// 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_server/plugin/protocol/protocol.dart'
    show RefactoringMethodParameter, SourceChange;
import 'package:analysis_server/src/services/correction/status.dart';
import 'package:analysis_server/src/services/refactoring/convert_getter_to_method.dart';
import 'package:analysis_server/src/services/refactoring/convert_method_to_getter.dart';
import 'package:analysis_server/src/services/refactoring/extract_local.dart';
import 'package:analysis_server/src/services/refactoring/extract_method.dart';
import 'package:analysis_server/src/services/refactoring/inline_local.dart';
import 'package:analysis_server/src/services/refactoring/inline_method.dart';
import 'package:analysis_server/src/services/refactoring/move_file.dart';
import 'package:analysis_server/src/services/refactoring/rename_class_member.dart';
import 'package:analysis_server/src/services/refactoring/rename_constructor.dart';
import 'package:analysis_server/src/services/refactoring/rename_import.dart';
import 'package:analysis_server/src/services/refactoring/rename_label.dart';
import 'package:analysis_server/src/services/refactoring/rename_library.dart';
import 'package:analysis_server/src/services/refactoring/rename_local.dart';
import 'package:analysis_server/src/services/refactoring/rename_unit_member.dart';
import 'package:analysis_server/src/services/search/search_engine.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer/src/dart/element/ast_provider.dart';
import 'package:analyzer/src/generated/engine.dart';
import 'package:analyzer/src/generated/source.dart';

/**
 * [Refactoring] to convert getters into normal [MethodDeclaration]s.
 */
abstract class ConvertGetterToMethodRefactoring implements Refactoring {
  /**
   * Returns a new [ConvertMethodToGetterRefactoring] instance for converting
   * [element] and all the corresponding hierarchy elements.
   */
  factory ConvertGetterToMethodRefactoring(SearchEngine searchEngine,
      AstProvider astProvider, PropertyAccessorElement element) {
    return new ConvertGetterToMethodRefactoringImpl(
        searchEngine, astProvider, element);
  }
}

/**
 * [Refactoring] to convert normal [MethodDeclaration]s into getters.
 */
abstract class ConvertMethodToGetterRefactoring implements Refactoring {
  /**
   * Returns a new [ConvertMethodToGetterRefactoring] instance for converting
   * [element] and all the corresponding hierarchy elements.
   */
  factory ConvertMethodToGetterRefactoring(SearchEngine searchEngine,
      AstProvider astProvider, ExecutableElement element) {
    return new ConvertMethodToGetterRefactoringImpl(
        searchEngine, astProvider, element);
  }
}

/**
 * [Refactoring] to extract an expression into a local variable declaration.
 */
abstract class ExtractLocalRefactoring implements Refactoring {
  /**
   * Returns a new [ExtractLocalRefactoring] instance.
   */
  factory ExtractLocalRefactoring(
      CompilationUnit unit, int selectionOffset, int selectionLength) {
    return new ExtractLocalRefactoringImpl(
        unit, selectionOffset, selectionLength);
  }

  /**
   * The lengths of the expressions that cover the specified selection,
   * from the down most to the up most.
   */
  List<int> get coveringExpressionLengths;

  /**
   * The offsets of the expressions that cover the specified selection,
   * from the down most to the up most.
   */
  List<int> get coveringExpressionOffsets;

  /**
   * True if all occurrences of the expression within the scope in which the
   * variable will be defined should be replaced by a reference to the local
   * variable. The expression used to initiate the refactoring will always be
   * replaced.
   */
  void set extractAll(bool extractAll);

  /**
   * The lengths of the expressions that would be replaced by a reference to the
   * variable. The lengths correspond to the offsets. In other words, for a
   * given expression, if the offset of that expression is offsets[i], then the
   * length of that expression is lengths[i].
   */
  List<int> get lengths;

  /**
   * The name that the local variable should be given.
   */
  void set name(String name);

  /**
   * The proposed names for the local variable.
   *
   * The first proposal should be used as the "best guess" (if it exists).
   */
  List<String> get names;

  /**
   * The offsets of the expressions that would be replaced by a reference to
   * the variable.
   */
  List<int> get offsets;

  /**
   * Validates that the [name] is a valid identifier and is appropriate for
   * local variable.
   *
   * 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 checkName();
}

/**
 * [Refactoring] to extract an [Expression] or [Statement]s into a new method.
 */
abstract class ExtractMethodRefactoring implements Refactoring {
  /**
   * Returns a new [ExtractMethodRefactoring] instance.
   */
  factory ExtractMethodRefactoring(SearchEngine searchEngine,
      CompilationUnit unit, int selectionOffset, int selectionLength) {
    return new ExtractMethodRefactoringImpl(
        searchEngine, unit, selectionOffset, selectionLength);
  }

  /**
   * True if a getter could be created rather than a method.
   */
  bool get canCreateGetter;

  /**
   * True if a getter should be created rather than a method.
   */
  void set createGetter(bool createGetter);

  /**
   * True if all occurrences of the expression or statements should be replaced
   * by an invocation of the method. The expression or statements used to
   * initiate the refactoring will always be replaced.
   */
  void set extractAll(bool extractAll);

  /**
   * The lengths of the expressions or statements that would be replaced by an
   * invocation of the method. The lengths correspond to the offsets.
   * In other words, for a given expression (or block of statements), if the
   * offset of that expression is offsets[i], then the length of that expression
   * is lengths[i].
   */
  List<int> get lengths;

  /**
   * The name that the method should be given.
   */
  void set name(String name);

  /**
   * The proposed names for the method.
   *
   * The first proposal should be used as the "best guess" (if it exists).
   */
  List<String> get names;

