using System;
using System.Collections.Generic;

using Server.Mobiles;

namespace Server.Custom.Bridge
{
    /// <summary>
    ///     Website-published news, pushed into the game's town criers.
    ///
    ///     Inbound towncrier.add adds a global entry that every town crier announces until it
    ///     expires; towncrier.remove pulls one early. Both run on the Core thread (inbound lines are
    ///     marshaled through Timer.DelayCall before a handler sees them), which is required because
    ///     AddEntry mutates a shared list and the criers send packets.
    ///
    ///     Loopback is the trust boundary, but the caps here (line count/length, active-entry count,
    ///     duration) are defense in depth: a compromised or buggy sidecar still cannot flood the
    ///     criers or pin a message forever.
    /// </summary>
    public static class BridgeTownCrier
    {
        // Website id -> the entry we created for it, so a later remove can find it.
        private static readonly Dictionary<string, TownCrierEntry> _entries =
            new Dictionary<string, TownCrierEntry>(StringComparer.Ordinal);

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

            BridgeBoot.RegisterHandler("towncrier.add", OnAdd);
            BridgeBoot.RegisterHandler("towncrier.remove", OnRemove);
        }

        private static void Reply(string kind, string id, string reason)
        {
            var sb = BridgeJson.Begin(kind);
            if (id != null) sb.Str("id", id);
            if (reason != null) sb.Str("reason", reason);
            BridgeLink.Emit(sb.End());
        }

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

            if (id == null)
            {
                Reply("towncrier.error", null, "missing id");
                return;
            }

            var lines = BridgeJson.GetStringList(o, "lines");

            if (lines.Count == 0)
            {
                Reply("towncrier.error", id, "no lines");
                return;
            }

            if (lines.Count > BridgeConfig.TownCrierMaxLines)
            {
                Reply("towncrier.error", id, "too many lines");
                return;
            }

            // Prune expired entries from our map before enforcing the active cap.
            PruneExpired();

            // Replacing an existing id is fine; otherwise enforce the active cap.
            if (!_entries.ContainsKey(id) && _entries.Count >= BridgeConfig.TownCrierMaxActive)
            {
                Reply("towncrier.error", id, "too many active entries");
                return;
            }

            var clean = new string[lines.Count];
            for (int i = 0; i < lines.Count; i++)
            {
                var line = lines[i] ?? "";
                if (line.Length > BridgeConfig.TownCrierMaxLineLength)
                    line = line.Substring(0, BridgeConfig.TownCrierMaxLineLength);
                clean[i] = line;
            }

            int durationSec = BridgeJson.GetInt(o, "durationSec", 3600);
            if (durationSec < 1)
                durationSec = 1;
            if (durationSec > BridgeConfig.TownCrierMaxDurationSec)
                durationSec = BridgeConfig.TownCrierMaxDurationSec;

            try
            {
                // If this id already exists, replace it: remove the old entry first.
                TownCrierEntry old;
                if (_entries.TryGetValue(id, out old) && old != null)
                    GlobalTownCrierEntryList.Instance.RemoveEntry(old);

                var entry = GlobalTownCrierEntryList.Instance.AddEntry(clean, TimeSpan.FromSeconds(durationSec));
                _entries[id] = entry;

                Reply("towncrier.ok", id, null);
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] towncrier.add threw: {0}", ex.Message);
                Reply("towncrier.error", id, "internal error");
            }
        }

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

            if (id == null)
            {
                Reply("towncrier.error", null, "missing id");
                return;
            }

            TownCrierEntry entry;
            if (!_entries.TryGetValue(id, out entry))
            {
                Reply("towncrier.error", id, "unknown id");
                return;
            }

            _entries.Remove(id);

            try
            {
                if (entry != null)
                    GlobalTownCrierEntryList.Instance.RemoveEntry(entry);

                Reply("towncrier.ok", id, null);
            }
            catch (Exception ex)
            {
                Console.WriteLine("[Bridge] towncrier.remove threw: {0}", ex.Message);
                Reply("towncrier.error", id, "internal error");
            }
        }

        private static void PruneExpired()
        {
            var doomed = new List<string>();

            foreach (var kv in _entries)
            {
                if (kv.Value == null || kv.Value.Expired)
                    doomed.Add(kv.Key);
            }

            foreach (var id in doomed)
                _entries.Remove(id);
        }
    }
}