using System;
using System.Collections.Generic;
using System.Linq;

using Server.Engines.CannedEvil;
using Server.Engines.MiniChamps;
using Server.Mobiles;

namespace Server.Custom.Bridge
{
    /// <summary>
    ///     The champion-spawn stream. Like the streams in <see cref="BridgeSweeps"/>, this is polled:
    ///     none of the three champion families expose an EventSink, so their whole lifecycle lives
    ///     inside a per-second SliceTimer and is invisible to a subscriber. Instead we enumerate them
    ///     each tick, fold each to a small record, and emit `champ.update` only when that record
    ///     changes. A 5-10s sweep is well within the site's tolerance and the world holds only a
    ///     handful of spawns, so the pass is trivially cheap.
    ///
    ///     Three families, distinguished by the `category` field:
    ///       champion - ChampionSpawn: the classic Felucca-style altar (type/level/kills/boss/cooldown)
    ///       mini     - MiniChamp:     the TerMur mini-champ controller (type/level, auto-restarts)
    ///       sea      - BaseSeaChampion: a High Seas world boss Mobile, alive only while summoned
    ///
    ///     Status folds public fields into three values (no core patch needed):
    ///       active   - running / alive
    ///       cooldown - stopped but a restart is pending (ChampionSpawn: RestartTime ahead; MiniChamp:
    ///                  inactive, since it always re-arms a restart)
    ///       dormant  - stopped with nothing scheduled (ChampionSpawn only; a GM must turn it on)
    ///
    ///     The sidecar keeps the latest record per serial as a live board. A permanent controller's
    ///     row lives as long as the item; a transient sea boss is removed with `champ.remove` when it
    ///     dies or despawns. A (re)connection clears the diff cache (see OnConnected) so the next
    ///     sweep re-emits every spawn in full, rebuilding a sidecar that restarted on its own.
    /// </summary>
    public static class BridgeChamps
    {
        private static Timer _timer;

        // Last-emitted signature per tracked serial. A serial absent from this map has never been
        // emitted (or the cache was cleared on reconnect), so its next sweep counts as a change.
        // Item and Mobile serials occupy disjoint ranges, so one map safely spans all three families.
        private static readonly Dictionary<Serial, string> _last = new Dictionary<Serial, string>();

        // Protocol 6. Which spawn a live champion belongs to, refreshed by the sweep. The kill itself
        // is detected by TYPE (see OnCreatureDeath), so this map only ever supplies CONTEXT — which
        // altar, at what level. A boss that popped and died inside one sweep interval is still
        // reported; it simply arrives without its spawn.
        private static readonly Dictionary<Serial, Serial> _bossOf = new Dictionary<Serial, Serial>();

        // How many damage entries a kill reports. Deep enough that a real champion fight's meaningful
        // contributors are all present, shallow enough that the frame stays one line on the wire.
        private const int MaxDamagers = 20;

        private static long _sweeps, _emitted, _removed, _bossKills;

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

            EventSink.ServerStarted += OnServerStarted;
        }

        private static void OnServerStarted()
        {
            // Re-emit the full board whenever the sidecar (re)connects, so a sidecar that restarted
            // independently of the shard rebuilds its state within one sweep.
            BridgeLink.Connected_Core += OnConnected;

            // Protocol 6. A boss defeat was previously only INFERABLE — champ.update going bossUp
            // true then false, correlated against a mob.killed nearby — and that inference is both
            // fragile and silent about who did the work. It is a real moment in a shard's week and
            // an event's phase condition wants to name it, so it becomes a kind of its own.
            EventSink.CreatureDeath += OnCreatureDeath;

            Rearm();
        }

        private static void OnConnected()
        {
            _last.Clear();

            // _bossOf is deliberately NOT cleared. It is a fact about the world, not a diff cache:
            // dropping it on a sidecar reconnect would lose the spawn attribution for a boss that is
            // up right now, and it refills from the sweep only if that boss's record happens to
            // change again before it dies.
        }

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

            _timer = Timer.DelayCall(
                TimeSpan.FromSeconds(BridgeConfig.ChampSweepSeconds),
                TimeSpan.FromSeconds(BridgeConfig.ChampSweepSeconds),
                ChampSweep);
        }

        public static void Stop()
        {
            if (_timer != null) { _timer.Stop(); _timer = null; }
        }

        public static string Status()
        {
            return String.Format("champs(sweeps={0} emitted={1} removed={2} tracked={3} bossKills={4} bossesUp={5})",
                _sweeps, _emitted, _removed, _last.Count, _bossKills, _bossOf.Count);
        }

