// 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.

import 'dart:async';

import 'package:analysis_server/src/protocol_server.dart'
    hide Element, ElementKind;
import 'package:analysis_server/src/services/correction/status.dart';
import 'package:analysis_server/src/services/correction/util.dart';
import 'package:analysis_server/src/services/refactoring/naming_conventions.dart';
import 'package:analysis_server/src/services/refactoring/refactoring.dart';
import 'package:analysis_server/src/services/refactoring/rename.dart';
import 'package:analysis_server/src/services/search/hierarchy.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/src/dart/analysis/session_helper.dart';
import 'package:analyzer/src/generated/source.dart';

/**
 * A [Refactoring] for renaming [LocalElement]s.
 */
class RenameLocalRefactoringImpl extends RenameRefactoringImpl {
  final AnalysisSessionHelper sessionHelper;

  List<LocalElement> elements = [];

  RenameLocalRefactoringImpl(
      RefactoringWorkspace workspace, LocalElement element)
      : sessionHelper = AnalysisSessionHelper(element.session),
        super(workspace, element);

  @override
  LocalElement get element => super.element as LocalElement;

  @override
  String get refactoringName {
    if (element is ParameterElement) {
      return "Rename Parameter";
    }
    if (element is FunctionElement) {
      return "Rename Local Function";
    }
    return "Rename Local Variable";
  }

  @override
  Future<RefactoringStatus> checkFinalConditions() async {
    // TODO(brianwilkerson) Determine whether this await is necessary.
    await null;
    RefactoringStatus result = new RefactoringStatus();
    await _prepareElements();
    for (LocalElement element in elements) {
      var resolvedUnit = await sessionHelper.getResolvedUnitByElement(element);
      var unit = resolvedUnit.unit;
      unit.accept(new _ConflictValidatorVisitor(result, newName, element));
    }
    return result;
  }

  @override
  RefactoringStatus checkNewName() {
    RefactoringStatus result = super.checkNewName();
    if (element is LocalVariableElement) {
      result.addStatus(validateVariableName(newName));
    } else if (element is ParameterElement) {
      result.addStatus(validateParameterName(newName));
    } else if (element is FunctionElement) {
      result.addStatus(validateFunctionName(newName));
    }
    return result;
  }

  @override
  Future<void> fillChange() async {
    var processor = new RenameProcessor(workspace, change, newName);
    for (Element element in elements) {
      processor.addDeclarationEdit(element);
      var references = await searchEngine.searchReferences(element);

      // Exclude "implicit" references to optional positional parameters.
      if (element is ParameterElement && element.isOptionalPositional) {
        references.removeWhere((match) => match.sourceRange.length == 0);
      }

      processor.addReferenceEdits(references);
    }
  }

  /**
   * Fills [elements] with [Element]s to rename.
   */
  Future _prepareElements() async {
    // TODO(brianwilkerson) Determine whether this await is necessary.
    await null;
    Element element = this.element;
    if (element is ParameterElement && element.isNamed) {
      elements = await getHierarchyNamedParameters(searchEngine, element);
    } else {
      elements = [element];
    }
  }
}

class _ConflictValidatorVisitor extends RecursiveAstVisitor {
  final RefactoringStatus result;
  final String newName;
  final LocalElement target;
  final Set<Element> conflictingLocals = new Set<Element>();

  _ConflictValidatorVisitor(this.result, this.newName, this.target);

  @override
  visitSimpleIdentifier(SimpleIdentifier node) {
    Element nodeElement = node.staticElement;
    if (nodeElement != null && nodeElement.name == newName) {
      // Duplicate declaration.
      if (node.inDeclarationContext() && _isVisibleWithTarget(nodeElement)) {
        conflictingLocals.add(nodeElement);
        String nodeKind = nodeElement.kind.displayName;
        String message = "Duplicate $nodeKind '$newName'.";
        result.addError(message, newLocation_fromElement(nodeElement));
        return;
      }
      if (conflictingLocals.contains(nodeElement)) {
        return;
      }
      // Shadowing by the target element.
      SourceRange targetRange = target.visibleRange;
      if (targetRange != null &&
          targetRange.contains(node.offset) &&
          !node.isQualified &&
          !_isNamedExpressionName(node)) {
        nodeElement = getSyntheticAccessorVariable(nodeElement);
        String nodeKind = nodeElement.kind.displayName;
        String nodeName = getElementQualifiedName(nodeElement);
        String nameElementSourceName = nodeElement.source.shortName;
        String refKind = target.kind.displayName;
        String message = 'Usage of $nodeKind "$nodeName" declared in '
            '"$nameElementSourceName" will be shadowed by renamed $refKind.';
        result.addError(message, newLocation_fromNode(node));
      }
    }
  }

  /**
   * Returns whether [element] and [target] are visible together.
   */
  bool _isVisibleWithTarget(Element element) {
    if (element is LocalElement) {
      SourceRange targetRange = target.visibleRange;
      SourceRange elementRange = element.visibleRange;
      return targetRange != null &&
          elementRange != null &&
          elementRange.intersects(targetRange);
    }
    return false;
  }

  static bool _isNamedExpressionName(SimpleIdentifier node) {
    return node.parent is Label && node.parent.parent is NamedExpression;
  }
}