// Copyright (c) 2015, 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.

library analysis_server.src.services.completion.completion_core;

import 'package:analysis_server/src/provisional/completion/completion_core.dart';
import 'package:analysis_server/src/services/completion/completion_performance.dart';
import 'package:analysis_server/src/services/search/search_engine.dart';
import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer/src/generated/engine.dart';
import 'package:analyzer/src/generated/source.dart';

/**
 * The information about a requested list of completions.
 */
class CompletionRequestImpl implements CompletionRequest {
  @override
  final AnalysisContext context;

  @override
  final Source source;

  @override
  final int offset;

  /**
   * The offset of the start of the text to be replaced.
   * This will be different than the [offset] used to request the completion
   * suggestions if there was a portion of an identifier before the original
   * [offset]. In particular, the [replacementOffset] will be the offset of the
   * beginning of said identifier.
   */
  int replacementOffset;

  /**
   * The length of the text to be replaced if the remainder of the identifier
   * containing the cursor is to be replaced when the suggestion is applied
   * (that is, the number of characters in the existing identifier).
   * This will be different than the [replacementOffset] - [offset]
   * if the [offset] is in the middle of an existing identifier.
   */
  int replacementLength;

  @override
  final ResourceProvider resourceProvider;

  @override
  final SearchEngine searchEngine;

  final CompletionPerformance performance;

  /**
   * Initialize a newly created completion request based on the given arguments.
   */
  CompletionRequestImpl(this.context, this.resourceProvider, this.searchEngine,
      this.source, this.offset, this.performance) {
    replacementOffset = offset;
    replacementLength = 0;
  }

  /**
   * Return the original text from the [replacementOffset] to the [offset]
   * that can be used to filter the suggestions on the server side.
   */
  String get filterText {
    return context
        .getContents(source)
        .data
        .substring(replacementOffset, offset);
  }
}