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 *     following disclaimer. 
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 *     copyright notice, this list of conditions and the 
 *     following disclaimer in the documentation and/or other 
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 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
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using System;
using System.Collections.Generic;
using System.Reflection;
using System.Threading;
using log4net;
using XenAdmin.Wizards.PatchingWizard.PlanActions;
using XenAPI;

namespace XenAdmin.Wizards.RollingUpgradeWizard.PlanActions
{
    class SemiAutomaticBackgroundThread
    {

        private static readonly ILog log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        private Thread _bw;
        private IDictionary<Host, List<PlanAction>> _planActions;
        private PlanAction _revertAction;
        private IEnumerable<Host> _mastersToUpgrade;

        public event EventHandler<ReportHostDoneArgs> ReportHostDone;
        public event EventHandler<ManageSemiAutomaticPlanActionArgs> ManageSemiAutomaticPlanAction;
        public event EventHandler<ReportRunningArgs> ReportRunning;
        public event EventHandler<ReportExceptionArgs> ReportException;
        public event EventHandler<ReportRevertDoneArgs> ReportRevertDone;
        public event EventHandler Completed;

        public SemiAutomaticBackgroundThread(IEnumerable<Host> mastersToUpgrade, IDictionary<Host, List<PlanAction>> planActions, PlanAction revertAction)
        {
            _planActions = planActions;
            _mastersToUpgrade = mastersToUpgrade;
            _revertAction = revertAction;
            _bw = new Thread(BworkerDoWork) { IsBackground = true };
        }

        public void Start()
        {
            _bw.Start();
        }


        private static List<Host> GetAllHosts(IEnumerable<Host> masters)
        {
            var hosts = new List<Host>();
            foreach (var master in masters)
            {
                hosts.Add(master);
                foreach (var host in master.Connection.Cache.Hosts)
                {
                    if (host != master)
                        hosts.Add(host);
                }
            }
            return hosts;
        }

        private static bool CheckMasterIsUpgraded(List<Host> hosts, int i)
        {
            string masterVersion = hosts[i].ProductVersion;
            for (int j = i + 1; j < hosts.Count; j++)
            {
                if (hosts[j].ProductVersion != masterVersion)
                    return true;
                if (hosts[j].IsMaster())
                    break;
            }
            return false;
        }

        private static int SkipSlaves(List<Host> hosts, int i)
        {
            for (int j = i + 1; j < hosts.Count; j++)
            {
                if (hosts[j].IsMaster())
                    break;
                i++;
            }
            return i;
        }

        private void BworkerDoWork()
        {
            Host currentHost = null;
            try
            {

                List<Host> hosts = GetAllHosts(_mastersToUpgrade);

                bool currentMasterFailed = false;
                string poolHigherProductVersion = string.Empty;
                for (int i = 0; i < hosts.Count; i++)
                {
                    if (_cancel)
                        return;
                    //Skip hosts already upgraded
                    var host=currentHost = hosts[i];
                    if (host.IsMaster())
                    {
                        poolHigherProductVersion = host.ProductVersion;
                        if (CheckMasterIsUpgraded(hosts, i))
                        {
                            log.Debug(string.Format("Skipping master '{0}' because it is upgraded", host.Name));
                            continue;
                        }
                    }
                    else if (host.ProductVersion == poolHigherProductVersion)
                    {
                        log.Debug(string.Format("Skipping host '{0}' because it is upgraded", host.Name));
                        continue;
                    }
                    log.Debug(string.Format("Starting to upgrade host '{0}'", host.Name));
                    //Add subtasks for the current host
                    bool allActionsDone = true;
                    foreach (var planAction in _planActions[host])
                    {
                        //if the wizard has been cancelled, skip this action, unless it is a BringBabiesBackAction
                        if (_cancel && !(planAction is BringBabiesBackAction)) 
                            continue;

                        PlanAction action = planAction;
                        ReportRunning.Raise(this, () => new ReportRunningArgs(action, host));
                        try
                        {
                            if (planAction is UpgradeManualHostPlanAction)
                            {
                                var upgradeAction = (UpgradeManualHostPlanAction)planAction;
                                ManageSemiAutomaticPlanAction.Raise(this, () => new ManageSemiAutomaticPlanActionArgs(upgradeAction));
                                if (host.IsMaster())
                                    poolHigherProductVersion = upgradeAction.Host.ProductVersion;
                            }
                            else
                                planAction.Run();

                        }
                        catch (Exception excep)
                        {
                            log.Error(string.Format("Exception in host '{0}' while it was upgraded", host.Name), excep);
                            PlanAction action1 = planAction;
                            ReportException.Raise(this, () => new ReportExceptionArgs(excep, action1, host));
                            if (host.IsMaster())
                                currentMasterFailed = true;
                            allActionsDone = false;
                            break;
                        }
                    }

                    if (allActionsDone)
                    {
                        ReportHostDone.Raise(this, () => new ReportHostDoneArgs(host));
                    }

                    //Skip slaves if master failed
                    if (currentMasterFailed)
                    {
                        i = SkipSlaves(hosts, i);
                    }
                }


            }
            catch (Exception excep)
            {
                log.Error("Upgrade thread error: ", excep);
            }
            finally
            {
                //Revert resolved prechecks
                try
                {
                    log.Debug("Reverting prechecks");
                    ReportRunning.Raise(this, () => new ReportRunningArgs(_revertAction, currentHost));
                    _revertAction.Run();
                    ReportRevertDone.Raise(this, () => new ReportRevertDoneArgs(_revertAction));
                }
                catch (Exception excep)
                {
                    log.Error("Exception reverting prechecks", excep);
                    ReportException.Raise(this, () => new ReportExceptionArgs(excep, _revertAction, currentHost));
                }

                Completed.Raise(this);
            }

        }

        private volatile bool _cancel = false;
        internal void Cancel()
        {
            _cancel = true;
        }
    }

    internal class ReportRevertDoneArgs : EventArgs
    {

        public ReportRevertDoneArgs(PlanAction planAction)
        {
            PlanAction = planAction;
        }

        public PlanAction PlanAction { get; private set; }
    }

    internal class ReportExceptionArgs : EventArgs
    {
        public ReportExceptionArgs(Exception excep, PlanAction action, Host host)
        {
            Exception = excep;
            Action = action;
            Host = host;
        }

        public Exception Exception { get; private set; }
        public PlanAction Action { get; private set; }
        public Host Host { get; private set; }
    }

    internal class ReportRunningArgs : EventArgs
    {

        public ReportRunningArgs(PlanAction action, Host host)
        {
            Host = host;
            Action = action;
        }

        public Host Host { get; private set; }
        public PlanAction Action { get; private set; }
    }


    internal class ManageSemiAutomaticPlanActionArgs : EventArgs
    {
        public ManageSemiAutomaticPlanActionArgs(UpgradeManualHostPlanAction action)
        {
            Action = action;
        }
        public UpgradeManualHostPlanAction Action { get; private set; }
    }

    internal class ReportHostDoneArgs : EventArgs
    {
        public ReportHostDoneArgs(Host host)
        {
            Host = host;
        }
        public Host Host { get; private set; }
    }
}