using System;
using System.Collections.Generic;
using System.Text;

using Server.Accounting;
using Server.Mobiles;
using Server.Multis;

namespace Server.Custom.Bridge
{
    /// <summary>
    ///     The three polled streams, for state that has no EventSink: player vitals, house decay,
    ///     and money supply. All three run on the Core thread via repeating Timers, and the
    ///     measured cost (https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/link/PLAN.md §1) is why they can: at the seeded scale a full pass of all
    ///     three is well under a millisecond.
    ///
    ///     Timers do not fire during a world save (Timer.cs:322), so a sweep that would have landed
    ///     mid-save simply happens a few seconds later. That is fine for all three.
    /// </summary>
    public static class BridgeSweeps
    {
        private static Timer _vitals, _decay, _economy;

        // Last-known decay level per house. In memory, rebuilt from a silent baseline on
        // ServerStarted, so a restart does not re-announce every house's current stage.
        private static readonly Dictionary<Serial, DecayLevel> _decayState =
            new Dictionary<Serial, DecayLevel>();

        private static bool _baselined;

        private static long _vitalsSweeps, _vitalsEmitted, _decaySweeps, _decayTransitions, _economySweeps;

        public static void Initialize()
        {
            if (!BridgeConfig.Enabled)
                return;

            EventSink.ServerStarted += OnServerStarted;
        }

        private static void OnServerStarted()
        {
            BaselineDecay();
            Rearm();
        }

        /// <summary>Stops and recreates the timers from current config. Called by `[bridge reload`.</summary>
        public static void Rearm()
        {
            Stop();

            _vitals = Timer.DelayCall(
                TimeSpan.FromSeconds(BridgeConfig.StatSweepSeconds),
                TimeSpan.FromSeconds(BridgeConfig.StatSweepSeconds),
                VitalsSweep);

            _decay = Timer.DelayCall(
                TimeSpan.FromSeconds(BridgeConfig.DecaySweepSeconds),
                TimeSpan.FromSeconds(BridgeConfig.DecaySweepSeconds),
                DecaySweep);

            _economy = Timer.DelayCall(
                TimeSpan.FromSeconds(BridgeConfig.EconomySweepSeconds),
                TimeSpan.FromSeconds(BridgeConfig.EconomySweepSeconds),
                EconomySweep);
        }

        public static void Stop()
        {
            if (_vitals != null) { _vitals.Stop(); _vitals = null; }
            if (_decay != null) { _decay.Stop(); _decay = null; }
            if (_economy != null) { _economy.Stop(); _economy = null; }
        }

        public static string Status()
        {
            return String.Format(
                "vitals(sweeps={0} emitted={1}) decay(sweeps={2} transitions={3} tracked={4}) economy(sweeps={5})",
                _vitalsSweeps, _vitalsEmitted, _decaySweeps, _decayTransitions, _decayState.Count, _economySweeps);
        }

        // ---- vitals ----

        /// <summary>
        ///     Online players only. Vitals are small and volatile; the sidecar diffs successive
        ///     snapshots and forwards only changes. Offline characters do not move, so there is
        ///     nothing to sweep — their state is served on demand as a full profile instead.
        /// </summary>
        private static void VitalsSweep()
        {
            try
            {
                _vitalsSweeps++;

                if (!BridgeLink.Connected)
                    return; // nothing is listening; do not fill the queue with perishable snapshots

                foreach (var m in World.Mobiles.Values)
                {
                    var pm = m as PlayerMobile;

                    if (pm == null || pm.NetState == null || pm.Deleted)
                        continue;

                    BridgeLink.Emit(WriteVitals(pm));
                    _vitalsEmitted++;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] vitals sweep threw: {0}", ex.Message);
            }
        }

        private static string WriteVitals(PlayerMobile m)
        {
            return BridgeJson.Begin("char.vitals")
                .Ser("serial", m.Serial)
                .Num("hits", m.Hits).Num("hitsMax", m.HitsMax)
                .Num("mana", m.Mana).Num("manaMax", m.ManaMax)
                .Num("stam", m.Stam).Num("stamMax", m.StamMax)
                .Num("str", m.Str).Num("dex", m.Dex).Num("int", m.Int)
                .Str("map", m.Map == null ? null : m.Map.Name)
                .Num("x", m.X).Num("y", m.Y)
                .End();
        }

        // ---- house decay ----

        /// <summary>
        ///     Populates the last-known level for every house without emitting. Without this, the
        ///     first sweep after a restart would report every house as a fresh transition.
        /// </summary>
        private static void BaselineDecay()
        {
            try
            {
                _decayState.Clear();

                foreach (var house in BaseHouse.AllHouses)
                {
                    if (house == null || house.Deleted)
                        continue;

                    _decayState[house.Serial] = house.DecayLevel;
                }

                _baselined = true;
                Console.WriteLine("[Bridge] decay baseline: {0} houses", _decayState.Count);
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] decay baseline threw: {0}", ex.Message);
            }
        }

        private static void DecaySweep()
        {
            try
            {
                _decaySweeps++;

                if (!_baselined)
                    BaselineDecay();

                foreach (var house in BaseHouse.AllHouses)
                {
                    if (house == null || house.Deleted)
                        continue;

                    var level = house.DecayLevel; // computed getter — read once
                    var serial = house.Serial;

                    DecayLevel prior;
                    bool known = _decayState.TryGetValue(serial, out prior);

                    if (known && prior == level)
                        continue;

                    _decayState[serial] = level;

                    if (!known)
                        continue; // a house that appeared since baseline; record, do not announce

