/*
 * QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
 * Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
 *
 * Licensed 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.
*/

using System.Collections;
using System.Collections.Generic;

namespace QuantConnect.Optimizer.Parameters
{
    /// <summary>
    /// Enumerates all possible values for specific optimization parameter
    /// </summary>
    public abstract class OptimizationParameterEnumerator<T> : IEnumerator<string>  where T: OptimizationParameter
    {
        /// <summary>
        /// The target optimization parameter to enumerate
        /// </summary>
        protected T OptimizationParameter { get; }

        /// <summary>
        /// The current enumeration state
        /// </summary>
        protected int Index { get; set; } = -1;

        protected OptimizationParameterEnumerator(T optimizationParameter)
        {
            OptimizationParameter = optimizationParameter;
        }

        /// <summary>
        /// Gets the element in the collection at the current position of the enumerator.
        /// </summary>
        /// <returns>The element in the collection at the current position of the enumerator.</returns>
        public abstract string Current { get; }

        /// <summary>
        /// Gets the current element in the collection.
        /// </summary>
        /// <returns>The current element in the collection.</returns>
        object IEnumerator.Current => Current;

        /// <summary>
        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose() { }

        /// <summary>
        /// Advances the enumerator to the next element of the collection.
        /// </summary>
        /// <returns> true if the enumerator was successfully advanced to the next element; false if the enumerator has passed the end of the collection.</returns>
        /// <exception cref="T:System.InvalidOperationException">The collection was modified after the enumerator was created.</exception>
        public abstract bool MoveNext();

        /// <summary>
        /// Sets the enumerator to its initial position, which is before the first element in the collection.
        /// </summary>
        /// <exception cref="T:System.InvalidOperationException">The collection was modified after the enumerator was created.</exception>
        public void Reset()
        {
            Index = -1;
        }
    }
}