        // ---- champ.boss.killed (Protocol 6) ----

        /// <summary>
        ///     Fires for every creature death on the shard, so the first thing it does is decide
        ///     this is not one. Detection is by TYPE — <c>BaseChampion</c>, which
        ///     <c>BaseSeaChampion</c> derives from, so one check covers both families — with the
        ///     sweep's map used only to name the altar. A boss that popped and died between two
        ///     sweeps is therefore still reported; it simply arrives without a spawn.
        ///
        ///     The damage table is read here and nowhere else, because it exists here and nowhere
        ///     else: ServUO discards a creature's damage entries with the creature, and the shard is
        ///     the only party that ever sees them. Entries are reported whether or not ServUO
        ///     considers them expired — expiry governs LOOTING RIGHTS, and someone who fought the
        ///     first two thirds of a champion fight and then died took part in it regardless of what
        ///     they are owed from the corpse.
        /// </summary>
        private static void OnCreatureDeath(CreatureDeathEventArgs e)
        {
            try
            {
                var boss = e.Creature;

                if (boss == null)
                    return;

                Serial spawnSerial;
                bool attributed = _bossOf.TryGetValue(boss.Serial, out spawnSerial);

                if (!(boss is BaseChampion) && !attributed)
                    return;

                _bossOf.Remove(boss.Serial);
                _bossKills++;

                var spawn = attributed ? World.FindItem(spawnSerial) as ChampionSpawn : null;
                var name = String.IsNullOrEmpty(boss.Name) ? boss.GetType().Name : boss.Name;

                var sb = BridgeJson.Begin("champ.boss.killed")
                    .Str("category", boss is BaseSeaChampion ? "sea" : "champion")
                    .Ser("bossSerial", boss.Serial)
                    .Str("boss", name)
                    .Str("bossType", boss.GetType().Name)
                    .Str("map", boss.Map == null ? null : boss.Map.Name)
                    .Num("x", boss.X).Num("y", boss.Y).Num("z", boss.Z);

                // The altar's own record, when the kill could be attributed to one. `serial` is the
                // SPAWN here, matching champ.update, so a consumer can join the two without a rule
                // about which of two serials on the frame means what.
                if (spawn != null)
                {
                    sb.Ser("serial", spawn.Serial)
                      .Str("type", spawn.Type.ToString())
                      .Num("level", spawn.Level);
                }

                // A named region is what a phase condition can actually match on ("the boss in
                // Yew"); coordinates are not. Emitted alongside the coordinates rather than
                // instead, because large stretches of the map belong to no named region at all.
                //
                // **The innermost region here is ANONYMOUS, and the rig is the only thing that was
                // ever going to say so.** A champion killed in the middle of Britain produced a
                // frame with no region at all, because an active `ChampionSpawn` registers a
                // `ChampionSpawnRegion` over its own spawn area — constructed with a null name and
                // with the town region as its PARENT (`ChampionSpawn.cs`, its constructor). So the
                // most specific region containing a champion boss is, by construction, the one
                // region on the map guaranteed to have no name.
                //
                // It also explains why this looked fine for twenty seconds: region registration is
                // deferred, so a lookup immediately after the altar is placed still answers
                // "Britain" and one at the kill does not. A first read at spawn time would have
                // confirmed a bug into the design.
                //
                // Walking to the nearest NAMED ancestor is the general answer rather than a special
                // case for champions: a house region, a dungeon sub-region and a guarded-zone
                // overlay are all anonymous children of somewhere a player would name.
                var region = NamedRegionAt(boss.Location, boss.Map);

                if (region != null)
                    sb.Str("region", region);

                if (e.Killer != null)
                    sb.Actor("killer", e.Killer);

                sb.Damagers("damagers", TopDamagers(boss), MaxDamagers);

                BridgeLink.Emit(sb.End());
            }
            catch (Exception ex)
            {
                // A death handler must never be the thing that breaks a death.
                Console.WriteLine("[Bridge] champ.boss.killed threw: {0}", ex.Message);
            }
        }

