import 'dart:async';

/// Shared helpers for case-insensitive, trimmed, multi-field table search.
class TableSearch {
  TableSearch._();

  /// Trims leading/trailing whitespace. Does not alter casing.
  static String normalize(String? query) => query?.trim() ?? '';

  /// Trimmed + lowercased query for matching.
  static String normalizedQuery(String? query) => normalize(query).toLowerCase();

  /// Returns true when [query] is empty or any [values] contain the query.
  static bool matches(String? query, Iterable<Object?> values) {
    final q = normalizedQuery(query);
    if (q.isEmpty) return true;

    for (final value in values) {
      if (value == null) continue;
      final text = value.toString().trim().toLowerCase();
      if (text.isEmpty) continue;
      if (text.contains(q)) return true;
    }
    return false;
  }

  /// Filters [items] to those where any extracted field matches [query].
  static List<T> filter<T>(
    Iterable<T> items,
    String? query,
    Iterable<Object?> Function(T item) valuesOf,
  ) {
    final q = normalizedQuery(query);
    if (q.isEmpty) {
      return items is List<T> ? items : items.toList();
    }
    return items.where((item) => matches(q, valuesOf(item))).toList();
  }
}

/// Debounces search input so API-backed lists are not hit on every keystroke.
class SearchDebouncer {
  SearchDebouncer({this.duration = const Duration(milliseconds: 300)});

  final Duration duration;
  Timer? _timer;

  /// Runs [action] after [duration]. Empty queries run immediately.
  void run(String query, void Function(String normalized) action) {
    final normalized = TableSearch.normalize(query);
    _timer?.cancel();
    if (normalized.isEmpty) {
      action(normalized);
      return;
    }
    _timer = Timer(duration, () => action(normalized));
  }

  void dispose() {
    _timer?.cancel();
    _timer = null;
  }
}