// 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:_fe_analyzer_shared/src/scanner/token.dart';
import 'package:analysis_server/src/services/correction/fix.dart';
import 'package:analysis_server_plugin/edit/dart/correction_producer.dart';
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/element/element.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 MakeVariableNotFinal extends ResolvedCorrectionProducer {
  String _variableName = '';

  new({required super.context});

  @override
  CorrectionApplicability get applicability =>
      // TODO(applicability): comment on why.
      CorrectionApplicability.singleLocation;

  @override
  List<String> get fixArguments => [_variableName];

  @override
  FixKind get fixKind => DartFixKind.makeVariableNotFinal;

  @override
  Future<void> compute(ChangeBuilder builder) async {
    var node = this.node;
    if (node is! SimpleIdentifier) {
      return;
    }

    var variable = node.element;
    if (variable is! LocalVariableElement) {
      return;
    }

    var variableName = variable.name;
    if (variableName == null) {
      return;
    }

    var nameOffset = variable.firstFragment.nameOffset;
    if (nameOffset == null) {
      return;
    }

    var declaration = unit.nodeCovering(offset: nameOffset);
    var declarationList = declaration?.parent;

    if (declaration is VariableDeclaration &&
        declarationList is VariableDeclarationList) {
      var keywordToken = declarationList.keyword;
      if (declarationList.variables.length == 1 &&
          keywordToken != null &&
          keywordToken.keyword == Keyword.FINAL) {
        await builder.addDartFileEdit(file, (builder) {
          var typeAnnotation = declarationList.type;
          if (typeAnnotation != null) {
            builder.addDeletion(range.startStart(keywordToken, typeAnnotation));
          } else {
            builder.addSimpleReplacement(range.token(keywordToken), 'var');
          }
        });
        _variableName = variableName;
      }
    }
  }
}
