using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text;

using Server.Mobiles;

namespace Server.Custom.Bridge
{
    /// <summary>
    ///     Protocol 6, part b. The run-scoped participation ledger: who took part in an event, and
    ///     how much.
    ///
    ///     EVENTS.md §G rates participation attribution as the largest remaining piece of new UO
    ///     work, and says why nothing composed out of the existing streams can stand in for it:
    ///     `region.enter` plus `mob.killed` is loosely composable and **not trustworthy enough to
    ///     publish results on**. Nothing scopes a kill or an arrival to a run, nothing separates a
    ///     passer-by from an attendee, and nothing survives a relog. Results and a leaderboard on
    ///     top of that would be a table of confident numbers that were not true.
    ///
    ///     So participation is measured here, where the world is, and reported as one opaque number
    ///     per member. **The plugin computes the score; core stores a decimal it never interprets.**
    ///     That split is what keeps the event engine game-agnostic: "one minute present plus five a
    ///     kill" is a sentence about Ultima Online, and the sentence has to live on the Ultima
    ///     Online side of the seam.
    ///
    ///     ── Keyed by character serial ──────────────────────────────────────────────────────────
    ///
    ///     Which matches `module-uo`'s existing Teams `memberKey` (`teamProvider.model.js`), so one
    ///     module speaks one member vocabulary and a participant can be joined to a roster without a
    ///     translation table. A player who attends on two characters is two members, and that is the
    ///     same answer Teams already gives.
    ///
    ///     ── Persisted in the world save, which is a first ──────────────────────────────────────
    ///
    ///     Nothing in this bridge has ever persisted anything. A ledger has to, because a run spans
    ///     hours and a restart mid-event is an ordinary Tuesday: an in-memory tally would silently
    ///     regress every attendee's score to whatever they earned after the restart. The only ways
    ///     to paper over that from the other side are a high-water rule in core — which must stay
    ///     game-agnostic and cannot have one — or a per-run offset in the module, which is the same
    ///     bug with more moving parts.
    ///
    ///     `Server.Persistence` plus `EventSink.WorldSave` writes a companion file beside the world
    ///     save rather than a persistence ITEM. No world object, no serial, nothing for a GM to find
    ///     and delete by accident, and a wipe of custom items leaves the ledger intact.
    ///
    ///     **The save/load hooks are attached unconditionally**, before the enabled gate is
    ///     consulted. An operator who switches the plane off for an afternoon must not come back to
    ///     a truncated file where a run's tally used to be.
    ///
    ///     ── The first handler that defers ──────────────────────────────────────────────────────
    ///
    ///     `participation.snapshot` resolves every member serial to a mobile and an account, so a
    ///     well-attended run is hundreds of world lookups in one inbound call — exactly the kind of
    ///     work the Core thread must not be handed in one piece. Above
    ///     `Bridge.ParticipationSnapshotChunk` members it walks in chunks across ticks.
    ///
    ///     That makes it the first handler in the bridge to complete AFTER its inbound call returns,
    ///     and therefore the first that can genuinely answer `bridge.busy` — protocol 6 built the
    ///     door in 11a with `BridgeIdempotency.Hold`/`Complete` and had nothing to walk through it.
    /// </summary>
    public static class BridgeParticipation
    {
        private static readonly string SavePath = Path.Combine("Saves", "Bridge", "Participation.bin");

        private const int SaveVersion = 1;

        /// <summary>One character's part in one run.</summary>
        private sealed class Member
        {
            public int Serial;

            /// <summary>
            ///     Last seen name, kept only so the console and the snapshot can say something
            ///     useful about a character that has since been deleted. The website resolves its
            ///     own names from the serial and never reads this.
            /// </summary>
            public string Name;

            /// <summary>
            ///     Accrued presence in SECONDS, not in sample counts.
            ///
            ///     A sample count would have to be multiplied by the sweep interval to mean
            ///     anything, and the interval is a config key an operator may change halfway
            ///     through a five-hour run — which would silently rewrite the first half of the
            ///     tally. Accruing the interval as it is actually used makes history immutable.
            /// </summary>
            public long Seconds;

            public int Kills;
            public long FirstMs;
            public long LastMs;
        }

