/*
 * Copyright (c) 2014 Google Inc.
 *
 * All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse
 * Public License v1.0 which accompanies this distribution, and is available at
 *
 * http://www.eclipse.org/legal/epl-v10.html
 */
package com.google.eclipse.protobuf.scoping;

import static com.google.common.collect.Sets.newHashSet;
import static org.eclipse.xtext.resource.EObjectDescription.create;

import com.google.common.base.Strings;
import com.google.common.collect.ImmutableSet;
import com.google.eclipse.protobuf.model.util.MessageFields;
import com.google.eclipse.protobuf.protobuf.Group;
import com.google.eclipse.protobuf.protobuf.IndexedElement;
import com.google.eclipse.protobuf.protobuf.Message;
import com.google.eclipse.protobuf.protobuf.MessageField;
import com.google.eclipse.protobuf.protobuf.OneOf;
import com.google.inject.Inject;

import org.eclipse.emf.ecore.EObject;
import org.eclipse.xtext.resource.IEObjectDescription;

import java.util.Collection;
import java.util.Set;

/**
 * @author alruiz@google.com (Alex Ruiz)
 */
class NormalFieldNameFinderStrategy implements CustomOptionFieldNameFinder.FinderStrategy {
  @Inject private MessageFields messageFields;

  @Override public Collection<IEObjectDescription> findMessageFields(IndexedElement reference) {
    Iterable<? extends EObject> elements;
    if (reference instanceof Group) {
      elements = ((Group) reference).getElements();
    } else if (reference instanceof MessageField) {
      MessageField field = (MessageField) reference;
      Message fieldType = messageFields.mapEntryTypeOf(field);
      if (fieldType == null) {
        fieldType = messageFields.messageTypeOf(field);
      }
      elements = fieldType.getElements();
    } else {
      elements = null;
    }
    return getDescriptions(elements);
  }

  private Set<IEObjectDescription> getDescriptions(Iterable<? extends EObject> elements) {
    if (elements == null) {
      return ImmutableSet.of();
    }
    Set<IEObjectDescription> descriptions = newHashSet();
    for (EObject element : elements) {
      if (element instanceof MessageField) {
        String name = ((MessageField) element).getName();
        descriptions.add(create(name, element));
      } else if (element instanceof Group) {
        String name = ((Group) element).getName();
        if (!Strings.isNullOrEmpty(name)) {
          descriptions.add(create(name, element));
        }
      } else if (element instanceof OneOf) {
        descriptions.addAll(getDescriptions(((OneOf) element).getElements()));
      }
    }
    return descriptions;
  }
}