// Copyright (c) 2014, 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.

library services.refactoring;

import 'dart:async';

import 'package:analysis_services/correction/change.dart';
import 'package:analysis_services/correction/status.dart';
import 'package:analysis_services/search/search_engine.dart';
import 'package:analysis_services/src/refactoring/rename_import.dart';
import 'package:analysis_services/src/refactoring/rename_library.dart';
import 'package:analysis_services/src/refactoring/rename_local.dart';
import 'package:analyzer/src/generated/element.dart';


/**
 * Abstract interface for all refactorings.
 */
abstract class Refactoring {
  /**
   * Returns the human readable name of this [Refactoring].
   */
  String get refactoringName;

  /**
   * Checks all conditions - [checkInitialConditions] and
   * [checkFinalConditions] to decide if refactoring can be performed.
   */
  Future<RefactoringStatus> checkAllConditions();

  /**
   * Validates environment to check if this refactoring can be performed.
   *
   * This check may be slow, because many refactorings use search engine.
   */
  Future<RefactoringStatus> checkFinalConditions();

  /**
   * Validates arguments to check if this refactoring can be performed.
   *
   * This check should be quick because it is used often as arguments change.
   */
  Future<RefactoringStatus> checkInitialConditions();

  /**
   * Returns the [Change] to apply to perform this refactoring.
   */
  Future<Change> createChange();

  /**
   * Returs `true` if the [Change] created by refactoring may be unsafe,
   * so we want user to review the [Change] to ensure that he understands it.
   */
  bool requiresPreview();
}


/**
 * Abstract [Refactoring] for renaming some [Element].
 */
abstract class RenameRefactoring implements Refactoring {
  /**
   * Returns a new [RenameRefactoring] instance for renaming [element],
   * maybe `null` if there is no support for renaming [Element]s of the given
   * type.
   */
  factory RenameRefactoring(SearchEngine searchEngine, Element element) {
    if (element is ImportElement) {
      return new RenameImportRefactoringImpl(searchEngine, element);
    }
    if (element is LibraryElement) {
      return new RenameLibraryRefactoringImpl(searchEngine, element);
    }
    if (element is LocalElement) {
      return new RenameLocalRefactoringImpl(searchEngine, element);
    }
    return null;
  }

  /**
   * Sets the new name for the [Element].
   */
  void set newName(String newName);

  /**
   * Returns the old name of the [Element] being renamed.
   */
  String get oldName;

  /**
   * Validates that the [newName] is a valid identifier and is appropriate for
   * the type of the [Element] being renamed.
   *
   * It does not perform all the checks (such as checking for conflicts with any
   * existing names in any of the scopes containing the current name), as many
   * of these checkes require search engine. Use [checkFinalConditions] for this
   * level of checking.
   */
  RefactoringStatus checkNewName();
}