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using System;
using System.Collections.Generic;
using XenAPI;


namespace XenAdmin.Wlb
{
    /// <summary>
    /// Optimize pool recommendation properties
    /// </summary>
    // WLB: find optId, assume recommendation return string format is ["WLB"; host; optId; recID; reason]
    public enum RecProperties
    {
        /// <summary>
        /// WLB recommendation.
        /// </summary>
        WLB = 0,

        /// <summary>
        /// Recommend moving to host.
        /// </summary>
        ToHost = 1,

        /// <summary>
        /// Optimize VM set ID
        /// </summary>
        OptId = 2,

        /// <summary>
        /// VM recommendation ID
        /// </summary>
        RecId = 3,

        /// <summary>
        /// Recommend moving reason
        /// </summary>
        Reason = 4
    }


    /// <summary>
    /// Tag each ListView row in WLBOptimizePool with one of these, and pass them to row update.
    /// </summary>
    public class WlbOptimizationRecommendation
    {
        public readonly VM vm;
        public readonly string reason;
        public readonly Host fromHost;
        public readonly Host toHost;
        public readonly int recId;
        public readonly int optId;
        public readonly string powerOperation;
        public const string OPTIMIZINGPOOL = "wlb_optimizing_pool";

        /// <summary>
        /// Set optimization vm properties
        /// </summary>
        /// <param name="vm">vm from optimize pool recommendations.</param>
        /// <param name="fromHost">host vm resides on.</param>
        /// <param name="toHost">host to move vm to.</param>
        /// <param name="reason">optimize reason.</param>
        internal WlbOptimizationRecommendation(VM vm, Host fromHost, Host toHost, string reason, int recId, int optId, string powerOperation)
        {
            this.vm = vm;
            this.fromHost = fromHost;
            this.toHost = toHost;
            this.reason = reason;
            this.recId = recId;
            this.optId = optId;
            this.powerOperation = powerOperation;
        }
    }


    public class WlbOptimizationRecommendationCollection : List<WlbOptimizationRecommendation>
    {
        public WlbOptimizationRecommendationCollection(Pool pool, Dictionary<XenRef<VM>, string[]> recommendations)
        {
            LoadSortedRecommendationList(pool, recommendations);
        }

        private void LoadSortedRecommendationList(Pool pool, Dictionary<XenRef<VM>, string[]> recommendations)
        {
            // When there are host powerOn recommendations, the toHost of the recommended move vms are disabled,
            // We use the powerOhHosts list to check if the toHost of the recommended move vms is a powerOnHost when it's disabled 
            List<Host> powerOnHosts = GetAllPowerOnHosts(pool, recommendations);
            bool clearList = false;

            foreach (KeyValuePair<XenRef<VM>, string[]> rec in recommendations)
            {
                if (rec.Value[0].Trim().ToLower() == "wlb")
                {
                    int.TryParse(rec.Value[(int)RecProperties.RecId], out var recId);
                    int.TryParse(rec.Value[(int)RecProperties.OptId], out var optId);

                    VM vm = pool.Connection.Resolve(rec.Key);
                    Host toHost = !vm.is_control_domain ? pool.Connection.Cache.Find_By_Uuid<Host>(rec.Value[(int)RecProperties.ToHost]) : null;
                    Host fromHost = !vm.is_control_domain ? pool.Connection.Resolve(vm.resident_on) : pool.Connection.Cache.Find_By_Uuid<Host>(rec.Value[(int)RecProperties.ToHost]);

                    ParseRecommendationReason(rec.Value[(int)RecProperties.Reason], out var powerOperation, out var resourcedReasonOutput);

                    if ((vm.is_control_domain && fromHost != null)
                        || (vm.power_state == vm_power_state.Running 
                            && toHost != fromHost 
                            && ((powerOnHosts.Count > 0 && toHost != null && !toHost.enabled && powerOnHosts.Contains(toHost)) 
                                || (toHost != null && toHost.enabled))))
                    {

                        WlbOptimizationRecommendation optVmSetting = new WlbOptimizationRecommendation(vm, fromHost, toHost, resourcedReasonOutput, recId, optId, powerOperation);

                        // Clear the recommendation collection if the number of vms on a power off host 
                        // doesn't match the vms in the recommendations

                        if (IsHostPowerOff(vm, powerOperation, fromHost)
                            && !VmsOnPowerOffHostAreInRecommendations(fromHost, recommendations))
                        {
                            clearList = true;
                            break;
                        }

