// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:analyzer/dart/element/element.dart';

/// The result of attempting to resolve an identifier to elements.
class ResolutionResult {
  /// An instance that can be used anywhere that no element was found.
  static const ResolutionResult none =
      ResolutionResult._(_ResolutionResultState.none);

  /// An instance that can be used anywhere that multiple elements were found.
  static const ResolutionResult ambiguous =
      ResolutionResult._(_ResolutionResultState.ambiguous);

  /// The state of the result.
  final _ResolutionResultState state;

  /// Return the element that is invoked for reading.
  final ExecutableElement getter;

  /// Return the element that is invoked for writing.
  final ExecutableElement setter;

  /// Initialize a newly created result to represent resolving a single
  /// reading and / or writing result.
  ResolutionResult({this.getter, this.setter})
      : assert(getter != null || setter != null),
        state = _ResolutionResultState.single;

  /// Initialize a newly created result with no elements and the given [state].
  const ResolutionResult._(this.state)
      : getter = null,
        setter = null;

  /// Return `true` if this result represents the case where multiple ambiguous
  /// elements were found.
  bool get isAmbiguous => state == _ResolutionResultState.ambiguous;

  /// Return `true` if this result represents the case where no element was
  /// found.
  bool get isNone => state == _ResolutionResultState.none;

  /// Return `true` if this result represents the case where a single element
  /// was found.
  bool get isSingle => state == _ResolutionResultState.single;

  /// If this is a property, return `true` is the property is static.
  /// If this is a function, return `true` is the function is static.
  /// Otherwise return `false`.
  bool get isStatic {
    return getter?.isStatic ?? setter?.isStatic ?? false;
  }
}

/// The state of a [ResolutionResult].
enum _ResolutionResultState {
  /// Indicates that no element was found.
  none,

  /// Indicates that a single element was found.
  single,

  /// Indicates that multiple ambiguous elements were found.
  ambiguous
}