using System;

namespace MLAPI.Collections

{

/// <summary>

/// Queue with a fixed size

/// </summary>

/// <typeparam name="T">The type of the queue</typeparam>

public sealed class FixedQueue<T>

{

private readonly T[] queue;

private int queueCount = 0;

private int queueStart;

/// <summary>

/// The amount of enqueued objects

/// </summary>

public int Count { get => queueCount; }

/// <summary>

/// Gets the element at a given virtual index

/// </summary>

/// <param name="index">The virtual index to get the item from</param>

/// <returns>The element at the virtual index</returns>

public T this[int index]

{

get

{

return queue[(queueStart + index) % queue.Length];

}

}

/// <summary>

/// Creates a new FixedQueue with a given size

/// </summary>

/// <param name="maxSize">The size of the queue</param>

public FixedQueue(int maxSize)

{

queue = new T[maxSize];

queueStart = 0;

}

/// <summary>

/// Enqueues an object

/// </summary>

/// <param name="t"></param>

/// <returns></returns>

public bool Enqueue(T t)

{

queue[(queueStart + queueCount) % queue.Length] = t;

if (++queueCount > queue.Length)

{

--queueCount;

return true;

}

return false;

}

/// <summary>

/// Dequeues an object

/// </summary>

/// <returns></returns>

public T Dequeue()

{

if (--queueCount == -1) throw new IndexOutOfRangeException("Cannot dequeue empty queue!");

T res = queue[queueStart];

queueStart = (queueStart + 1) % queue.Length;

return res;

}

/// <summary>

/// Gets the element at a given virtual index

/// </summary>

/// <param name="index">The virtual index to get the item from</param>

/// <returns>The element at the virtual index</returns>

public T ElementAt(int index) => queue[(queueStart + index) % queue.Length];

}

}