                        if (!vm.is_control_domain || IsHostPowerOnOff(vm, fromHost, powerOperation, recommendations))
                        {
                            Add(optVmSetting);
                        }
                    }
                }
            }

            if (clearList)
            {
                Clear();
            }
            else
            {
                Sort(SortByRecommendationId);
            }
        }

        private List<Host> GetAllPowerOnHosts(Pool pool, Dictionary<XenRef<VM>, string[]> recommendations)
        {
            List<Host> powerOnHosts = new List<Host>();

            foreach (KeyValuePair<XenRef<VM>, string[]> rec in recommendations)
            {
                if (rec.Value[0].Trim().ToLower() == "wlb")
                {
                    VM vm = pool.Connection.Resolve(rec.Key);
                    Host fromHost = !vm.is_control_domain ? pool.Connection.Resolve(vm.resident_on) : pool.Connection.Cache.Find_By_Uuid<Host>(rec.Value[(int)RecProperties.ToHost]);

                    ParseRecommendationReason(rec.Value[(int)RecProperties.Reason], out var powerOperation, out _);

                    if (vm.is_control_domain && fromHost != null && IsHostPowerOn(vm, powerOperation, fromHost))
                    {
                        powerOnHosts.Add(fromHost);
                    }
                }
            }

            return powerOnHosts;
        }

        private void ParseRecommendationReason(string reason, out string powerOperation, out string resourcedReasonOutput)
        {
            powerOperation = null;

            switch (reason.ToUpper())
            {
                case "POWERON":
                    powerOperation = Messages.WLB_OPT_OPERATION_HOST_POWERON;
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_POWERON;
                    break;
                case "POWEROFF":
                    powerOperation = Messages.WLB_OPT_OPERATION_HOST_POWEROFF;
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_POWEROFF;
                    break;
                case "CONSOLIDATE":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_CONSOLIDATE;
                    break;
                case "CPU":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_CPU;
                    break;
                case "DISK":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_DISK;
                    break;
                case "DISKREAD":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_DISKREAD;
                    break;
                case "DISKWRITE":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_DISKWRITE;
                    break;
                case "LOADAVERAGE":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_LOADAVERAGE;
                    break;
                case "MEMORY":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_MEMORY;
                    break;
                case "NETWORK":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_NETWORK;
                    break;
                case "NETWORKREAD":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_NETWORKREAD;
                    break;
                case "NETWORKWRITE":
                    resourcedReasonOutput = Messages.WLB_OPT_REASON_NETWORKWRITE;
                    break;
                case "NONE":
                    resourcedReasonOutput = Messages.NONE_UPPER;
                    break;
                default:
                    resourcedReasonOutput = Messages.UNKNOWN;
                    break;
            }
        }

        private int SortByRecommendationId(WlbOptimizationRecommendation x, WlbOptimizationRecommendation y)
        {
            return x.recId.CompareTo(y.recId);
        }

        private bool IsHostPowerOnOff(VM vm, Host fromHost, string powerOperation, Dictionary<XenRef<VM>, string[]> recommendations)
        {
            if (vm.is_control_domain && fromHost!=null)
            {
                if(IsHostPowerOn(vm, powerOperation, fromHost))
                {
                    return true;
                }

                if(IsHostPowerOff(vm, powerOperation, fromHost) 
                    && VmsOnPowerOffHostAreInRecommendations(fromHost, recommendations))
                {
                    return true;
                }
            }

            return false;
        }

        private bool IsHostPowerOn(VM vm, string powerOperation, Host fromHost)
        {
            if (vm != null && !String.IsNullOrEmpty(powerOperation) && fromHost != null)
            {
                return vm.is_control_domain && (powerOperation == Messages.WLB_OPT_OPERATION_HOST_POWERON) && !fromHost.IsLive();
            }
                
            return false;
        }

        private bool IsHostPowerOff(VM vm, string powerOperation, Host fromHost)
        {
            if (vm != null && !String.IsNullOrEmpty(powerOperation) && fromHost != null)
            {
                return vm.is_control_domain && (powerOperation == Messages.WLB_OPT_OPERATION_HOST_POWEROFF) && fromHost.IsLive();
            }
                
            return false;
        }

        private bool VmsOnPowerOffHostAreInRecommendations(Host fromHost, Dictionary<XenRef<VM>, string[]> recommendations)
        {
            foreach (XenRef<VM> vm in fromHost.resident_VMs)
            {
                if (!recommendations.ContainsKey(vm))
                {
                    return false;
                }
            }

            return true;
        }
    }
}