        /// <summary>
        ///     Player damage against this creature, highest first. Totals are summed per damager
        ///     rather than trusted to be one entry each: ServUO's own registration folds repeat
        ///     damage into an existing entry, but an entry that expired and was re-created leaves
        ///     two, and a table that listed the same player twice would be read as two participants.
        /// </summary>
        /// <summary>
        ///     The nearest NAMED region containing a point, walking outward from the most specific
        ///     one, or null when nothing on the way out has a name.
        ///
        ///     Null rather than "" so the caller can leave the field off the frame entirely: a
        ///     consumer reading `region: ""` cannot tell "outdoors, nowhere in particular" from
        ///     "somewhere, but the shard would not say", and only one of those is true here.
        ///
        ///     The map's own default region terminates the walk with its parentless empty name, so
        ///     a point in open countryside answers null without a special case.
        /// </summary>
        private static string NamedRegionAt(Point3D p, Map map)
        {
            if (map == null)
                return null;

            for (var region = Region.Find(p, map); region != null; region = region.Parent)
            {
                if (!String.IsNullOrEmpty(region.Name))
                    return region.Name;
            }

            return null;
        }

        private static List<KeyValuePair<Mobile, int>> TopDamagers(Mobile boss)
        {
            var totals = new Dictionary<Mobile, int>();

            var entries = boss.DamageEntries;

            if (entries != null)
            {
                for (int i = 0; i < entries.Count; i++)
                {
                    var de = entries[i];

                    if (de == null || de.Damager == null || de.Damager.Deleted || !de.Damager.Player)
                        continue;

                    int running;
                    totals.TryGetValue(de.Damager, out running);
                    totals[de.Damager] = running + de.DamageGiven;
                }
            }

            var ranked = totals.ToList();
            ranked.Sort((a, b) => b.Value.CompareTo(a.Value));

            return ranked;
        }

        /// <summary>Runs one sweep now. Wired into `[bridge sweepnow`.</summary>
        public static void SweepOnce()
        {
            ChampSweep();
        }

        private static void ChampSweep()
        {
            try
            {
                _sweeps++;

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

                var seen = new HashSet<Serial>();

                foreach (var s in World.Items.Values.OfType<ChampionSpawn>())
                {
                    if (s.Deleted)
                        continue;

                    // Protocol 6. Remember which altar a live champion belongs to so its death can
                    // name one. Recorded here rather than looked up at death because the lookup
                    // would be a scan of World.Items on every creature death on the shard.
                    var champion = s.Champion;

                    if (champion != null && !champion.Deleted)
                        _bossOf[champion.Serial] = s.Serial;

                    Track(seen, s.Serial, SigChampion(s), WriteChampion(s));
                }

                foreach (var s in World.Items.Values.OfType<MiniChamp>())
                {
                    if (s.Deleted)
                        continue;
                    Track(seen, s.Serial, SigMini(s), WriteMini(s));
                }

                foreach (var b in World.Mobiles.Values.OfType<BaseSeaChampion>())
                {
                    if (b.Deleted || !b.Alive)
                        continue;
                    Track(seen, b.Serial, SigSea(b), WriteSea(b));
                }

                // Anything tracked last sweep but not seen now has gone away (a controller deleted, a
                // sea boss slain). Tell the sidecar to drop its board row.
                var gone = _last.Keys.Where(k => !seen.Contains(k)).ToList();
                foreach (var serial in gone)
                {
                    _last.Remove(serial);
                    BridgeLink.Emit(BridgeJson.Begin("champ.remove").Ser("serial", serial).End());
                    _removed++;
                }

                // A defeated champion's attribution is consumed by OnCreatureDeath, but one deleted
                // by a GM or lost to a world reload never dies, so the map is swept too. Cheap: it
                // holds at most one entry per altar with a boss currently up.
                if (_bossOf.Count > 0)
                {
                    var vanished = _bossOf.Keys
                        .Where(k => { var m = World.FindMobile(k); return m == null || m.Deleted; })
                        .ToList();

                    foreach (var k in vanished)
                        _bossOf.Remove(k);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] champ sweep threw: {0}", ex.Message);
            }
        }

        /// <summary>Records a spawn as seen and emits it only if its signature changed since last sweep.</summary>
        private static void Track(HashSet<Serial> seen, Serial serial, string sig, string line)
        {
            seen.Add(serial);

            string prior;
            if (_last.TryGetValue(serial, out prior) && prior == sig)
                return; // unchanged since last emit

            _last[serial] = sig;
            BridgeLink.Emit(line);
            _emitted++;
        }

        // ---- ChampionSpawn (classic) ----

        private static string StatusOf(ChampionSpawn s)
        {
            if (s.Active)
                return "active";
            if (s.RestartTime > DateTime.UtcNow)
                return "cooldown";
            return "dormant";
        }

