#region License

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#endregion

using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using Gremlin.Net.Process.Traversal;

namespace Gremlin.Net.Driver.Remote
{
    /// <summary>
    ///     A traversal returned from a remote Gremlin Server submission, wrapping a
    ///     <see cref="ResultSet{T}"/> of result objects.
    /// </summary>
    internal class DriverRemoteTraversal<TStart, TEnd> : DefaultTraversal<TStart, TEnd>
    {
        public DriverRemoteTraversal(ResultSet<object> resultSet)
        {
            Traversers = AdaptResults(resultSet);
        }

        /// <inheritdoc />
        public override GremlinLang GremlinLang => throw new NotSupportedException("Remote traversals do not have GremlinLang");

        // Bulked responses arrive as Traversers; non-bulked responses arrive as raw values
        // (e.g. a long for g.V().count()) and are wrapped with a bulk of 1, as the other GLVs do.
        private static async IAsyncEnumerable<Traverser> AdaptResults(ResultSet<object> resultSet,
            [EnumeratorCancellation] CancellationToken cancellationToken = default)
        {
            await foreach (var item in resultSet.WithCancellation(cancellationToken).ConfigureAwait(false))
            {
                yield return item as Traverser ?? new Traverser(item, 1);
            }
        }
    }
}