feat(llc): add support for type safe filters

Signed-off-by: Sahil Kumar <[email protected]>
2021-04-26 19:55:50 +05:30
parent f2fe9560c7
commit ac995b2fc9
3 changed files with 396 additions and 0 deletions
@@ -0,0 +1,197 @@
+// ignore_for_file: non_constant_identifier_names, constant_identifier_names
+
+const _groupOperators = [
+  FilterOperator.and,
+  FilterOperator.or,
+  FilterOperator.nor,
+];
+
+/// Possible operators to use in filters.
+enum FilterOperator {
+  /// Matches values that are equal to a specified value.
+  equal,
+
+  /// Matches all values that are not equal to a specified value.
+  notEqual,
+
+  /// Matches values that are greater than a specified value.
+  greater,
+
+  /// Matches values that are greater than a specified value.
+  greaterOrEqual,
+
+  /// Matches values that are less than a specified value.
+  less,
+
+  /// Matches values that are less than or equal to a specified value.
+  lessOrEqual,
+
+  /// Matches any of the values specified in an array.
+  in_,
+
+  /// Matches none of the values specified in an array.
+  notIn,
+
+  /// Matches values by performing text search with the specified value.
+  query,
+
+  /// Matches values with the specified prefix.
+  autoComplete,
+
+  /// Matches values that exist/don't exist based on the specified boolean value.
+  exists,
+
+  /// Matches all the values specified in an array.
+  and,
+
+  /// Matches at least one of the values specified in an array.
+  or,
+
+  /// Matches none of the values specified in an array.
+  nor,
+}
+
+/// Helper extension for [FilterOperator]
+extension FilterOperatorX on FilterOperator {
+  /// Converts [FilterOperator] into rew values
+  String get rawValue => {
+        FilterOperator.equal: '\$eq',
+        FilterOperator.notEqual: '\$ne',
+        FilterOperator.greater: '\$gt',
+        FilterOperator.greaterOrEqual: '\$gte',
+        FilterOperator.less: '\$lt',
+        FilterOperator.lessOrEqual: '\$lte',
+        FilterOperator.in_: '\$in',
+        FilterOperator.notIn: '\$nin',
+        FilterOperator.query: '\$q',
+        FilterOperator.autoComplete: '\$autocomplete',
+        FilterOperator.exists: '\$exists',
+        FilterOperator.and: '\$and',
+        FilterOperator.or: '\$or',
+        FilterOperator.nor: '\$nor',
+      }[this]!;
+}
+
+/// Stream supports a limited set of filters for querying channels,
+/// users and members. The example below shows how to filter for channels
+/// of type messaging where the current user is a member
+///
+/// ```dart
+/// val filter = Filter.and(
+///     Filter.equal('type', 'messaging'),
+///     Filter.in_('members', [user.id])
+/// )
+/// ```
+/// See <a href="https://getstream.io/chat/docs/query_channels/?language=dart" target="_top">Query Channels Documentation</a>
+class Filter {
+  const Filter.__({
+    required this.operator,
+    required this.value,
+    this.key,
+  });
+
+  Filter._({
+    required FilterOperator operator,
+    required this.value,
+    this.key,
+  }) : operator = operator.rawValue;
+
+  /// Combines the provided filters and matches the values
+  /// matched by all filters.
+  factory Filter.and(List<Filter> filters) =>
+      Filter._(operator: FilterOperator.and, value: filters);
+
+  /// Combines the provided filters and matches the values
+  /// matched by at least one of the filters.
+  factory Filter.or(List<Filter> filters) =>
+      Filter._(operator: FilterOperator.or, value: filters);
+
+  /// Combines the provided filters and matches the values
+  /// not matched by all the filters.
+  factory Filter.nor(List<Filter> filters) =>
+      Filter._(operator: FilterOperator.nor, value: filters);
+
+  /// Matches values that are equal to a specified value.
+  factory Filter.equal(String key, Object value) =>
+      Filter._(operator: FilterOperator.equal, key: key, value: value);
+
+  /// Matches all values that are not equal to a specified value.
+  factory Filter.notEqual(String key, Object value) =>
+      Filter._(operator: FilterOperator.notEqual, key: key, value: value);
+
+  /// Matches values that are greater than a specified value.
+  factory Filter.greater(String key, Object value) =>
+      Filter._(operator: FilterOperator.greater, key: key, value: value);
+
+  /// Matches values that are greater than a specified value.
+  factory Filter.greaterOrEqual(String key, Object value) =>
+      Filter._(operator: FilterOperator.greaterOrEqual, key: key, value: value);
+
+  /// Matches values that are less than a specified value.
+  factory Filter.less(String key, Object value) =>
+      Filter._(operator: FilterOperator.less, key: key, value: value);
+
+  /// Matches values that are less than or equal to a specified value.
+  factory Filter.lessOrEqual(String key, Object value) =>
+      Filter._(operator: FilterOperator.lessOrEqual, key: key, value: value);
+
+  /// Matches any of the values specified in an array.
+  factory Filter.in_(String key, List<Object> values) =>
+      Filter._(operator: FilterOperator.in_, key: key, value: values);
+
+  /// Matches none of the values specified in an array.
+  factory Filter.notIn(String key, List<Object> values) =>
+      Filter._(operator: FilterOperator.notIn, key: key, value: values);
+
+  /// Matches values by performing text search with the specified value.
+  factory Filter.query(String key, String text) =>
+      Filter._(operator: FilterOperator.query, key: key, value: text);
+
+  /// Matches values with the specified prefix.
+  factory Filter.autoComplete(String key, String text) =>
+      Filter._(operator: FilterOperator.autoComplete, key: key, value: text);
+
+  /// Matches values that exist/don't exist based on the specified boolean value.
+  factory Filter.exists(String key, {bool exists = true}) =>
+      Filter._(operator: FilterOperator.exists, key: key, value: exists);
+
+  /// Creates a custom [Filter] if there isn't one already available.
+  factory Filter.custom({
+    required String operator,
+    required Object value,
+    String? key,
+  }) = Filter.__;
+
+  /// Operator to use in filter.
+  final String operator;
+
+  ///
+  final String? key;
+
+  ///
+  final Object /*List<Object>|List<Filter>|String*/ value;
+
+  ///
+  Map<String, Object> toJson() {
+    final json = <String, Object>{};
+    final groupOperators = _groupOperators.map((it) => it.rawValue);
+
+    assert(
+      groupOperators.contains(operator) || key != null,
+      'Filter must contain the `key` when the operator is not a '
+      'group operator.',
+    );
+
+    if (groupOperators.contains(operator)) {
+      // Filters with group operators are encoded in the following form:
+      // { $<operator>: [ <filter 1>, <filter 2> ] }
+      json[operator] = value;
+    } else {
+      // Normal filters are encoded in the following form:
+      // { key: { $<operator>: <value> } }
+      json[key!] = {operator: value};
+    }
+
+    return json;
+  }
+}