/*
 * 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.Generic;

namespace QuantConnect.Indicators
{
    /// <summary>
    ///     Interface type used to pass windows around without worry of external modification
    /// </summary>
    /// <typeparam name="T">The type of data in the window</typeparam>
    public interface IReadOnlyWindow<out T> : IEnumerable<T>
    {
        /// <summary>
        ///     Gets the size of this window
        /// </summary>
        int Size { get; }

        /// <summary>
        ///     Gets the current number of elements in this window
        /// </summary>
        int Count { get; }

        /// <summary>
        ///     Gets the number of samples that have been added to this window over its lifetime
        /// </summary>
        int Samples { get; }

        /// <summary>
        ///     Indexes into this window, where index 0 is the most recently
        ///     entered value
        /// </summary>
        /// <param name="i">the index, i</param>
        /// <returns>the ith most recent entry</returns>
        T this[int i] { get; }

        /// <summary>
        ///     Gets a value indicating whether or not this window is ready, i.e,
        ///     it has been filled to its capacity, this is when the Size==Count
        /// </summary>
        bool IsReady { get; }

        /// <summary>
        ///     Gets the most recently removed item from the window. This is the
        ///     piece of data that just 'fell off' as a result of the most recent
        ///     add. If no items have been removed, this will throw an exception.
        /// </summary>
        T MostRecentlyRemoved { get; }
    }
}