        /// <summary>One run's declared area and its members.</summary>
        private sealed class Run
        {
            public string RunId;
            public string MapName;
            public int MapIndex;
            public int X;
            public int Y;
            public int Radius;

            public long OpenedMs;
            public long UntilMs;
            public long ClosedMs;
            public bool Closed;

            /// <summary>
            ///     Frozen at open, for the same reason presence is accrued in seconds: a weight the
            ///     operator retunes mid-run must not retroactively re-score the kills that already
            ///     happened under the old one.
            /// </summary>
            public double KillWeight;

            /// <summary>Members the cap turned away. Reported, because a truncated tally that says so is usable and one that does not is a lie.</summary>
            public long Refused;

            public Dictionary<int, Member> Members = new Dictionary<int, Member>();
        }

        private static readonly Dictionary<string, Run> _runs = new Dictionary<string, Run>(StringComparer.Ordinal);

        private static Timer _timer;

        private static long _sweeps, _opened, _closed, _snapshots, _kills, _deferred, _refused;

        /// <summary>
        ///     Attaches persistence. Runs before `World.Load()`, which is when `EventSink.WorldLoad`
        ///     fires, so this cannot be deferred to Initialize.
        /// </summary>
        [CallPriority(900)]
        public static void Configure()
        {
            EventSink.WorldSave += OnWorldSave;
            EventSink.WorldLoad += OnWorldLoad;
        }

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

            BridgeBoot.RegisterHandler("participation.open", OnOpen);
            BridgeBoot.RegisterHandler("participation.snapshot", OnSnapshot);
            BridgeBoot.RegisterHandler("participation.close", OnClose);

            EventSink.CreatureDeath += OnCreatureDeath;
            EventSink.ServerStarted += OnServerStarted;
        }

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

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

            _timer = Timer.DelayCall(
                TimeSpan.FromSeconds(BridgeConfig.ParticipationSweepSeconds),
                TimeSpan.FromSeconds(BridgeConfig.ParticipationSweepSeconds),
                Sweep);
        }

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

        public static string Status()
        {
            int members = 0;

            foreach (var run in _runs.Values)
                members += run.Members.Count;

            return String.Format(
                "participation(runs={0} members={1} sweeps={2} opened={3} closed={4} snapshots={5} kills={6} deferred={7} refused={8})",
                _runs.Count, members, _sweeps, _opened, _closed, _snapshots, _kills, _deferred, _refused);
        }

        // ---- participation.open ----

        /// <summary>
        ///     Declares a run's area and starts counting.
        ///
        ///     The area is a map, a point and a radius (org lead, 2026-09-04). Not a region name:
        ///     protocol 6's own live walk established that the most specific region containing an
        ///     event is routinely anonymous, so a region-named area would be undeclarable for
        ///     exactly the venues events use. Not a rectangle either — an author picks the spot the
        ///     event happens at, not two opposite corners of it.
        /// </summary>
        private static void OnOpen(Dictionary<string, object> o)
        {
            var reqId = BridgeJson.GetString(o, "reqId");

            if (!Ready(reqId, "open"))
                return;

            var runId = BridgeJson.GetString(o, "runId");

            if (String.IsNullOrEmpty(runId))
            {
                Err(reqId, "open", "a run id is required");
                return;
            }

            var mapName = BridgeJson.GetString(o, "map");
            var map = MapByName(mapName);

            if (map == null)
            {
                Err(reqId, "open", "unknown map '" + (mapName ?? "") + "'");
                return;
            }

            var radius = BridgeJson.GetInt(o, "radius", 0);

            if (radius < 1 || radius > BridgeConfig.ParticipationMaxRadius)
            {
                Err(reqId, "open",
                    String.Format(CultureInfo.InvariantCulture,
                        "radius must be 1 to {0} tiles, and {1} was asked for",
                        BridgeConfig.ParticipationMaxRadius, radius));
                return;
            }

            var x = BridgeJson.GetInt(o, "x", -1);
            var y = BridgeJson.GetInt(o, "y", -1);

            if (x < 0 || y < 0)
            {
                Err(reqId, "open", "an area needs an x and a y");
                return;
            }

