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using System;
using System.Collections.Generic;
using XenAdmin.Diagnostics.Problems.PoolProblem;
using XenAdmin.Network;
using XenAPI;
using XenAdmin.Diagnostics.Problems;
using XenAdmin.Core;
using XenAdmin.Diagnostics.Problems.VMProblem;
using XenAdmin.Diagnostics.Problems.HostProblem;

namespace XenAdmin.Diagnostics.Checks
{
    class AssertCanEvacuateCheck : HostPostLivenessCheck
    {
        private static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        private readonly Dictionary<string, livepatch_status> livePatchCodesByHost;

        public AssertCanEvacuateCheck(Host host, Dictionary<string, livepatch_status> livePatchCodesByHost)
            : base(host)
        {
            this.livePatchCodesByHost = livePatchCodesByHost;
        }

        public AssertCanEvacuateCheck(Host host)
            : base(host)
        {
        }

        protected List<Problem> CheckHost()
        {
            // when livepatching is available, no restart is expected, so this check is not needed
            if (livePatchCodesByHost != null && livePatchCodesByHost.ContainsKey(Host.uuid) && livePatchCodesByHost[Host.uuid] == livepatch_status.ok_livepatch_complete)
            {
                log.DebugFormat("Check not needed for host {0}, because pool_patch.Precheck() returned PATCH_PRECHECK_LIVEPATCH_COMPLETE for update.", Host);
                return new List<Problem>();
            }

            var problems = new List<Problem>();

            var restrictMigration = Helpers.FeatureForbidden(Host.Connection, Host.RestrictIntraPoolMigrate);

            var VMsWithProblems = new List<string>();
            var residentVMs = Host.Connection.ResolveAll(Host.resident_VMs);
            foreach (var residentVM in residentVMs)
            {
                if (residentVM.GetAutoPowerOn())
                {
                    problems.Add(new AutoStartEnabled(this, residentVM));
                    VMsWithProblems.Add(residentVM.opaque_ref);
                    continue;
                }

                SR sr = residentVM.FindVMCDROMSR();
                if (sr != null && sr.IsToolsSR())
                {
                    problems.Add(new ToolsCD(this, residentVM));
                    VMsWithProblems.Add(residentVM.opaque_ref);
                }
                else if (sr != null && sr.content_type == SR.Content_Type_ISO && (!sr.shared || Properties.Settings.Default.EjectSharedIsoOnUpdate))
                {
                    problems.Add(new LocalCD(this, residentVM));
                    VMsWithProblems.Add(residentVM.opaque_ref);
                }

                if (restrictMigration && residentVM.IsRealVm() && !VMsWithProblems.Contains(residentVM.opaque_ref))
                {
                    problems.Add(new CannotMigrateVM(this, residentVM, CannotMigrateVM.CannotMigrateVMReason.LicenseRestriction));
                    VMsWithProblems.Add(residentVM.opaque_ref);
                }
            }

            // if VM migration is restricted, then we are already forcing all VMs to be shutdown/suspended, so there is not need to call get_vms_which_prevent_evacuation
            if (restrictMigration)
                return problems;

            Session session = Host.Connection.DuplicateSession();
            Dictionary<XenRef<VM>, String[]> vms =
                Host.get_vms_which_prevent_evacuation(session, Host.opaque_ref);

            foreach (KeyValuePair<XenRef<VM>, String[]> kvp in vms)
            {
                String[] exception = kvp.Value;
                XenRef<VM> vmRef = kvp.Key;

                if (VMsWithProblems.Contains(vmRef))
                    continue;

                try
                {
                    Problem p = GetProblem(Host.Connection, vmRef, exception);
                    if (p != null)
                        problems.Add(p);
                }
                catch (Exception e)
                {
                    log.Debug("Didn't recognise reason", e);
                    log.Debug(exception);

                    VM vm = Host.Connection.Resolve(kvp.Key);

                    if (vm != null)
                        problems.Add(new CannotMigrateVM(this, vm));
                }
            }

            return problems;
        }

        private Problem GetProblem(IXenConnection connection, XenRef<VM> vmRef, string[] exception)
        {
            try
            {
                System.Diagnostics.Trace.Assert(exception.Length > 0);

                var vm = connection.Resolve<VM>(vmRef);

                if (vm == null)
                {
                    throw new NullReferenceException(exception[0]);
                }

                switch (exception[0])
                {
                    case Failure.VM_REQUIRES_SR:
                        XenRef<SR> srRef = new XenRef<SR>(exception[2]);
                        SR sr = connection.Resolve<SR>(srRef);

                        if (sr == null)
                            throw new NullReferenceException(Failure.VM_REQUIRES_SR);

