// Copyright (c) 2017, 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:analyzer/dart/analysis/results.dart';
import 'package:analyzer/diagnostic/diagnostic.dart';
import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer_plugin/protocol/protocol.dart';
import 'package:analyzer_plugin/protocol/protocol_generated.dart';
import 'package:analyzer_plugin/src/utilities/fixes/fixes.dart';
import 'package:analyzer_plugin/utilities/generator.dart';

/// The information about a requested set of fixes when computing fixes in a
/// `.dart` file.
///
/// Clients may not extend, implement or mix-in this class.
abstract class DartFixesRequest implements FixesRequest {
  /// The analysis result for the file in which the fixes are being requested.
  ResolvedUnitResult get result;
}

/// An object that [FixContributor]s use to record fixes.
///
/// Clients may not extend, implement or mix-in this class.
abstract class FixCollector {
  /// Records a new [change] (fix) associated with the given [diagnostic].
  void addFix(Diagnostic diagnostic, PrioritizedSourceChange change);
}

/// An object used to produce fixes.
///
/// Clients may implement this class when implementing plugins.
abstract class FixContributor {
  /// Contribute fixes for the location in the file specified by the given
  /// [request] into the given [collector].
  Future<void> computeFixes(
    covariant FixesRequest request,
    FixCollector collector,
  );
}

/// The information about a requested set of fixes.
///
/// Clients may not extend, implement or mix-in this class.
abstract class FixesRequest {
  /// The analysis error to be fixed, or `null` if the error has not been
  /// determined.
  List<Diagnostic> get errorsToFix;

  /// Return the offset within the source for which fixes are being requested.
  int get offset;

  /// Return the resource provider associated with this request.
  ResourceProvider get resourceProvider;
}

/// A generator that will generate an 'edit.getFixes' response.
///
/// Clients may not extend, implement or mix-in this class.
class FixGenerator {
  /// The contributors to be used to generate the fixes.
  final List<FixContributor> contributors;

  /// Initialize a newly created fix generator to use the given [contributors].
  FixGenerator(this.contributors);

  /// Create an 'edit.getFixes' response for the location in the file specified
  /// by the given [request]. If any of the contributors throws an exception,
  /// also create a non-fatal 'plugin.error' notification.
  Future<GeneratorResult<EditGetFixesResult>> generateFixesResponse(
    FixesRequest request,
  ) async {
    var notifications = <Notification>[];
    var collector = FixCollectorImpl();
    for (var contributor in contributors) {
      try {
        await contributor.computeFixes(request, collector);
      } catch (exception, stackTrace) {
        notifications.add(
          PluginErrorParams(
            false,
            exception.toString(),
            stackTrace.toString(),
          ).toNotification(),
        );
      }
    }
    var result = EditGetFixesResult(collector.fixes);
    return GeneratorResult(result, notifications);
  }
}

/// A description of a class of fixes. Instances are intended to hold the
/// information that is common across a number of fixes and to be shared by those
/// fixes. For example, if an unnecessary cast is found then one of the suggested
/// fixes will be to remove the cast. If there are multiple unnecessary casts in
/// a single file, then there will be multiple fixes, one per occurrence, but
/// they will all share the same kind.
///
/// Clients may not extend, implement or mix-in this class.
class FixKind {
  /// The unique identifier of this kind of assist. May be used by client editors,
  /// for example to allow key-binding specific fixes (or groups of).
  final String id;

  /// The priority of this kind of fix for the kind of error being addressed
  /// where a higher integer value indicates a higher priority and relevance.
  final int priority;

  /// A human-readable description of the changes that will be applied by this
  /// kind of fix. The message can contain parameters, where each parameter is
  /// represented by a zero-based index inside curly braces. For example, the
  /// message `"Create a component named '{0}' in '{1}'"` contains two parameters.
  final String message;

  /// Initialize a newly created kind of fix to have the given [id],
  /// [priority], and [message].
  const FixKind(this.id, this.priority, this.message);

  @override
  int get hashCode => id.hashCode;

  @override
  bool operator ==(other) => other is FixKind && other.id == id;

  @override
  String toString() => id;
}