// 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.

// @dart = 2.9

import 'package:analysis_server/plugin/analysis/occurrences/occurrences_core.dart';
import 'package:analysis_server/src/protocol_server.dart' as protocol;
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/src/dart/ast/extensions.dart';
import 'package:analyzer/src/dart/element/element.dart';

void addDartOccurrences(OccurrencesCollector collector, CompilationUnit unit) {
  var visitor = _DartUnitOccurrencesComputerVisitor();
  unit.accept(visitor);
  visitor.elementsOffsets.forEach((engineElement, offsets) {
    var length = engineElement.nameLength;
    var serverElement = protocol.convertElement(engineElement);
    var occurrences = protocol.Occurrences(serverElement, offsets, length);
    collector.addOccurrences(occurrences);
  });
}

class _DartUnitOccurrencesComputerVisitor extends RecursiveAstVisitor<void> {
  final Map<Element, List<int>> elementsOffsets = <Element, List<int>>{};

  @override
  void visitSimpleIdentifier(SimpleIdentifier node) {
    var element = node.writeOrReadElement;
    if (element != null) {
      _addOccurrence(element, node.offset);
    }
    return super.visitSimpleIdentifier(node);
  }

  void _addOccurrence(Element element, int offset) {
    element = _canonicalizeElement(element);
    if (element == null || element == DynamicElementImpl.instance) {
      return;
    }
    var offsets = elementsOffsets[element];
    if (offsets == null) {
      offsets = <int>[];
      elementsOffsets[element] = offsets;
    }
    offsets.add(offset);
  }

  Element _canonicalizeElement(Element element) {
    if (element is FieldFormalParameterElement) {
      element = (element as FieldFormalParameterElement).field;
    }
    if (element is PropertyAccessorElement) {
      element = (element as PropertyAccessorElement).variable;
    }
    return element?.declaration;
  }
}