  /**
   * The offsets of the expressions or statements that would be replaced by an
   * invocation of the method.
   */
  List<int> get offsets;

  /**
   * The proposed parameters for the method.
   */
  List<RefactoringMethodParameter> get parameters;

  /**
   * The parameters that should be defined for the method.
   */
  void set parameters(List<RefactoringMethodParameter> parameters);

  /**
   * The proposed return type for the method.
   */
  String get returnType;

  /**
   * The return type that should be defined for the method.
   */
  void set returnType(String returnType);

  /**
   * Validates that the [name] is a valid identifier and is appropriate for a
   * method.
   *
   * 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 checkName();
}

/**
 * [Refactoring] to inline a local [VariableElement].
 */
abstract class InlineLocalRefactoring implements Refactoring {
  /**
   * Returns a new [InlineLocalRefactoring] instance.
   */
  factory InlineLocalRefactoring(SearchEngine searchEngine,
      AstProvider astProvider, CompilationUnit unit, int offset) {
    return new InlineLocalRefactoringImpl(
        searchEngine, astProvider, unit, offset);
  }

  /**
   * Returns the number of references to the [VariableElement].
   */
  int get referenceCount;

  /**
   * Returns the name of the variable being inlined.
   */
  String get variableName;
}

/**
 * [Refactoring] to inline an [ExecutableElement].
 */
abstract class InlineMethodRefactoring implements Refactoring {
  /**
   * Returns a new [InlineMethodRefactoring] instance.
   */
  factory InlineMethodRefactoring(SearchEngine searchEngine,
      AstProvider astProvider, CompilationUnit unit, int offset) {
    return new InlineMethodRefactoringImpl(
        searchEngine, astProvider, unit, offset);
  }

  /**
   * The name of the class enclosing the method being inlined.
   * If not a class member is being inlined, then `null`.
   */
  String get className;

  /**
   * True if the method being inlined should be removed.
   * It is an error if this field is `true` and [inlineAll] is `false`.
   */
  void set deleteSource(bool deleteSource);

  /**
   * True if all invocations of the method should be inlined, or false if only
   * the invocation site used to create this refactoring should be inlined.
   */
  void set inlineAll(bool inlineAll);

  /**
   * True if the declaration of the method is selected.
   * So, all references should be inlined.
   */
  bool get isDeclaration;

  /**
   * The name of the method (or function) being inlined.
   */
  String get methodName;
}

/**
 * [Refactoring] to move/rename a file.
 */
abstract class MoveFileRefactoring implements Refactoring {
  /**
   * Returns a new [MoveFileRefactoring] instance.
   */
  factory MoveFileRefactoring(
      ResourceProvider resourceProvider,
      SearchEngine searchEngine,
      AnalysisContext context,
      Source source,
      String oldFile) {
    return new MoveFileRefactoringImpl(
        resourceProvider, searchEngine, context, source, oldFile);
  }

  /**
   * The new file path to which the given file is being moved.
   */
  void set newFile(String newName);
}

/**
 * Abstract interface for all refactorings.
 */
abstract class Refactoring {
  /**
   * The ids of source edits that are not known to be valid.
   *
   * An edit is not known to be valid if there was insufficient type information
   * for the server to be able to determine whether or not the code needs to be
   * modified, such as when a member is being renamed and there is a reference
   * to a member from an unknown type. This field will be omitted if the change
   * field is omitted or if there are no potential edits for the refactoring.
   */
  List<String> get potentialEditIds;

  /**
   * 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<SourceChange> 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, AstProvider astProvider, Element element) {
    if (element == null) {
      return null;
    }
    if (element is PropertyAccessorElement) {
      element = (element as PropertyAccessorElement).variable;
    }
    if (element.enclosingElement is CompilationUnitElement) {
      return new RenameUnitMemberRefactoringImpl(searchEngine, element);
    }
    if (element is ConstructorElement) {
      return new RenameConstructorRefactoringImpl(
          searchEngine, astProvider, element);
    }
    if (element is ImportElement) {
      return new RenameImportRefactoringImpl(searchEngine, element);
    }
    if (element is LabelElement) {
      return new RenameLabelRefactoringImpl(searchEngine, element);
    }
    if (element is LibraryElement) {
      return new RenameLibraryRefactoringImpl(searchEngine, element);
    }
    if (element is LocalElement) {
      return new RenameLocalRefactoringImpl(searchEngine, astProvider, element);
    }
    if (element.enclosingElement is ClassElement) {
      return new RenameClassMemberRefactoringImpl(searchEngine, element);
    }
    return null;
  }

  /**
   * Returns the human-readable description of the kind of element being renamed
   * (such as “class” or “function type alias”).
   */
  String get elementKindName;

  /**
   * 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();
}

/**
 * Cache for accessing resolved [CompilationUnit]s by [Element]s.
 *
 * Must by short-lived.
 *
 * TODO(scheglov) consider moving to request-bound object.
 */
class ResolvedUnitCache {
  final AstProvider _astProvider;
  final Map<CompilationUnitElement, CompilationUnit> _map = {};

  ResolvedUnitCache(this._astProvider, [CompilationUnit unit]) {
    if (unit != null) {
      _map[unit.element] = unit;
    }
  }

  Future<CompilationUnit> getUnit(Element element) async {
    CompilationUnitElement unitElement =
        element.getAncestor((e) => e is CompilationUnitElement)
            as CompilationUnitElement;
    CompilationUnit unit = _map[unitElement];
    if (unit == null) {
      unit = await _astProvider.getResolvedUnitForElement(element);
      _map[unitElement] = unit;
    }
    return unit;
  }
}