using System;
using System.Collections.Generic;

using Server.Commands;

namespace Server.Custom.Bridge
{
    /// <summary>
    ///     Lifecycle wiring. Boot order (Server/Main.cs:544-562, all on the Core thread):
    ///
    ///         Configure()  ->  World.Load()  ->  Initialize()  ->  EventSink.ServerStarted
    ///
    ///     Config is read in Configure. Handlers are attached in Initialize. The socket opens on
    ///     ServerStarted, once the world is actually there to describe.
    ///
    ///     EventSink.Shutdown does NOT fire on a crash (Server/Main.cs:198,313), so the sidecar
    ///     must treat socket EOF as normal and re-handshake rather than waiting for a goodbye.
    /// </summary>
    public static class BridgeBoot
    {
        private static readonly Dictionary<string, Action<Dictionary<string, object>>> _handlers =
            new Dictionary<string, Action<Dictionary<string, object>>>(StringComparer.Ordinal);

        /// <summary>
        ///     Identifies this run of the shard. It is stable across sidecar reconnects and changes
        ///     on every shard restart, which is how the sidecar tells "I reconnected" (keep my
        ///     cached state) from "the shard restarted" (discard it).
        /// </summary>
        private static string _bootId;

        public static void Configure()
        {
            BridgeConfig.Configure();
        }

        public static void Initialize()
        {
            if (!BridgeConfig.Enabled)
            {
                Console.WriteLine("[Bridge] disabled by config");
                return;
            }

            CommandSystem.Register("bridge", AccessLevel.Administrator, Bridge_OnCommand);

            RegisterHandler("ping", OnPing);

            BridgeLink.InboundLine += OnInboundLine;
            BridgeLink.Connected_Core += EmitHello;

            EventSink.ServerStarted += OnServerStarted;
            EventSink.Shutdown += OnShutdown;
            EventSink.Crashed += OnCrashed;

            Console.WriteLine("[Bridge] {0}", BridgeConfig.Describe());
        }

        /// <summary>Handlers run on the Core thread. They may touch the world freely.</summary>
        public static void RegisterHandler(string kind, Action<Dictionary<string, object>> handler)
        {
            _handlers[kind] = handler;
        }

        private static void OnServerStarted()
        {
            _bootId = Guid.NewGuid().ToString("N");
            BridgeLink.Start();
        }

        /// <summary>
        ///     Core thread, once per connection. The sidecar restarts independently of the shard,
        ///     so this is sent on every connect rather than once at boot — otherwise a sidecar that
        ///     came up second would never learn which shard it is talking to.
        /// </summary>
        private static void EmitHello()
        {
            BridgeLink.Emit(BridgeJson.Begin("server.hello")
                .Str("shard", Server.Misc.ServerList.ServerName)
                .Str("bootId", _bootId)
                .Num("connects", BridgeLink.Connects)
                .Num("items", World.Items.Count)
                .Num("mobiles", World.Mobiles.Count)
                .Num("accounts", Accounting.Accounts.Count)
                .End());
        }

        private static void OnShutdown(ShutdownEventArgs e)
        {
            BridgeLink.Emit(BridgeJson.Begin("server.shutdown").End());

            // Stop() joins the link thread for up to 2s, which gives the writer a chance to drain
            // the goodbye. Best effort: the sidecar must not depend on receiving it.
            BridgeLink.Stop();
        }

        private static void OnCrashed(CrashedEventArgs e)
        {
            try
            {
                BridgeLink.Emit(BridgeJson.Begin("server.crashed")
                    .Str("error", e.Exception == null ? null : e.Exception.Message)
                    .End());

                BridgeLink.Stop();
            }
            catch
            {
                // The process is already going down. Never make a crash worse.
            }
        }

        /// <summary>Core thread, one call per inbound line.</summary>
        private static void OnInboundLine(string line)
        {
            var obj = BridgeJson.Parse(line);

            if (obj == null)
            {
                Console.WriteLine("[Bridge] malformed inbound line, ignoring");
                return;
            }

            var kind = BridgeJson.GetString(obj, "kind");

            if (kind == null)
                return;

            Action<Dictionary<string, object>> handler;

            if (!_handlers.TryGetValue(kind, out handler))
            {
                Console.WriteLine("[Bridge] no handler for inbound kind '{0}'", kind);
                return;
            }

            handler(obj);
        }

        private static void OnPing(Dictionary<string, object> o)
        {
            var sb = BridgeJson.Begin("pong");

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

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

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

        [Usage("bridge [status | reload | ping | sweepnow]")]
        [Description("Inspects and controls the sidecar link.")]
        private static void Bridge_OnCommand(CommandEventArgs e)
        {
            var arg = e.Length > 0 ? e.GetString(0).ToLowerInvariant() : "status";

            switch (arg)
            {
                case "reload":
                    BridgeConfig.Load();
                    BridgeSweeps.Rearm();
                    BridgePages.Rearm();
                    BridgeChamps.Rearm();
                    BridgeSocial.Rearm();
                    BridgeGovernance.Rearm();
                    e.Mobile.SendMessage("Bridge: {0}", BridgeConfig.Describe());
                    e.Mobile.SendMessage("Bridge: sweeps re-armed; endpoint changes take effect on reconnect.");
                    break;

                case "ping":
                    BridgeLink.Emit(BridgeJson.Begin("ping").End());
                    e.Mobile.SendMessage("Bridge: ping queued.");
                    break;

                case "sweepnow":
                    BridgeSweeps.SweepOnce();
                    BridgeChamps.SweepOnce();
                    BridgeSocial.SweepOnce();
                    BridgeGovernance.SweepOnce();
                    e.Mobile.SendMessage("Bridge: ran one sweep of each stream.");
                    e.Mobile.SendMessage("Bridge: {0}", BridgeSweeps.Status());
                    e.Mobile.SendMessage("Bridge: {0}", BridgeChamps.Status());
                    e.Mobile.SendMessage("Bridge: {0}", BridgeSocial.Status());
                    e.Mobile.SendMessage("Bridge: {0}", BridgeGovernance.Status());
                    break;

                default:
                    e.Mobile.SendMessage("Bridge: {0}", BridgeConfig.Describe());
                    e.Mobile.SendMessage(
                        "Bridge: connected={0} depth={1} sent={2} dropped={3} received={4} connects={5} writeErrors={6}",
                        BridgeLink.Connected, BridgeLink.Depth, BridgeLink.Sent, BridgeLink.Dropped,
                        BridgeLink.Received, BridgeLink.Connects, BridgeLink.WriteErrors);
                    e.Mobile.SendMessage("Bridge: {0}", BridgeSweeps.Status());
                    e.Mobile.SendMessage("Bridge: {0}", BridgeChamps.Status());
                    e.Mobile.SendMessage("Bridge: {0}", BridgeSocial.Status());
                    e.Mobile.SendMessage("Bridge: {0}", BridgeGovernance.Status());
                    e.Mobile.SendMessage("Bridge: {0}", BridgePages.Status());
                    break;
            }
        }
    }
}