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using System;
using System.Collections.Generic;
using System.Threading;
using XenAdmin.Wizards.CrossPoolMigrateWizard.Filters;
using XenAdmin.Wizards.GenericPages;
using XenAPI;

namespace XenAdmin.Wizards.CrossPoolMigrateWizard
{

    public class CrossPoolMigrateDelayLoadingComboBoxItem : DelayLoadingOptionComboBoxItem
    {
        private readonly Host preSelectedHost;
        private readonly List<VM> preSelectedVMs;
        private  Queue<ReasoningFilter> filters;

        /// <summary>
        /// Instantiate a delay loading combo box item for cross pool migrate
        /// </summary>
        /// <param name="itemAddedToComboBox">Item being added to the list</param>
        /// <param name="preSelectedHost">Host that was preselected by user prior to loading this item</param>
        /// <param name="preSelectedVMs">VMs selected prior to loading this item</param>
        public CrossPoolMigrateDelayLoadingComboBoxItem(IXenObject itemAddedToComboBox, Host preSelectedHost, List<VM> preSelectedVMs)
            : base(itemAddedToComboBox)
        {
            this.preSelectedHost = preSelectedHost;
            this.preSelectedVMs = preSelectedVMs;
        }

        /// <summary>
        /// FIFO of filters
        /// </summary>
        /// <returns></returns>
        private void BuildFilterList()
        {
            filters = new Queue<ReasoningFilter>();
            filters.Enqueue(new CrossPoolMigrateVersionFilter(Item));
            filters.Enqueue(new ResidentHostIsSameAsSelectionFilter(Item, preSelectedVMs));
            filters.Enqueue(new CrossPoolMigrateCanMigrateFilter(Item, preSelectedVMs));
            filters.Enqueue(new WlbEnabledFilter(Item, preSelectedVMs));
        }

        protected override string FetchFailureReason()
        {
            BuildFilterList();

            foreach (ReasoningFilter filter in filters)
            {
                if (filter.FailureFound)
                {
                    return filter.Reason;
                }  
            }

            return String.Empty;
        }
    }
}
