/utils/fuzzy.dart

@@ -0,0 +1,40 @@
+/// Lightweight fuzzy matching for product search.
+library;
+
+String _normalize(String value) =>
+    value.trim().toLowerCase().replaceAll(RegExp(r'\s+'), ' ');
+
+/// True when [query] fuzzily matches [text].
+bool fuzzyMatch(String query, String text) {
+  final q = _normalize(query);
+  if (q.isEmpty) return true;
+  final t = _normalize(text);
+  if (t.contains(q)) return true;
+
+  for (final word in q.split(' ')) {
+    if (word.isEmpty) continue;
+    if (!t.contains(word) && !_subsequence(word, t)) return false;
+  }
+  if (q.contains(' ')) return true;
+  return _subsequence(q, t);
+}
+
+/// Higher is better. Null when [query] does not match.
+int? fuzzyScore(String query, String text) {
+  final q = _normalize(query);
+  if (q.isEmpty) return 0;
+  final t = _normalize(text);
+  if (t == q) return 1000;
+  if (t.startsWith(q)) return 800;
+  if (t.contains(q)) return 600 - t.indexOf(q);
+  if (!fuzzyMatch(q, t)) return null;
+  return 200 - (t.length - q.length).abs().clamp(0, 150);
+}
+
+bool _subsequence(String query, String text) {
+  var i = 0;
+  for (var c = 0; c < text.length && i < query.length; c++) {
+    if (text.codeUnitAt(c) == query.codeUnitAt(i)) i++;
+  }
+  return i == query.length;
+}

lib/utils/supermarkets.dart

@@ -0,0 +1,99 @@
+/// Known Dutch supermarket names, default colors, and OCR detection.
+library;
+
+import '../models/supermarket.dart';
+
+const String kOtherSupermarket = 'Other';
+
+final List<Supermarket> kDefaultSupermarkets = [
+  const Supermarket(name: 'Albert Heijn', colorValue: 0xFF00A0E2, sortOrder: 0),
+  const Supermarket(name: 'Jumbo', colorValue: 0xFFEEC21B, sortOrder: 1),
+  const Supermarket(name: 'Lidl', colorValue: 0xFF0050AA, sortOrder: 2),
+  const Supermarket(name: 'Aldi', colorValue: 0xFF00205B, sortOrder: 3),
+  const Supermarket(name: 'Plus', colorValue: 0xFF6EC31E, sortOrder: 4),
+  const Supermarket(name: 'Dirk', colorValue: 0xFFE30613, sortOrder: 5),
+  const Supermarket(name: 'Coop', colorValue: 0xFFE30613, sortOrder: 6),
+  const Supermarket(name: 'SPAR', colorValue: 0xFF009640, sortOrder: 7),
+  const Supermarket(name: 'Nettorama', colorValue: 0xFFE87722, sortOrder: 8),
+  const Supermarket(name: 'Hoogvliet', colorValue: 0xFFD32F2F, sortOrder: 9),
+  const Supermarket(name: 'Picnic', colorValue: 0xFFE31C5F, sortOrder: 10),
+  const Supermarket(name: kOtherSupermarket, colorValue: 0xFF78909C, sortOrder: 11),
+];
+
+const Map<String, List<String>> kSupermarketAliases = {
+  'Albert Heijn': ['ALBERT HEIJN', 'AH TO GO', 'AH XL'],
+  'Jumbo': ['JUMBO'],
+  'Lidl': ['LIDL'],
+  'Aldi': ['ALDI'],
+  'Plus': ['PLUS'],
+  'Dirk': ['DIRK'],
+  'Coop': ['COOP'],
+  'SPAR': ['SPAR'],
+  'Nettorama': ['NETTORAMA'],
+  'Hoogvliet': ['HOOGVLIET'],
+  'Picnic': ['PICNIC'],
+};
+
+/// Names used before settings were user-editable.
+const List<String> kSupermarkets = [
+  'Albert Heijn',
+  'Jumbo',
+  'Lidl',
+  'Aldi',
+  'Plus',
+  'Dirk',
+  'Coop',
+  'SPAR',
+  'Nettorama',
+  'Hoogvliet',
+  'Picnic',
+  'Other',
+];
+
+/// Returns a supermarket name if it appears in [rawText].
+String? detectSupermarket(
+  String rawText, {
+  Iterable<String> names = const [],
+}) {
+  final upper = rawText.toUpperCase();
+  final extra = names
+      .map((name) => name.trim())
+      .where((name) => name.isNotEmpty && name != kOtherSupermarket)
+      .toList()
+    ..sort((a, b) => b.length.compareTo(a.length));
+
+  for (final name in extra) {
+    if (RegExp('\\b${RegExp.escape(name)}\\b', caseSensitive: false)
+        .hasMatch(rawText)) {
+      return name;
+    }
+  }
+
+  for (final entry in kSupermarketAliases.entries) {
+    for (final alias in entry.value) {
+      if (RegExp('\\b${RegExp.escape(alias)}\\b').hasMatch(upper)) {
+        return _canonicalName(entry.key, extra);
+      }
+    }
+  }
+
+  if (RegExp(r'\bAH\b').hasMatch(upper)) {
+    return _canonicalName('Albert Heijn', extra);
+  }
+  return null;
+}
+
+String _canonicalName(String fallback, List<String> names) {
+  for (final name in names) {
+    if (name.toUpperCase() == fallback.toUpperCase()) return name;
+  }
+  return fallback;
+}
+
+Supermarket? supermarketByName(Iterable<Supermarket> stores, String? name) {
+  if (name == null || name.isEmpty) return null;
+  for (final store in stores) {
+    if (store.name.toLowerCase() == name.toLowerCase()) return store;
+  }
+  return null;
+}