/// Defensive JSON helpers for the Subsonic protocol.
///
/// Subsonic servers are inconsistent (Ratune handles the same quirks in
/// `ratune-subsonic/src/models.rs` via `OneOrMany` / `deserialize_flexible_id`):
///   * a field that is sometimes a single object and sometimes an array
///   * IDs that are sometimes strings and sometimes integers
/// Every accessor below tolerates nulls and mixed types rather than throwing.
library;

/// Coerce a value that may be a single object, a list, or null into a list of
/// `T`, applying [fromJson] to each map element.
List<T> oneOrMany<T>(
  dynamic value,
  T Function(Map<String, dynamic>) fromJson,
) {
  if (value == null) return const [];
  if (value is List) {
    return value
        .whereType<Map>()
        .map((e) => fromJson(e.cast<String, dynamic>()))
        .toList();
  }
  if (value is Map) {
    return [fromJson(value.cast<String, dynamic>())];
  }
  return const [];
}

/// Read a string that the server might encode as an int (e.g. IDs).
String? asString(dynamic value) {
  if (value == null) return null;
  if (value is String) return value;
  return value.toString();
}

/// Read an int from a value that might be an int, num, or numeric string.
int? asInt(dynamic value) {
  if (value == null) return null;
  if (value is int) return value;
  if (value is num) return value.toInt();
  if (value is String) return int.tryParse(value);
  return null;
}

/// Read a double from an int/num/numeric-string.
double? asDouble(dynamic value) {
  if (value == null) return null;
  if (value is double) return value;
  if (value is num) return value.toDouble();
  if (value is String) return double.tryParse(value);
  return null;
}

/// Read a bool that might arrive as a bool or the string "true"/"false".
bool asBool(dynamic value, {bool orElse = false}) {
  if (value is bool) return value;
  if (value is String) return value.toLowerCase() == 'true';
  return orElse;
}