                        if (sr.content_type == SR.Content_Type_ISO)
                        {
                            return new LocalCD(this, vm);
                        }
                        else if (!sr.shared)
                        {
                            // Only show the problem if it is really local storage
                            // As the pbd-plug checks will pick up broken storage.
                            return new LocalStorage(this, vm);
                        }

                        return null;

                    case Failure.VM_MISSING_PV_DRIVERS:
                        return new NoPVDrivers(this, vm);

                    case Failure.VM_LACKS_FEATURE:
                        return new CannotMigrateVM(this, vm, GetMoreSpecificReasonForCannotMigrateVm(vm, CannotMigrateVM.CannotMigrateVMReason.CannotMigrateVm));

                    case Failure.VM_LACKS_FEATURE_SUSPEND:
                        return new CannotMigrateVM(this, vm, GetMoreSpecificReasonForCannotMigrateVm(vm, CannotMigrateVM.CannotMigrateVMReason.LacksFeatureSuspend));

                    case Failure.VM_HAS_PCI_ATTACHED:
                        return new CannotMigrateVM(this, vm, GetMoreSpecificReasonForCannotMigrateVm(vm, CannotMigrateVM.CannotMigrateVMReason.HasPCIAttached));

                    case "VM_OLD_PV_DRIVERS":
                        return new PVDriversOutOfDate(this, vm);

                    case Failure.NO_HOSTS_AVAILABLE:
                        //CA-63531: Boston server will come here in case of single host pool or standalone host
                        return new NoHosts(this, vm);

                    case Failure.HOST_NOT_ENOUGH_FREE_MEMORY:
                        Pool pool = Helpers.GetPool(vm.Connection);

                        if (pool == null || pool.Connection.Cache.HostCount == 1)
                        {
                            //CA-63531: Cowley server will come here in case of single host pool or standalone host
                            return new NoHosts(this, vm);
                        }

                        Host host = vm.Connection.Resolve(vm.resident_on);
                        return new NotEnoughMem(this, host);

                    case Failure.VM_REQUIRES_NETWORK:
                        XenRef<XenAPI.Network> netRef = new XenRef<XenAPI.Network>(exception[2]);
                        XenAPI.Network network = connection.Resolve(netRef);

                        if (network == null)
                            throw new NullReferenceException(Failure.VM_REQUIRES_NETWORK);

                        return new VMCannotSeeNetwork(this, vm, network);

                    case Failure.VM_REQUIRES_GPU:
                        return new CannotMigrateVM(this, vm, CannotMigrateVM.CannotMigrateVMReason.CannotMigrateVmNoGpu);
                        
                    case Failure.VM_HAS_VGPU:
                        return new VmHasVgpu(this, vm);

                    case Failure.OTHER_OPERATION_IN_PROGRESS:
                        return new CannotMigrateVM(this, vm, CannotMigrateVM.CannotMigrateVMReason.OperationInProgress);

                    default:
                        throw new NullReferenceException(exception[0]);
                }
            }
            catch (Exception e)
            {
                log.Debug("Exception parsing exception", e);

                throw new Failure(new List<String>(exception));
            }
        }

        private static CannotMigrateVM.CannotMigrateVMReason GetMoreSpecificReasonForCannotMigrateVm(VM vm, CannotMigrateVM.CannotMigrateVMReason reason)
        {
            var gm = vm.Connection.Resolve(vm.guest_metrics);
            var status = vm.GetVirtualizationStatus(out _);

            if (vm.IsWindows())
            {
                if (gm != null && !gm.PV_drivers_detected)
                {
                    reason = CannotMigrateVM.CannotMigrateVMReason.CannotMigrateVmNoTools;
                }
            }
            else if (status == VM.VirtualizationStatus.NotInstalled || status.HasFlag(VM.VirtualizationStatus.PvDriversOutOfDate))
            {
                reason = CannotMigrateVM.CannotMigrateVMReason.CannotMigrateVmNoTools;
            }

            return reason;
        }

        // This function only tests certain host-wide conditions.
        // Further per-VM conditions are in CheckHost().
        // See RunAllChecks() for how we combine them.
        protected override Problem RunHostCheck()
        {
            Pool pool = Helpers.GetPool(Host.Connection);

            if (pool == null || (!pool.ha_enabled && !pool.wlb_enabled))
                return null;
            
            return new HaWlbEnabledWarning(this, pool, Host);
        }

        public override List<Problem> RunAllChecks()
        {
            var list = base.RunAllChecks();
            if (list.Count > 0)
                return list;
            else
                return CheckHost();
        }

        public override string Description => Messages.ASSERT_CAN_EVACUATE_CHECK_DESCRIPTION;
    }
}