            Run existing;

            if (_runs.TryGetValue(runId, out existing))
            {
                // Re-opening the same area is the ordinary consequence of a step being re-authored
                // or a run being resumed, and answering it as an error would fail a run for doing
                // nothing. Re-opening a DIFFERENT area is an authoring mistake, and silently
                // moving the venue mid-run would make the tally describe two places at once.
                if (existing.MapIndex != map.MapIndex || existing.X != x || existing.Y != y ||
                    existing.Radius != radius)
                {
                    Err(reqId, "open", "run " + runId + " is already counting a different area");
                    return;
                }

                existing.Closed = false;
                Ok(reqId, "open", existing);
                return;
            }

            if (_runs.Count >= BridgeConfig.ParticipationMaxRuns)
            {
                Err(reqId, "open",
                    String.Format(CultureInfo.InvariantCulture,
                        "this shard counts at most {0} runs at once", BridgeConfig.ParticipationMaxRuns));
                return;
            }

            var holdMs = BridgeJson.GetLong(o, "holdMs", 0L);
            var now = BridgeJson.NowMs();

            var run = new Run
            {
                RunId = runId,
                MapName = map.Name,
                MapIndex = map.MapIndex,
                X = x,
                Y = y,
                Radius = radius,
                OpenedMs = now,
                UntilMs = holdMs > 0L ? now + holdMs : 0L,
                KillWeight = BridgeConfig.ParticipationKillWeight,
            };

            _runs[runId] = run;
            _opened++;

            Console.WriteLine("[Bridge] participation: run {0} counting {1} tiles around {2} ({3}, {4})",
                runId, radius, map.Name, x, y);

            Ok(reqId, "open", run);
        }

        // ---- participation.close ----

        /// <summary>
        ///     Stops counting. The tally stays readable through the grace window, because the run
        ///     that closes an event and the step that collects its results are two different steps
        ///     and either can be retried.
        /// </summary>
        private static void OnClose(Dictionary<string, object> o)
        {
            var reqId = BridgeJson.GetString(o, "reqId");

            if (!Ready(reqId, "close"))
                return;

            var runId = BridgeJson.GetString(o, "runId");

            Run run;

            if (runId == null || !_runs.TryGetValue(runId, out run))
            {
                // Not an error. A close of a run this shard has already forgotten — a restart, a
                // second teardown attempt — has the same meaning as one it honoured: nothing is
                // being counted for that run any more.
                var gone = BridgeJson.Begin("participation.ok");
                if (reqId != null) gone.Str("reqId", reqId);
                gone.Str("action", "close").Str("runId", runId).Bool("closed", true).Bool("known", false);
                BridgeLink.Emit(gone.End());
                return;
            }

            if (!run.Closed)
            {
                // One last sweep before the books shut, so the people standing there when the event
                // ended are credited for the interval they were standing there in.
                SweepRun(run, BridgeConfig.ParticipationSweepSeconds);

                run.Closed = true;
                run.ClosedMs = BridgeJson.NowMs();
                _closed++;

                Console.WriteLine("[Bridge] participation: run {0} closed with {1} member(s)",
                    run.RunId, run.Members.Count);
            }

            Ok(reqId, "close", run);
        }

        // ---- participation.snapshot ----

        /// <summary>One snapshot in progress. See the class header for why this exists at all.</summary>
        private sealed class Job
        {
            public string ReqId;
            public string IdempotencyKey;
            public Run Run;
            public List<Member> Members;
            public int Index;
            public StringBuilder Sb;

