// Copyright (c) 2014, 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 services.completion.contributor.dart.library_prefix;

import 'dart:async';

import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
import 'package:analysis_server/src/services/completion/dart/suggestion_builder.dart';
import 'package:analyzer/src/generated/ast.dart';
import 'package:analyzer/src/generated/element.dart';

import '../../../protocol_server.dart'
    show CompletionSuggestion, CompletionSuggestionKind;

/**
 * A contributor for calculating prefixed import library member suggestions
 * `completion.getSuggestions` request results.
 */
class LibraryPrefixContributor extends DartCompletionContributor {
  @override
  Future<List<CompletionSuggestion>> computeSuggestions(
      DartCompletionRequest request) async {
    if (!request.includeIdentifiers) {
      return EMPTY_LIST;
    }

    List<Directive> directives = await request.resolveDirectives();
    if (directives == null) {
      return EMPTY_LIST;
    }

    List<CompletionSuggestion> suggestions = <CompletionSuggestion>[];
    for (Directive directive in directives) {
      if (directive is ImportDirective) {
        SimpleIdentifier prefix = directive.prefix;
        ImportElement element = directive.element;
        if (prefix != null && element != null) {
          String completion = prefix.name;
          LibraryElement libElem = element.importedLibrary;
          if (completion != null && completion.length > 0 && libElem != null) {
            CompletionSuggestion suggestion = createSuggestion(libElem,
                completion: completion,
                kind: CompletionSuggestionKind.IDENTIFIER);
            if (suggestion != null) {
              suggestions.add(suggestion);
            }
          }
        }
      }
    }
    return suggestions;
  }
}