using System.Linq;

namespace Lucene.Net.Queries.Function.ValueSources
{
    /*
     * 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.
     */

    /// <summary>
    /// <see cref="ProductSingleFunction"/> returns the product of it's components.
    /// <para/>
    /// NOTE: This was ProductFloatFunction in Lucene
    /// </summary>
    public class ProductSingleFunction : MultiSingleFunction
    {
        public ProductSingleFunction(ValueSource[] sources)
            : base(sources)
        {
        }

        protected override string Name
        {
            get { return "product"; }
        }

        protected override float Func(int doc, FunctionValues[] valsArr)
        {
            return valsArr.Aggregate(1.0f, (current, vals) => current * vals.SingleVal(doc));
        }
    }
}