// 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/dart/element/element.dart';
import 'package:analyzer/file_system/file_system.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 CreateClass extends CorrectionProducer {
  String className = '';

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

  @override
  FixKind get fixKind => DartFixKind.CREATE_CLASS;

  @override
  Future<void> compute(ChangeBuilder builder) async {
    var targetNode = node;
    Element? prefixElement;
    SimpleIdentifier nameNode;
    ArgumentList? arguments;

    if (targetNode is Annotation) {
      var name = targetNode.name;
      arguments = targetNode.arguments;
      if (name.staticElement != null || arguments == null) {
        // TODO(brianwilkerson) Consider supporting creating a class when the
        //  arguments are missing by also adding an empty argument list.
        return;
      }
      targetNode = name;
    }
    if (targetNode is SimpleIdentifier) {
      nameNode = targetNode;
    } else if (targetNode is PrefixedIdentifier) {
      prefixElement = targetNode.prefix.staticElement;
      if (prefixElement == null) {
        return;
      }
      nameNode = targetNode.identifier;
    } else {
      return;
    }
    if (!mightBeTypeIdentifier(nameNode)) {
      return;
    }
    className = nameNode.name;
    // prepare environment
    Element targetUnit;
    var prefix = '';
    var suffix = '';
    var offset = -1;
    String? filePath;
    if (prefixElement == null) {
      targetUnit = unit.declaredElement!;
      var enclosingMember = targetNode.thisOrAncestorMatching((node) =>
          node is CompilationUnitMember && node.parent is CompilationUnit);
      if (enclosingMember == null) {
        return;
      }
      offset = enclosingMember.end;
      filePath = file;
      prefix = '$eol$eol';
    } else {
      for (var import in libraryElement.imports) {
        if (prefixElement is PrefixElement && import.prefix == prefixElement) {
          var library = import.importedLibrary;
          if (library != null) {
            targetUnit = library.definingCompilationUnit;
            var targetSource = targetUnit.source!;
            try {
              offset = targetSource.contents.data.length;
              filePath = targetSource.fullName;
              prefix = '$eol';
              suffix = '$eol';
            } on FileSystemException {
              // If we can't read the file to get the offset, then we can't
              // create a fix.
            }
            break;
          }
        }
      }
    }
    if (filePath == null || offset < 0) {
      return;
    }
    await builder.addDartFileEdit(filePath, (builder) {
      builder.addInsertion(offset, (builder) {
        builder.write(prefix);
        if (arguments == null) {
          builder.writeClassDeclaration(className, nameGroupName: 'NAME');
        } else {
          builder.writeClassDeclaration(className, nameGroupName: 'NAME',
              membersWriter: () {
            builder.write('  ');
            builder.writeConstructorDeclaration(className,
                argumentList: arguments,
                classNameGroupName: 'NAME',
                isConst: true);
            builder.writeln();
          });
        }
        builder.write(suffix);
      });
      if (prefixElement == null) {
        builder.addLinkedPosition(range.node(targetNode), 'NAME');
      }
    });
  }

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