using System;
using System.Collections.Generic;
using System.Globalization;

using Server.Items;
using Server.Misc;
using Server.Mobiles;

namespace Server.Custom.Bridge
{
    /// <summary>
    ///     Protocol 7, part b. The two verbs that are neither owned nor borrowed: an item put into
    ///     someone's hands, and a world save.
    ///
    ///     EVENTS_PLAN.md Phase 12b. Everything else the event plane does is a thing this shard can
    ///     take back — a creature it deletes, a value it restores. These two are not, and they are
    ///     in the same file because that is what they have in common: <b>done is done</b>.
    ///
    ///     ── The grant, and why §8's exclusion of it was reopened separately ────────────────────
    ///
    ///     `ADMIN_CONTROLS.md` §8 cut item grants along with world creation, and §N1 reopened both —
    ///     deliberately as two reversals rather than one, because permitting an event to create a
    ///     creature says nothing about permitting it to hand out loot. What makes this grant a
    ///     different proposition from the one §8 refused is four properties it did not have then,
    ///     and all four are visible in this file:
    ///
    ///       - **Declared, not typed.** The allowlist below is the shard's, and an item not on it
    ///         cannot be granted however the request is spelled. There is no free-text type name
    ///         reaching `Activator.CreateInstance` — that is `[add`, which §G excludes.
    ///       - **Bounded.** `EventsMaxGrantPerRun` bounds the whole run and
    ///         `EventsMaxGrantStack` bounds one hand; both refuse rather than clamp.
    ///       - **Attributable.** The run id rides on every grant and is logged with it.
    ///       - **Idempotent.** Protocol 6's key means a lost acknowledgement cannot double a
    ///         reward, which is the failure that made §G call the grant un-retryable when it was
    ///         written. It is retryable now, and 11a is the whole reason.
    ///
    ///     ── Who receives it is answered HERE, and that is the interesting decision ─────────────
    ///
    ///     A grant needs a list of people, and the website has one — `event_run_participants`. It
    ///     would have had to reach through core to get it, because a module cannot read core's
    ///     tables, so the alternative was a new core surface handing participants to a module's
    ///     `perform()`.
    ///
    ///     It is not needed: **this shard already has the list**, in 11b's run-scoped participation
    ///     ledger, keyed by the same character serials the website's `member_key` holds. So the
    ///     grant names a run and the recipients are resolved from the ledger the run has been
    ///     keeping all along — no new core surface, no participant list crossing the wire twice,
    ///     and no window in which the two disagree.
    ///
    ///     A run with no open ledger grants to nobody and says so, rather than granting to
    ///     everybody online. "Everyone present" is not a thing this file will guess at.
    ///
    ///     ── The save ──────────────────────────────────────────────────────────────────────────
    ///
    ///     `ADMIN_CONTROLS.md` §3.6 catalogued it Tier B and it was never built. It is useful as a
    ///     phase boundary — the point in an event after which what has happened is safe from a
    ///     crash — and `world.save.before` / `world.save.after` are already on the wire, so the
    ///     acknowledgement it needs exists.
    ///
    ///     **A save stops the world**, so unlike every other verb here it is rate-limited by the
    ///     shard rather than only capped: `EventsMinSaveIntervalSec` refuses a save that comes too
    ///     soon after the last one, whether the last one was an event's or ServUO's own autosave.
    ///     Refuses, never queues — a queued save would arrive at a moment nobody chose.
    /// </summary>
    public static class BridgeOneShots
    {
        // ---- the grant allowlist ----

        /// <summary>
        ///     One grantable item: what an author names it, and what this shard builds.
        ///
        ///     **The list is short and boring on purpose.** Every entry is a thing an event
        ///     plausibly hands out and nothing here is equipment with rolled properties — an
        ///     artifact generator behind an unattended schedule is a different proposition and one
        ///     nobody has asked for. An operator who wants more edits this array, which is a
        ///     deployment they control rather than a field on a web form.
        /// </summary>
        private sealed class GrantEntry
        {
            public string Key;
            public string Label;
            public string Type;
        }

        private static readonly GrantEntry[] Grants =
        {
            new GrantEntry { Key = "gold", Label = "Gold", Type = "Server.Items.Gold" },
            new GrantEntry { Key = "cloak", Label = "Cloak", Type = "Server.Items.Cloak" },
            new GrantEntry { Key = "sandals", Label = "Sandals", Type = "Server.Items.Sandals" },
            new GrantEntry { Key = "candle", Label = "Candle", Type = "Server.Items.Candle" },
            new GrantEntry { Key = "earrings", Label = "Silver earrings", Type = "Server.Items.SilverEarrings" },
            new GrantEntry { Key = "fireworks", Label = "Fireworks wand", Type = "Server.Items.FireworksWand" },
            new GrantEntry { Key = "bottle", Label = "Message in a bottle", Type = "Server.Items.MessageInABottle" },
        };

        private static long _granted, _saves, _refused;

        private static long _lastSaveMs;