            /// <summary>
            ///     Whether this job took the key out of the inbound call's hands.
            ///
            ///     Recorded rather than re-derived from the chunk size, because the chunk size is a
            ///     config key an operator may change between the Hold and the Complete — and a
            ///     Complete that did not happen leaves every retry answered `bridge.busy` until the
            ///     store evicts the key an hour later.
            /// </summary>
            public bool Held;
        }

        private static void OnSnapshot(Dictionary<string, object> o)
        {
            var reqId = BridgeJson.GetString(o, "reqId");

            if (!Ready(reqId, "snapshot"))
                return;

            var runId = BridgeJson.GetString(o, "runId");

            Run run;

            if (runId == null || !_runs.TryGetValue(runId, out run))
            {
                Err(reqId, "snapshot", "this shard is not counting run '" + (runId ?? "") + "'");
                return;
            }

            // **Copied, not iterated in place.** A sweep or a kill landing between two chunks would
            // otherwise mutate the dictionary the walk is enumerating, and a snapshot is a
            // point-in-time answer in any case: the run it describes is the run as it was when the
            // question was asked.
            var members = new List<Member>(run.Members.Values);

            var job = new Job
            {
                ReqId = reqId,
                IdempotencyKey = BridgeJson.GetString(o, "idempotencyKey"),
                Run = run,
                Members = members,
                Index = 0,
                Sb = OpenSnapshot(reqId, run, members.Count),
            };

            _snapshots++;

            if (members.Count <= BridgeConfig.ParticipationSnapshotChunk)
            {
                // Small enough to answer in the inbound call. Deliberately NOT deferred anyway: the
                // idempotency store captures a reply emitted inside the handler for free, and
                // holding a key we did not need to hold would put an ordinary command through the
                // in-flight path for no reason.
                Step(job);
                return;
            }

            // Deferring. The key must be HELD before this call returns, or a repeat arriving while
            // the walk is still running would be executed a second time rather than answered
            // `bridge.busy` — which is the entire failure protocol 6 exists to prevent, and it is
            // reachable for the first time right here.
            if (job.IdempotencyKey != null)
            {
                BridgeIdempotency.Hold(job.IdempotencyKey);
                job.Held = true;
            }

            _deferred++;
            Timer.DelayCall(TimeSpan.Zero, () => Step(job));
        }

        /// <summary>One chunk of a snapshot. Re-arms itself until the walk is done.</summary>
        private static void Step(Job job)
        {
            try
            {
                var end = Math.Min(job.Index + BridgeConfig.ParticipationSnapshotChunk, job.Members.Count);

                for (; job.Index < end; job.Index++)
                    WriteMember(job.Sb, job.Run, job.Members[job.Index], job.Index > 0);

                if (job.Index < job.Members.Count)
                {
                    Timer.DelayCall(TimeSpan.Zero, () => Step(job));
                    return;
                }

                job.Sb.Append(']');
                var line = job.Sb.End();

                BridgeLink.Emit(line);

                // Only a HELD key needs completing. An inline snapshot was captured by the
                // idempotency store on its way through Emit, and completing it twice would replace
                // a correlated reply with one this method has no correlation information for.
                if (job.Held)
                    BridgeIdempotency.Complete(job.IdempotencyKey, line);
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] participation snapshot threw: {0}", ex.Message);

                // A held key whose walk died must still be closed out, or every retry of this step
                // gets `bridge.busy` until the store's TTL evicts it an hour later.
                if (job.Held)
                {
                    var sb = BridgeJson.Begin("participation.error");
                    if (job.ReqId != null) sb.Str("reqId", job.ReqId);
                    sb.Str("action", "snapshot").Str("reason", "the snapshot failed: " + ex.Message);
                    var line = sb.End();

                    BridgeLink.Emit(line);
                    BridgeIdempotency.Complete(job.IdempotencyKey, line);
                }
            }
        }

        private static StringBuilder OpenSnapshot(string reqId, Run run, int count)
        {
            var sb = BridgeJson.Begin("participation.snapshot.ok");

