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

using Server.Guilds;

namespace Server.Custom.Bridge
{
    /// <summary>
    ///     The guild stream (https://gitea.whitlocktech.com/RunicGateway/docs/src/branch/main/link/PROTOCOL_2.md §10.1). Guilds have almost no useful EventSink:
    ///     EventSink.CreateGuild is only the load-time deserialization factory (Server/World.cs), and
    ///     leave/disband/leader/alliance changes raise nothing. Only EventSink.JoinGuild is real. So,
    ///     exactly like <see cref="BridgeChamps"/>, the roster is polled: enumerate BaseGuild.List each
    ///     tick, fold each guild to a small signature, and emit `guild.update` only when it changes.
    ///     A guild that vanishes (or disbands — Disbanded == leader gone) leaves via `guild.remove`.
    ///
    ///     On top of the board we emit a real-time `guild.join` from EventSink.JoinGuild, so a "so-and-
    ///     so joined" feed does not wait for the next sweep. A membership change also moves the board
    ///     signature (member count + serial sum), so a *leave* surfaces as the member count dropping in
    ///     the next `guild.update`; per-member leave events would need a core tap and are a later
    ///     refinement (§10.1).
    ///
    ///     "Created" is derived sidecar-side from a first-seen id (as champs derive it), rather than a
    ///     wire event — otherwise a sidecar reconnect, which clears the diff cache and re-emits every
    ///     guild, would look like every guild being created at once.
    /// </summary>
    public static class BridgeSocial
    {
        private static Timer _timer;

        // guild id -> last-emitted signature. An id absent here has never been emitted (or the cache
        // was cleared on reconnect), so its next sweep counts as a change.
        private static readonly Dictionary<int, string> _last = new Dictionary<int, string>();

        private static long _sweeps, _emitted, _removed, _joins;

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

            EventSink.JoinGuild += OnJoinGuild;
            EventSink.ServerStarted += OnServerStarted;
        }

        private static void OnServerStarted()
        {
            BridgeLink.Connected_Core += OnConnected;
            Rearm();
        }

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

        /// <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.GuildSweepSeconds),
                TimeSpan.FromSeconds(BridgeConfig.GuildSweepSeconds),
                GuildSweep);
        }

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

        public static string Status()
        {
            return String.Format("guilds(sweeps={0} emitted={1} removed={2} joins={3} tracked={4})",
                _sweeps, _emitted, _removed, _joins, _last.Count);
        }

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

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

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

                var seen = new HashSet<int>();

                foreach (var bg in BaseGuild.List.Values)
                {
                    var g = bg as Guild;

                    // Skip disbanded guilds (leader gone): they linger in the list until cleaned up,
                    // and treating them as absent lets the "gone" pass below emit guild.remove.
                    if (g == null || g.Disbanded)
                        continue;

                    seen.Add(g.Id);

                    var sig = Signature(g);

                    string prior;
                    if (_last.TryGetValue(g.Id, out prior) && prior == sig)
                        continue; // unchanged since last emit

                    _last[g.Id] = sig;
                    BridgeLink.Emit(WriteGuild(g));
                    _emitted++;
                }

                // Anything tracked last sweep but not seen now has disbanded or been removed.
                var gone = _last.Keys.Where(k => !seen.Contains(k)).ToList();
                foreach (var id in gone)
                {
                    _last.Remove(id);
                    BridgeLink.Emit(BridgeJson.Begin("guild.remove").Num("id", id).End());
                    _removed++;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] guild sweep threw: {0}", ex.Message);
            }
        }

        // The volatile fields that define a meaningful change: name, abbreviation, leader, member
        // count, the member set (order-independent serial sum), and alliance.
        private static string Signature(Guild g)
        {
            long memberSum = 0;
            int count = 0;

            var members = g.Members;
            if (members != null)
            {
                for (int i = 0; i < members.Count; i++)
                {
                    var m = members[i];
                    if (m == null)
                        continue;
                    count++;
                    unchecked { memberSum += (uint)m.Serial.Value; }
                }
            }

            var leaderSerial = g.Leader == null ? 0 : g.Leader.Serial.Value;

            return String.Concat(
                g.Name ?? "", "|",
                g.Abbreviation ?? "", "|",
                leaderSerial.ToString(), "|",
                count.ToString(), "|",
                memberSum.ToString(), "|",
                g.Alliance == null ? "" : (g.AllianceName ?? ""));
        }

        private static string WriteGuild(Guild g)
        {
            int online = 0, count = 0;
            var members = g.Members;
            if (members != null)
            {
                for (int i = 0; i < members.Count; i++)
                {
                    var m = members[i];
                    if (m == null)
                        continue;
                    count++;
                    if (m.NetState != null)
                        online++;
                }
            }

            var sb = BridgeJson.Begin("guild.update")
                .Num("id", g.Id)
                .Str("name", g.Name)
                .Str("abbr", g.Abbreviation)
                .Num("members", count)
                .Num("online", online)
                .Str("alliance", g.Alliance == null ? null : g.AllianceName);

            sb.Actor("leader", g.Leader);

            return sb.End();
        }

        // ---- real-time join ----

        private static void OnJoinGuild(JoinGuildEventArgs e)
        {
            try
            {
                if (e == null || e.Mobile == null)
                    return;

                var g = e.Guild as Guild;

                var sb = BridgeJson.Begin("guild.join");
                if (g != null)
                    sb.Num("id", g.Id).Str("name", g.Name).Str("abbr", g.Abbreviation);
                sb.Actor("who", e.Mobile);
                BridgeLink.Emit(sb.End());
                _joins++;
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] guild join handler threw: {0}", ex.Message);
            }
        }
    }
}