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

            BridgeBoot.RegisterHandler("item.grant", OnGrant);
            BridgeBoot.RegisterHandler("item.catalog", OnCatalog);
            BridgeBoot.RegisterHandler("world.save", OnSave);

            // Counted whoever asked for it, so the interval below also covers ServUO's own
            // autosave. An event save landing thirty seconds after the hourly one is the same
            // freeze twice, and the shard is the only half that can see both.
            EventSink.WorldSave += (e) => { _lastSaveMs = BridgeJson.NowMs(); };
        }

        public static string Status()
        {
            return String.Format("oneshots(granted={0} saves={1} refused={2})", _granted, _saves, _refused);
        }

        // ---- item.catalog ----

        /// <summary>
        ///     What this shard is willing to grant.
        ///
        ///     A read, so the website's option source can offer real choices — and the module holds
        ///     the same list, so the dropdown still works with the shard down. Two copies of a
        ///     short allowlist, exactly like the lease bounds: the module's is what makes a bad
        ///     value a refusal on a form, and this one is what is true when the website is wrong.
        /// </summary>
        private static void OnCatalog(Dictionary<string, object> o)
        {
            var reqId = BridgeJson.GetString(o, "reqId");

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

            var sb = BridgeJson.Begin("item.catalog.ok");
            if (reqId != null) sb.Str("reqId", reqId);

            sb.Append(",\"items\":[");

            for (int i = 0; i < Grants.Length; i++)
            {
                if (i > 0)
                    sb.Append(',');

                sb.Append("{\"key\":");
                BridgeJson.Text(sb, Grants[i].Key);
                sb.Append(",\"label\":");
                BridgeJson.Text(sb, Grants[i].Label);
                sb.Append(",\"stackable\":").Append(Stackable(Grants[i]) ? "true" : "false");
                sb.Append('}');
            }

            sb.Append(']');
            sb.Append(",\"maxPerRun\":").Append(BridgeConfig.EventsMaxGrantPerRun);
            sb.Append(",\"maxStack\":").Append(BridgeConfig.EventsMaxGrantStack);
            BridgeLink.Emit(sb.End());
        }

        // ---- item.grant ----

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

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

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

            if (String.IsNullOrEmpty(runId))
            {
                Err(reqId, "grant", "a grant needs a runId");
                return;
            }

            var entry = LookupGrant(BridgeJson.GetString(o, "item"));

            if (entry == null)
            {
                Err(reqId, "grant", "this shard does not grant '" + BridgeJson.GetString(o, "item") + "'");
                return;
            }

            var amount = (int)BridgeJson.GetLong(o, "amount", 1L);

            if (amount < 1)
            {
                Err(reqId, "grant", "a grant needs a positive amount");
                return;
            }

            // Refused rather than clamped, on `LeaseMaxDurationSec`'s argument from 11b: the
            // website is the half that records what was handed out, and a silent clamp would make
            // its ledger a description of a grant that did not happen.
            if (amount > BridgeConfig.EventsMaxGrantStack)
            {
                Err(reqId, "grant", String.Format(CultureInfo.InvariantCulture,
                    "this shard grants at most {0} at a time, and {1} were asked for",
                    BridgeConfig.EventsMaxGrantStack, amount));
                return;
            }

            var toBank = String.Equals(BridgeJson.GetString(o, "where"), "bank", StringComparison.OrdinalIgnoreCase);

            var serials = BridgeParticipation.MemberSerials(runId);

            if (serials == null)
            {
                Err(reqId, "grant", "run " + runId + " has no participation ledger open on this shard");
                return;
            }

            if (serials.Count == 0)
            {
                // Not a refusal: a run whose event nobody attended is a real outcome, and the
                // website needs to record a grant that reached nobody rather than a failed step it
                // will retry against the same empty ledger.
                var none = BridgeJson.Begin("item.grant.ok");
                if (reqId != null) none.Str("reqId", reqId);
                none.Str("runId", runId).Str("item", entry.Key);
                none.Append(",\"granted\":0,\"missed\":[]");
                BridgeLink.Emit(none.End());
                return;
            }

            if (serials.Count > BridgeConfig.EventsMaxGrantPerRun)
            {
                Err(reqId, "grant", String.Format(CultureInfo.InvariantCulture,
                    "that run has {0} participants and this shard grants to at most {1}",
                    serials.Count, BridgeConfig.EventsMaxGrantPerRun));
                return;
            }

            var hue = (int)BridgeJson.GetLong(o, "hue", 0L);
            var name = BridgeJson.GetString(o, "name");

            if (name != null && name.Length > 40)
                name = name.Substring(0, 40);

            var granted = 0;
            var missed = new List<string>();

            for (int i = 0; i < serials.Count; i++)
            {
                var mobile = World.FindMobile((Serial)serials[i]) as PlayerMobile;

                if (mobile == null || mobile.Deleted)
                {
                    missed.Add(Hex(serials[i]) + ": no such character");
                    continue;
                }

                string why;

                if (Give(mobile, entry, amount, hue, name, toBank, out why))
                    granted++;
                else
                    missed.Add(Hex(serials[i]) + ": " + why);
            }

