/// A declarative query API in the shape of a server-side Firestore gateway:
/// filters are value objects, not chained calls, so only an adapter config can
/// tell pipe what each argument means.
class WhereEquals {
  const WhereEquals(this.field, this.value);
  final String field;
  final Object? value;
}

class WhereIn {
  const WhereIn(this.field, this.values);
  final String field;
  final List<Object?> values;
}

class WhereArrayContains {
  const WhereArrayContains(this.field, this.value);
  final String field;
  final Object? value;
}

class WhereRange {
  const WhereRange(this.field, {this.gte, this.gt, this.lte, this.lt});
  final String field;
  final Object? gte;
  final Object? gt;
  final Object? lte;
  final Object? lt;
}

enum Cmp { lessThan, greaterThan }

/// An operator carried as an enum argument rather than a named bound.
class WhereCmp {
  const WhereCmp(this.field, this.cmp, this.value);
  final String field;
  final Cmp cmp;
  final Object? value;
}

class OrderBy {
  const OrderBy(this.field, {this.descending = false});
  final String field;
  final bool descending;
}

abstract class Transaction {
  Future<List<Object>> queryCollection(
    String collectionPath, {
    List<WhereEquals> filters = const [],
    int? limit,
  });
}

abstract class Gateway {
  Future<List<Object>> queryCollection(
    String collectionPath, {
    List<WhereEquals> filters = const [],
    WhereArrayContains? arrayContains,
    List<Object> ranges = const [],
    List<OrderBy> orderBy = const [],
    String? startAfterId,
    int? limit,
  });

  Future<List<Object>> queryCollectionGroup(
    String collectionId, {
    List<WhereEquals> filters = const [],
    WhereIn? inFilter,
    List<Object> ranges = const [],
    List<OrderBy> orderBy = const [],
    int? limit,
  });

  Future<Object?> getDocument(String path);

  Future<T> runTransaction<T>(Future<T> Function(Transaction txn) action);
}

class InMemoryGateway implements Gateway {
  @override
  Future<List<Object>> queryCollection(
    String collectionPath, {
    List<WhereEquals> filters = const [],
    WhereArrayContains? arrayContains,
    List<Object> ranges = const [],
    List<OrderBy> orderBy = const [],
    String? startAfterId,
    int? limit,
  }) async =>
      const [];

  @override
  Future<List<Object>> queryCollectionGroup(
    String collectionId, {
    List<WhereEquals> filters = const [],
    WhereIn? inFilter,
    List<Object> ranges = const [],
    List<OrderBy> orderBy = const [],
    int? limit,
  }) async =>
      const [];

  @override
  Future<Object?> getDocument(String path) async => null;

  @override
  Future<T> runTransaction<T>(Future<T> Function(Transaction txn) action) =>
      throw UnimplementedError();
}