// 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/file_system/file_system.dart';
import 'package:analyzer_plugin/protocol/protocol_common.dart';
import 'package:analyzer_plugin/utilities/completion/completion_core.dart';

/// An object that can collect completion suggestions.
class CompletionCollectorImpl implements CompletionCollector {
  /// The length of the region of text that should be replaced by the selected
  /// completion suggestion.
  int _length;

  /// The offset of the region of text that should be replaced by the selected
  /// completion suggestion.
  int _offset;

  /// A list of the completion suggestions that have been collected.
  List<CompletionSuggestion> suggestions = <CompletionSuggestion>[];

  /// Initialize a newly created completion collector.
  CompletionCollectorImpl();

  /// Return the length of the region of text that should be replaced by the
  /// selected completion suggestion, or `null` if the length has not been set.
  int get length => _length;

  @override
  set length(int length) {
    if (_length != null) {
      throw StateError('The length can only be set once');
    }
    _length = length;
  }

  /// Return the offset of the region of text that should be replaced by the
  /// selected completion suggestion, or `null` if the offset has not been set.
  int get offset => _offset;

  @override
  set offset(int length) {
    if (_offset != null) {
      throw StateError('The offset can only be set once');
    }
    _offset = length;
  }

  @override
  bool get offsetIsSet => offset != null;

  @override
  int get suggestionsLength => suggestions.length;

  @override
  void addSuggestion(CompletionSuggestion suggestion) {
    suggestions.add(suggestion);
  }
}

/// A concrete implementation of [DartCompletionRequest].
class DartCompletionRequestImpl implements DartCompletionRequest {
  @override
  final ResourceProvider resourceProvider;

  @override
  final int offset;

  @override
  final ResolvedUnitResult result;

  /// A flag indicating whether completion has been aborted.
  bool _aborted = false;

  /// Initialize a newly created request.
  DartCompletionRequestImpl(this.resourceProvider, this.offset, this.result);

  /// Abort the current completion request.
  void abort() {
    _aborted = true;
  }

  @override
  void checkAborted() {
    if (_aborted) {
      throw AbortCompletion();
    }
  }
}