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

            sb.Str("runId", run.RunId)
              .Str("map", run.MapName)
              .Num("x", run.X)
              .Num("y", run.Y)
              .Num("radius", run.Radius)
              .Bool("closed", run.Closed)
              .Num("openedMs", run.OpenedMs)
              .Num("killWeight", run.KillWeight)
              .Num("members", count)
              .Num("refused", run.Refused);

            sb.Append(",\"participants\":[");
            return sb;
        }

        /// <summary>
        ///     One member, with the score this shard computed and the two components it came from.
        ///
        ///     The components ride along because core stores the score opaquely and could never
        ///     explain it: a results table that can say "forty minutes and three kills" beside a
        ///     number is a table an operator can argue with, and one that shows only the number is
        ///     one they can only believe or not.
        /// </summary>
        private static void WriteMember(StringBuilder sb, Run run, Member member, bool comma)
        {
            if (comma)
                sb.Append(',');

            var minutes = member.Seconds / 60.0;
            var score = minutes + run.KillWeight * member.Kills;

            sb.Append("{\"serial\":\"0x").Append(((uint)member.Serial).ToString("X")).Append('"');

            // Resolved now rather than at sweep time, and the mobile is looked up whether or not
            // its owner is online: a character that took part and logged out is still in the world,
            // so its account — and the linked website user with it — is still readable.
            var mobile = World.FindMobile((Serial)member.Serial);

            sb.Append(",\"name\":");
            BridgeJson.Text(sb, mobile != null && !String.IsNullOrEmpty(mobile.Name) ? mobile.Name : member.Name);

            var acct = mobile == null ? null : mobile.Account as Accounting.Account;

            if (acct != null)
            {
                sb.Append(",\"acct\":");
                BridgeJson.Text(sb, acct.Username);

                var webId = BridgeAccountLink.WebIdFor(acct);

                if (webId != null)
                {
                    sb.Append(",\"webId\":");
                    BridgeJson.Text(sb, webId);
                }
            }

            sb.Append(",\"seconds\":").Append(member.Seconds);
            sb.Append(",\"minutes\":").Append(minutes.ToString("F2", CultureInfo.InvariantCulture));
            sb.Append(",\"kills\":").Append(member.Kills);
            sb.Append(",\"score\":").Append(score.ToString("F4", CultureInfo.InvariantCulture));
            sb.Append(",\"firstMs\":").Append(member.FirstMs);
            sb.Append(",\"lastMs\":").Append(member.LastMs);
            sb.Append('}');
        }

        // ---- counting ----

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

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

                if (_runs.Count == 0)
                    return;

                var seconds = BridgeConfig.ParticipationSweepSeconds;
                var now = BridgeJson.NowMs();
                List<string> expired = null;

                foreach (var run in _runs.Values)
                {
                    if (run.Closed)
                        continue;

                    // The run's own deadline, honoured here for the reason a lease's is honoured on
                    // the shard: a website that stopped talking must not leave this shard counting
                    // an event that ended days ago.
                    if (run.UntilMs > 0L && now >= run.UntilMs)
                    {
                        SweepRun(run, seconds);
                        run.Closed = true;
                        run.ClosedMs = now;
                        _closed++;

                        Console.WriteLine("[Bridge] participation: run {0} passed its deadline and stopped counting",
                            run.RunId);
                        continue;
                    }

                    SweepRun(run, seconds);
                }

                var cutoff = now - (long)BridgeConfig.ParticipationGraceSec * 1000L;

                foreach (var run in _runs.Values)
                {
                    if (!run.Closed || run.ClosedMs > cutoff)
                        continue;

                    if (expired == null)
                        expired = new List<string>();

                    expired.Add(run.RunId);
                }

                if (expired == null)
                    return;

                for (int i = 0; i < expired.Count; i++)
                {
                    Console.WriteLine("[Bridge] participation: forgetting run {0}, closed longer than the grace window",
                        expired[i]);

                    _runs.Remove(expired[i]);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] participation sweep threw: {0}", ex.Message);
            }
        }

        /// <summary>Credits every online player standing in one run's area with one interval.</summary>
        private static void SweepRun(Run run, int seconds)
        {
            var map = Map.Maps[run.MapIndex];

            if (map == null)
                return;

            var now = BridgeJson.NowMs();

