import 'package:json_annotation/json_annotation.dart';

/// Decodes server lists element by element so one entry the model cannot map
/// (a field the server dropped, an enum value it added) is skipped and
/// recorded instead of failing the whole response and with it the screen.
///
/// Skipped entries are collected per isolate; the API layer drains them with
/// [drainDecodeWarnings] and reports them, so a drift in the server's format
/// still reaches us without taking the feature down for the user.
final List<String> _warnings = [];

List<T> decodeListLenient<T>(
  Object? raw,
  T Function(Map<String, dynamic>) fromJson, {
  required String what,
}) {
  final items = <T>[];
  if (raw is! List<dynamic>) {
    throw FormatException(
      'expected a list of ${what}s, got ${raw.runtimeType}',
    );
  }
  for (final entry in raw) {
    try {
      items.add(fromJson(entry as Map<String, dynamic>));
    } on CheckedFromJsonException catch (e) {
      _warnings.add('$what: $e');
    } on TypeError catch (e) {
      _warnings.add('$what: $e');
    }
  }
  return items;
}

Set<T> decodeSetLenient<T>(
  Object? raw,
  T Function(Map<String, dynamic>) fromJson, {
  required String what,
}) => decodeListLenient(raw, fromJson, what: what).toSet();

/// Returns and clears the entries skipped since the last call.
List<String> drainDecodeWarnings() {
  final out = List<String>.of(_warnings);
  _warnings.clear();
  return out;
}