using System.Collections.Generic;

namespace Chernobyl.DesignPatterns.Visitor
{
    /// <summary>
    /// This visitor counts the number of hosts 
    /// it visits.
    /// </summary>
    /// <typeparam name="HostType">The type of the host that this
    /// visitor will be visiting.</typeparam>
    public class CountVisitor<HostType> : IVisitor<HostType> where HostType : IHost<IVisitor<HostType>>
    {
        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="enumerator">The enumerator to use to move through 
        /// the hosts.</param>
        public CountVisitor(IEnumerator<HostType> enumerator)
        {
            Enumerator = enumerator;

            // start visiting the hosts6
            do
            {
                Enumerator.Current.Accept(this);
            } while (Enumerator.MoveNext() != false);
        }

        /// <summary>
        /// Visits a host and updates it's counter.
        /// </summary>
        /// <param name="host">The host to visit</param>
        public void Visit(HostType host)
        {
            ++Count;
        }

        /// <summary>
        /// The number of hosts this visitor has visited.
        /// </summary>
        public uint Count { get; protected set; }

        /// <summary>
        /// Enumerates through the hosts.
        /// </summary>
        IEnumerator<HostType> Enumerator { get; set; }
    }
}