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using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using XenAdmin.Core;
using XenAPI;
using XenAdmin.Dialogs;


namespace XenAdmin.Commands
{
    /// <summary>
    /// The Command for the menu-items displayed for each Host in the start-on, resume-on and migrate sub-menu when WLB isn't enabled.
    /// </summary>
    internal class VMOperationHostCommand : VMOperationCommand
    {
        public delegate Host GetHostForVM(VM vm);

        private readonly static log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        private readonly Dictionary<VM, string> _cantBootReasons = new Dictionary<VM, string>();
        private readonly bool _noneCanBoot = true;
        private readonly string _text;
        private readonly GetHostForVM _getHostForVM;

        public VMOperationHostCommand(IMainWindow mainWindow, IEnumerable<SelectedItem> vms, GetHostForVM getHostForVM, string text, vm_operations operation, Session session)
            : base(mainWindow, vms, operation)
        {
            Util.ThrowIfParameterNull(session, "session");
            Util.ThrowIfParameterNull(getHostForVM, "getHostForVM");
            Util.ThrowIfParameterNull(text, "text");
            _text = text;
            _getHostForVM = getHostForVM;

            foreach (SelectedItem item in vms)
            {
                VM vm = (VM)item.XenObject;

                string reason = GetVmCannotBootOnHostReason(vm, GetHost(vm), session, operation);

                if (reason == null)
                    _noneCanBoot = false;
                else
                    _cantBootReasons[vm] = reason;
            }
        }

        protected sealed override Host GetHost(VM vm)
        {
            return _getHostForVM(vm);
        }

        public override string MenuText
        {
            get
            {
                if (_noneCanBoot)
                {
                    var uniqueReasons = _cantBootReasons.Values.Distinct().ToList();

                    if (uniqueReasons.Count == 1)
                        return string.Format(Messages.MAINWINDOW_CONTEXT_REASON, _text, uniqueReasons[0]);
                }
                return _text;
            }
        }

        public override Image MenuImage
        {
            get
            {
                return Images.StaticImages._000_TreeConnected_h32bit_16;
            }
        }

        protected override bool CanExecute(VM vm)
        {
            return vm != null && !_cantBootReasons.ContainsKey(vm);
        }

        internal static string GetVmCannotBootOnHostReason(VM vm, Host host, Session session, vm_operations operation)
        {
            Host residentHost = vm.Connection.Resolve(vm.resident_on);

            if (host == null)
                return Messages.NO_HOME_SERVER;

            if (vm.power_state == vm_power_state.Running && residentHost != null
                && Helpers.productVersionCompare(Helpers.HostProductVersion(host), Helpers.HostProductVersion(residentHost)) < 0)
            {
                // This will be a migrate menu if powerstate if running
                return Messages.OLDER_THAN_CURRENT_SERVER;
            }
            
            if (vm.power_state == vm_power_state.Running && residentHost != null && host.opaque_ref == residentHost.opaque_ref)
                return Messages.HOST_MENU_CURRENT_SERVER;

            if ((operation == vm_operations.pool_migrate || operation == vm_operations.resume_on) && VmCpuFeaturesIncompatibleWithHost(host, vm))
            {
                return FriendlyErrorNames.VM_INCOMPATIBLE_WITH_THIS_HOST;
            }

            try
            {
                VM.assert_can_boot_here(session, vm.opaque_ref, host.opaque_ref);
            }
            catch (Failure f)
            {
                if (f.ErrorDescription.Count > 2 && f.ErrorDescription[0] == Failure.VM_REQUIRES_SR)
                {
                    SR sr = host.Connection.Resolve((new XenRef<SR>(f.ErrorDescription[2])));

                    if (sr != null && sr.content_type == SR.Content_Type_ISO)
                        return Messages.MIGRATE_PLEASE_EJECT_YOUR_CD;
                }
                return f.ShortMessage;
            }
            catch (Exception e)
            {
                log.ErrorFormat("There was an error calling assert_can_boot_here on host {0}", host.Name());
                log.Error(e, e);
                return Messages.HOST_MENU_UNKNOWN_ERROR;
            }

            return null;
        }

        protected override CommandErrorDialog GetErrorDialogCore(IDictionary<IXenObject, string> cantExecuteReasons)
        {
            return new CommandErrorDialog(ErrorDialogTitle, ErrorDialogText, cantExecuteReasons);
        }

        protected override string GetCantExecuteReasonCore(IXenObject item)
        {
            VM vm = item as VM;
            if (vm != null && _cantBootReasons.ContainsKey(vm))
                return _cantBootReasons[vm];

            return base.GetCantExecuteReasonCore(item);
        }

        public static bool VmCpuFeaturesIncompatibleWithHost(Host targetHost, VM vm)
        {
            // check the CPU feature compatibility for Dundee and higher hosts
            if (!Helpers.DundeeOrGreater(targetHost))
                return false;

            Host home = vm.Home();
            if (home != null && !Helpers.DundeeOrGreater(home))
                return false;

            if (home == null && !Helpers.DundeeOrGreater(vm.Connection))
                return false;

            // only for running or suspended VMs
            if (vm.power_state != vm_power_state.Running && vm.power_state != vm_power_state.Suspended)
                return false;

            if (vm.last_boot_CPU_flags == null || !vm.last_boot_CPU_flags.ContainsKey("vendor") || !vm.last_boot_CPU_flags.ContainsKey("features")
                || targetHost.cpu_info == null || !targetHost.cpu_info.ContainsKey("vendor"))
                return false;

            if (vm.last_boot_CPU_flags["vendor"] != targetHost.cpu_info["vendor"])
                return true;

            if (vm.IsHVM() && targetHost.cpu_info.ContainsKey("features_hvm"))
                return PoolJoinRules.FewerFeatures(targetHost.cpu_info["features_hvm"], vm.last_boot_CPU_flags["features"]);

            if (!vm.IsHVM() && targetHost.cpu_info.ContainsKey("features_pv"))
                return PoolJoinRules.FewerFeatures(targetHost.cpu_info["features_pv"], vm.last_boot_CPU_flags["features"]);

            return false;
        }
    }
}