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

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

                if (!Inside(run, pm))
                    continue;

                var member = Touch(run, pm, now);

                if (member == null)
                    continue;

                member.Seconds += seconds;
            }
        }

        /// <summary>
        ///     Kill credit, and it goes to every damager standing in the area rather than to the
        ///     killer alone.
        ///
        ///     A last hit is a poor description of who fought something: the player who held it for
        ///     four minutes and died to it took part more than the one who happened to land the blow
        ///     that finished it. `Mobile.DamageEntries` is already populated and is readable here
        ///     because a `CreatureDeath` handler runs before the creature is disposed of — the same
        ///     fact protocol 6's damage table rests on.
        ///
        ///     The presence check is applied to the DAMAGER, not only to the corpse. Someone
        ///     shooting into the venue from outside it is not attending the event, and someone who
        ///     fought there and has since walked away is no longer accruing anything either.
        /// </summary>
        private static void OnCreatureDeath(CreatureDeathEventArgs e)
        {
            try
            {
                if (_runs.Count == 0 || e == null || e.Creature == null)
                    return;

                var creature = e.Creature;

                if (creature.Player)
                    return; // a player death is not a kill anybody is credited for

                var now = BridgeJson.NowMs();

                foreach (var run in _runs.Values)
                {
                    if (run.Closed || !Inside(run, creature))
                        continue;

                    var entries = creature.DamageEntries;

                    if (entries == null)
                        continue;

                    // Summed into a set first: ServUO folds repeat damage into an existing entry,
                    // but an entry that expired and was re-created leaves two, and crediting per
                    // entry would pay a long fight twice. Expiry governs looting rights, not
                    // whether somebody was there.
                    var credited = new HashSet<Mobile>();

                    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;

                        if (!credited.Add(de.Damager))
                            continue;

                        if (!Inside(run, de.Damager))
                            continue;

                        var member = Touch(run, de.Damager, now);

                        if (member == null)
                            continue;

                        member.Kills++;
                        _kills++;
                    }
                }
            }
            catch (Exception ex)
            {
                // A death handler must never be the thing that breaks a death.
                Console.WriteLine("[Bridge] participation kill credit threw: {0}", ex.Message);
            }
        }

        private static bool Inside(Run run, Mobile m)
        {
            if (m == null || m.Map == null || m.Map.MapIndex != run.MapIndex)
                return false;

            // A circle, and squared so the check costs no square root. `Radius` is in tiles and the
            // z axis is deliberately ignored: a venue is a place on the map, and a player one floor
            // up in a tower over the square is at the event.
            var dx = m.X - run.X;
            var dy = m.Y - run.Y;

            return (dx * dx) + (dy * dy) <= run.Radius * run.Radius;
        }

        /// <summary>
        ///     Finds or creates a member row, or answers null when the cap turned it away.
        ///
        ///     The cap counts a refusal rather than swallowing it, and the count rides on every
        ///     snapshot: a truncated tally that says it is truncated is usable, and one that does
        ///     not is a leaderboard with people missing from it for no stated reason.
        /// </summary>
        private static Member Touch(Run run, Mobile m, long now)
        {
            var serial = m.Serial.Value;

            Member member;

            if (run.Members.TryGetValue((int)serial, out member))
            {
                member.LastMs = now;
                member.Name = m.Name ?? member.Name;
                return member;
            }

            if (run.Members.Count >= BridgeConfig.ParticipationMaxMembers)
            {
                run.Refused++;
                _refused++;
                return null;
            }

            member = new Member
            {
                Serial = (int)serial,
                Name = m.Name ?? "",
                FirstMs = now,
                LastMs = now,
            };

            run.Members[member.Serial] = member;
            return member;
        }

        // ---- persistence ----

        private static void OnWorldSave(WorldSaveEventArgs e)
        {
            Persistence.Serialize(
                SavePath,
                writer =>
                {
                    writer.Write(SaveVersion);
                    writer.Write(_runs.Count);

                    foreach (var run in _runs.Values)
                    {
                        writer.Write(run.RunId ?? "");
                        writer.Write(run.MapName ?? "");
                        writer.Write(run.MapIndex);
                        writer.Write(run.X);
                        writer.Write(run.Y);
                        writer.Write(run.Radius);
                        writer.Write(run.OpenedMs);
                        writer.Write(run.UntilMs);
                        writer.Write(run.ClosedMs);
                        writer.Write(run.Closed);
                        writer.Write(run.KillWeight);
                        writer.Write(run.Refused);