                    _decayTransitions++;

                    if (BridgeLink.Connected)
                        BridgeLink.Emit(WriteDecay(house, prior, level));
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] decay sweep threw: {0}", ex.Message);
            }
        }

        private static string WriteDecay(BaseHouse house, DecayLevel from, DecayLevel to)
        {
            var sb = BridgeJson.Begin("house.decay")
                .Ser("serial", house.Serial)
                .Str("from", from.ToString())
                .Str("to", to.ToString())
                .Str("map", house.Map == null ? null : house.Map.Name)
                .Num("x", house.X).Num("y", house.Y).Num("z", house.Z);

            var region = house.Region;
            if (region != null)
                sb.Str("region", region.Name);

            var sign = house.Sign;
            if (sign != null)
                sb.Str("name", sign.GetName());

            var owner = house.Owner;
            if (owner != null)
            {
                sb.Ser("ownerSerial", owner.Serial);
                sb.Str("ownerName", owner.Name);
                var acct = owner.Account as Account;
                if (acct != null)
                    sb.Str("ownerAcct", acct.Username);
            }

            AppendDecaySchedule(sb, house, to);

            // Where a player would physically stand to see it.
            var ban = house.BanLocation;
            sb.Append(",\"ban\":{\"x\":").Append(ban.X)
              .Append(",\"y\":").Append(ban.Y)
              .Append(",\"z\":").Append(ban.Z).Append('}');

            sb.Str("builtOn", house.BuiltOn.ToUniversalTime().ToString("o"));
            sb.Str("lastRefreshed", house.LastRefreshed.ToUniversalTime().ToString("o"));

            return sb.End();
        }

        /// <summary>
        ///     Protocol 5. The three scheduling fields, and the reason they are not all always present.
        ///
        ///     ServUO has two decay implementations and they differ in how KNOWABLE the future is:
        ///
        ///       * Dynamic decay (DynamicDecay.Enabled, i.e. Core.ML) draws each stage's duration at
        ///         RANDOM when the stage is entered (BaseHouse.SetDynamicDecay ->
        ///         DynamicDecay.GetRandomDuration). So NextDecayStage is exact for the NEXT transition
        ///         and nothing beyond it is known at all. Collapse becomes exact only once the house is
        ///         already at IDOC, because then the next transition IS the collapse.
        ///       * Static decay (GetOldDecayLevel) is a pure function of LastRefreshed and DecayPeriod,
        ///         so collapse is exact at EVERY stage -- there is no randomness to wait out.
        ///
        ///     Emitting estimatedCollapse from a dynamic-decay house at, say, Fairly would therefore be
        ///     publishing a guess as a fact, which on the website's side becomes a dated promise in a
        ///     player's mail. It is omitted rather than approximated: the website's `required: false`
        ///     declaration already permits its absence, and an absent field is honest where a wrong
        ///     date is not.
        /// </summary>
        private static void AppendDecaySchedule(StringBuilder sb, BaseHouse house, DecayLevel to)
        {
            // ONE nested object rather than four sibling keys, for the same reason vendor.listing
            // nests `location`: the website's visibility projection matches literal JSON keys, so a
            // nested group is one admin rule that can hide the whole schedule, where four flat keys
            // would be four rules that drift apart.
            sb.Append(",\"schedule\":{");

            // The stage clock. Only dynamic decay keeps one; static decay leaves it at MinValue.
            bool dynamic = DynamicDecay.Enabled;
            var next = house.NextDecayStage;

            sb.Append("\"dynamicDecay\":").Append(dynamic ? "true" : "false");

            if (dynamic && next > DateTime.MinValue)
                sb.Str("nextStage", next.ToUniversalTime().ToString("o"));

            // Total seconds from a full refresh to collapse. Constant per house type, but it is what
            // lets a reader turn lastRefreshed into a percentage without knowing ServUO's tables.
            var period = house.DecayPeriod;
            if (period > TimeSpan.Zero)
                sb.Num("decayPeriodSec", (long)period.TotalSeconds);

            DateTime collapse;
            bool knowable = true;

            if (!dynamic)
                collapse = house.LastRefreshed.ToUniversalTime() + period;
            else if (to == DecayLevel.IDOC && next > DateTime.MinValue)
                collapse = next.ToUniversalTime();
            else
            {
                collapse = DateTime.MinValue;
                knowable = false;
            }

            if (knowable)
                sb.Str("estimatedCollapse", collapse.ToString("o"));

            sb.Append('}');
        }

        // ---- economy supply ----

        /// <summary>
        ///     Money supply = the sum of every account's currency, as a periodic snapshot. This is
        ///     the level; AccountGoldChange and the vendor events are the flow. The sidecar keeps
        ///     both.
        /// </summary>
        private static void EconomySweep()
        {
            try
            {
                _economySweeps++;

                if (!BridgeLink.Connected)
                    return;

                double totalCurrency = 0;
                int accounts = 0;

                foreach (Account a in Accounting.Accounts.GetAccounts())
                {
                    totalCurrency += a.TotalCurrency;
                    accounts++;
                }

                BridgeLink.Emit(BridgeJson.Begin("economy.supply")
                    .Num("accounts", accounts)
                    .Num("gold", (long)(totalCurrency * Account.CurrencyThreshold))
                    .End());
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] economy sweep threw: {0}", ex.Message);
            }
        }

        /// <summary>Runs each sweep once, now. For `[bridge sweepnow`.</summary>
        public static void SweepOnce()
        {
            VitalsSweep();
            DecaySweep();
            EconomySweep();
        }
    }
}