        // The volatile fields that define a meaningful change. Kept in sync with WriteChampion so the
        // site never misses a level, a kill-count tick, a boss pop, or a status/cooldown transition.
        private static string SigChampion(ChampionSpawn s)
        {
            return String.Concat(
                "champion|", StatusOf(s), "|",
                s.Level.ToString(), "|",
                s.Kills.ToString(), "|",
                (s.Champion != null && !s.Champion.Deleted) ? "1" : "0", "|",
                s.RestartTime.Ticks.ToString(), "|",
                s.ExpireTime.Ticks.ToString());
        }

        private static string WriteChampion(ChampionSpawn s)
        {
            var status = StatusOf(s);
            var bossUp = s.Champion != null && !s.Champion.Deleted;

            // Prefer a staff-set display name, then the group, then the spawn type.
            string name = !String.IsNullOrEmpty(s.SpawnName) ? s.SpawnName
                        : !String.IsNullOrEmpty(s.GroupName) ? s.GroupName
                        : s.Type.ToString();

            var sb = BridgeJson.Begin("champ.update")
                .Ser("serial", s.Serial)
                .Str("category", "champion")
                .Str("type", s.Type.ToString())
                .Str("name", name)
                .Str("status", status)
                .Bool("active", s.Active)
                .Num("level", s.Level)
                .Num("rank", s.Rank)
                .Num("kills", s.Kills)
                .Num("maxKills", s.MaxKills)
                .Bool("bossUp", bossUp)
                .Bool("autoRestart", s.AutoRestart)
                .Str("map", s.Map == null ? null : s.Map.Name)
                .Num("x", s.X).Num("y", s.Y).Num("z", s.Z);

            if (bossUp)
                sb.Str("boss", String.IsNullOrEmpty(s.Champion.Name) ? s.Champion.GetType().Name : s.Champion.Name);

            // Cooldown ETA: when the spawn will auto-restart. Only meaningful while on cooldown.
            if (status == "cooldown")
                sb.Str("restartAt", s.RestartTime.ToUniversalTime().ToString("o"));

            // Level-expiry ETA: when the current level times out if kills stall. Only while active.
            if (s.Active)
                sb.Str("expireAt", s.ExpireTime.ToUniversalTime().ToString("o"));

            return sb.End();
        }

        // ---- MiniChamp (TerMur mini-champs) ----

        // MiniChamp exposes no kills, no boss handle, and no restart-time getter. When inactive it has
        // always re-armed a restart, so inactive folds to "cooldown" (there is no dormant state and no
        // ETA to report).
        private static string SigMini(MiniChamp s)
        {
            return String.Concat(
                "mini|", (s.Active ? "active" : "cooldown"), "|", s.Level.ToString());
        }

        private static string WriteMini(MiniChamp s)
        {
            var status = s.Active ? "active" : "cooldown";
            var info = MiniChampInfo.GetInfo(s.Type);

            var sb = BridgeJson.Begin("champ.update")
                .Ser("serial", s.Serial)
                .Str("category", "mini")
                .Str("type", s.Type.ToString())
                .Str("name", s.Type.ToString())
                .Str("status", status)
                .Bool("active", s.Active)
                .Num("level", s.Level)
                .Bool("bossUp", false)
                .Bool("autoRestart", true)
                .Str("map", s.Map == null ? null : s.Map.Name)
                .Num("x", s.X).Num("y", s.Y).Num("z", s.Z);

            if (info != null)
                sb.Num("maxLevel", info.MaxLevel);

            return sb.End();
        }

        // ---- BaseSeaChampion (High Seas world boss) ----

        // A sea champion is a Mobile, not a controller: it exists only while summoned and alive, so it
        // is always "active" on the board and leaves via champ.remove when slain. Position and health
        // are tracked so the board can show a live "world boss here, N% hp".
        private static string SigSea(BaseSeaChampion b)
        {
            return String.Concat(
                "sea|", b.Hits.ToString(), "|", b.X.ToString(), "|", b.Y.ToString());
        }

        private static string WriteSea(BaseSeaChampion b)
        {
            string name = String.IsNullOrEmpty(b.Name) ? b.GetType().Name : b.Name;

            return BridgeJson.Begin("champ.update")
                .Ser("serial", b.Serial)
                .Str("category", "sea")
                .Str("type", b.GetType().Name)
                .Str("name", name)
                .Str("status", "active")
                .Bool("active", true)
                .Bool("bossUp", true)
                .Str("boss", name)
                .Num("hits", b.Hits)
                .Num("hitsMax", b.HitsMax)
                .Str("map", b.Map == null ? null : b.Map.Name)
                .Num("x", b.X).Num("y", b.Y).Num("z", b.Z)
                .End();
        }
    }
}