            _granted += granted;

            Console.WriteLine("[Bridge] grant {0} x{1} to run {2}: {3} of {4}",
                entry.Key, amount, runId, granted, serials.Count);

            var sb = BridgeJson.Begin("item.grant.ok");
            if (reqId != null) sb.Str("reqId", reqId);
            sb.Str("runId", runId).Str("item", entry.Key);
            sb.Append(",\"granted\":").Append(granted);
            sb.Append(",\"missed\":[");

            for (int i = 0; i < missed.Count; i++)
            {
                if (i > 0) sb.Append(',');
                BridgeJson.Text(sb, missed[i]);
            }

            sb.Append(']');
            BridgeLink.Emit(sb.End());
        }

        /// <summary>
        ///     Builds and hands over one grant, or says why it could not.
        ///
        ///     **A grant that cannot be delivered is deleted rather than dropped on the floor.**
        ///     `AddItem` failing on a full backpack would otherwise leave the item in the world at
        ///     (0,0) — a real ServUO trap — and an event that quietly littered the map with
        ///     undeliverable rewards would be worse than one that reported a miss.
        /// </summary>
        private static bool Give(PlayerMobile mobile, GrantEntry entry, int amount, int hue, string name, bool toBank, out string why)
        {
            why = null;

            var container = toBank ? (Container)mobile.BankBox : mobile.Backpack;

            if (container == null || container.Deleted)
            {
                why = toBank ? "no bank box" : "no backpack";
                return false;
            }

            Item item;

            try
            {
                item = Build(entry);
            }
            catch (Exception e)
            {
                why = "could not be created (" + e.Message + ")";
                return false;
            }

            if (item == null)
            {
                why = "could not be created";
                return false;
            }

            if (item.Stackable)
            {
                item.Amount = amount;
            }
            else if (amount > 1)
            {
                // A non-stackable granted in quantity would be N items, and N items is N chances to
                // overflow a backpack halfway through with no way to report which half landed.
                // One is what an event means by "a commemorative cloak" anyway.
                item.Delete();
                why = "is not stackable, so it can only be granted one at a time";
                return false;
            }

            if (hue > 0)
                item.Hue = hue;

            if (!String.IsNullOrEmpty(name))
                item.Name = name;

            if (!container.TryDropItem(mobile, item, false))
            {
                item.Delete();
                why = toBank ? "bank box is full" : "backpack is full";
                return false;
            }

            return true;
        }

        private static Item Build(GrantEntry entry)
        {
            var type = ScriptCompiler.FindTypeByFullName(entry.Type);

            if (type == null)
                return null;

            return Activator.CreateInstance(type) as Item;
        }

        private static bool Stackable(GrantEntry entry)
        {
            Item probe = null;

            try
            {
                probe = Build(entry);
                return probe != null && probe.Stackable;
            }
            catch
            {
                return false;
            }
            finally
            {
                if (probe != null)
                    probe.Delete();
            }
        }

        // ---- world.save ----

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

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

            var since = BridgeJson.NowMs() - _lastSaveMs;
            var minimum = (long)BridgeConfig.EventsMinSaveIntervalSec * 1000L;

            if (_lastSaveMs > 0L && since < minimum)
            {
                // **Refused, not queued.** A queued save would land at a moment nobody chose, in the
                // middle of whatever the next step is doing. Refusing tells the website exactly what
                // happened, and a save skipped because one just happened has cost nothing.
                Err(reqId, "save", String.Format(CultureInfo.InvariantCulture,
                    "this shard saves at most every {0} seconds, and the last save was {1} seconds ago",
                    BridgeConfig.EventsMinSaveIntervalSec, since / 1000L));
                return;
            }

            // `world.save.before` and `world.save.after` are emitted by `BridgeEvents` from ServUO's
            // own hooks, so the acknowledgement of what actually happened rides those rather than
            // being asserted here. This reply says only that the save was STARTED.
            _saves++;
            AutoSave.Save();

            var sb = BridgeJson.Begin("world.save.ok");
            if (reqId != null) sb.Str("reqId", reqId);
            sb.Bool("started", true);
            BridgeLink.Emit(sb.End());
        }

        // ---- helpers ----

        private static GrantEntry LookupGrant(string key)
        {
            if (key == null)
                return null;

            for (int i = 0; i < Grants.Length; i++)
            {
                if (String.Equals(Grants[i].Key, key, StringComparison.OrdinalIgnoreCase))
                    return Grants[i];
            }

            return null;
        }

        private static string Hex(int serial)
        {
            return "0x" + serial.ToString("X", CultureInfo.InvariantCulture);
        }

        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 Err(string reqId, string action, string reason)
        {
            _refused++;

            var sb = BridgeJson.Begin("oneshot.error");
            if (reqId != null) sb.Str("reqId", reqId);
            sb.Str("action", action).Str("reason", reason);
            BridgeLink.Emit(sb.End());
        }
    }
}