// Copyright (c) 2020, 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:analysis_server/src/services/correction/dart/abstract_producer.dart';
import 'package:analysis_server/src/services/correction/fix.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/source/source_range.dart';
import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
import 'package:analyzer_plugin/utilities/range_factory.dart';

class RemoveNameFromCombinator extends CorrectionProducer {
  String _combinatorKind = '';

  @override
  List<Object> get fixArguments => [_combinatorKind];

  @override
  FixKind get fixKind => DartFixKind.REMOVE_NAME_FROM_COMBINATOR;

  @override
  Future<void> compute(ChangeBuilder builder) async {
    var node = coveredNode;
    if (node is SimpleIdentifier) {
      var parent = node.parent;
      if (parent is Combinator) {
        var rangeToRemove = rangeForNameInCombinator(parent, node);
        if (rangeToRemove == null) {
          return;
        }
        await builder.addDartFileEdit(file, (builder) {
          builder.addDeletion(rangeToRemove);
        });
        _combinatorKind = parent is HideCombinator ? 'hide' : 'show';
      }
    }
  }

  /// Return an instance of this class. Used as a tear-off in `FixProcessor`.
  static RemoveNameFromCombinator newInstance() => RemoveNameFromCombinator();

  static SourceRange? rangeForCombinator(Combinator combinator) {
    var parent = combinator.parent;
    if (parent is NamespaceDirective) {
      var combinators = parent.combinators;
      if (combinators.length == 1) {
        var previousToken =
            combinator.parent?.findPrevious(combinator.beginToken);
        if (previousToken != null) {
          return range.endEnd(previousToken, combinator);
        }
        return null;
      }
      var index = combinators.indexOf(combinator);
      if (index < 0) {
        return null;
      } else if (index == combinators.length - 1) {
        return range.endEnd(combinators[index - 1], combinator);
      }
      return range.startStart(combinator, combinators[index + 1]);
    }
    return null;
  }

  static SourceRange? rangeForNameInCombinator(
      Combinator combinator, SimpleIdentifier name) {
    NodeList<SimpleIdentifier> names;
    if (combinator is HideCombinator) {
      names = combinator.hiddenNames;
    } else if (combinator is ShowCombinator) {
      names = combinator.shownNames;
    } else {
      return null;
    }
    if (names.length == 1) {
      return rangeForCombinator(combinator);
    }
    var index = names.indexOf(name);
    if (index < 0) {
      return null;
    } else if (index == names.length - 1) {
      return range.endEnd(names[index - 1], name);
    }
    return range.startStart(name, names[index + 1]);
  }
}