                        writer.Write(run.Members.Count);

                        foreach (var member in run.Members.Values)
                        {
                            writer.Write(member.Serial);
                            writer.Write(member.Name ?? "");
                            writer.Write(member.Seconds);
                            writer.Write(member.Kills);
                            writer.Write(member.FirstMs);
                            writer.Write(member.LastMs);
                        }
                    }
                });
        }

        private static void OnWorldLoad()
        {
            Persistence.Deserialize(
                SavePath,
                reader =>
                {
                    var version = reader.ReadInt();

                    if (version < 1)
                        return;

                    var runs = reader.ReadInt();

                    for (int i = 0; i < runs; i++)
                    {
                        var run = new Run
                        {
                            RunId = reader.ReadString(),
                            MapName = reader.ReadString(),
                            MapIndex = reader.ReadInt(),
                            X = reader.ReadInt(),
                            Y = reader.ReadInt(),
                            Radius = reader.ReadInt(),
                            OpenedMs = reader.ReadLong(),
                            UntilMs = reader.ReadLong(),
                            ClosedMs = reader.ReadLong(),
                            Closed = reader.ReadBool(),
                            KillWeight = reader.ReadDouble(),
                            Refused = reader.ReadLong(),
                        };

                        var members = reader.ReadInt();

                        for (int j = 0; j < members; j++)
                        {
                            var member = new Member
                            {
                                Serial = reader.ReadInt(),
                                Name = reader.ReadString(),
                                Seconds = reader.ReadLong(),
                                Kills = reader.ReadInt(),
                                FirstMs = reader.ReadLong(),
                                LastMs = reader.ReadLong(),
                            };

                            run.Members[member.Serial] = member;
                        }

                        if (!String.IsNullOrEmpty(run.RunId))
                            _runs[run.RunId] = run;
                    }

                    if (_runs.Count > 0)
                        Console.WriteLine("[Bridge] participation: {0} run(s) restored from the world save", _runs.Count);
                });
        }

        // ---- helpers ----

        private static Map MapByName(string name)
        {
            if (String.IsNullOrEmpty(name))
                return null;

            for (int i = 0; i < Map.Maps.Length; i++)
            {
                var map = Map.Maps[i];

                if (map != null && String.Equals(map.Name, name, StringComparison.OrdinalIgnoreCase))
                    return map;
            }

            return null;
        }

        private static bool Ready(string reqId, string action)
        {
            if (!BridgeConfig.EventsEnabled)
            {
                Err(reqId, action, "the event plane is disabled on this shard (Bridge.EventsEnabled)");
                return false;
            }

            return true;
        }

        private static void Ok(string reqId, string action, Run run)
        {
            var sb = BridgeJson.Begin("participation.ok");

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

            sb.Str("action", action)
              .Str("runId", run.RunId)
              .Str("map", run.MapName)
              .Num("x", run.X)
              .Num("y", run.Y)
              .Num("radius", run.Radius)
              .Bool("closed", run.Closed)
              .Bool("known", true)
              .Num("members", run.Members.Count)
              .Num("refused", run.Refused)
              .Num("untilMs", run.UntilMs);

            BridgeLink.Emit(sb.End());
        }

        private static void Err(string reqId, string action, string reason)
        {
            var sb = BridgeJson.Begin("participation.error");

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

            sb.Str("action", action).Str("reason", reason);
            BridgeLink.Emit(sb.End());
        }
    }
}