using System.Reflection;
using CounterStrikeSharp.API;
using CounterStrikeSharp.API.Core;
using CounterStrikeSharp.API.Modules.Timers;
using CounterStrikeSharp.API.Modules.Utils;
using Microsoft.Extensions.Logging;
using Outnumbered.Engine;

namespace Outnumbered;

// Survival "effect" card subsystems that don't belong to a single hook: the Burn DoT registry + tick, and the
// Explode-on-Kill real-grenade spawn. Both are survival-only by gating (the cards only exist there) but the code is
// mode-agnostic. The native projectile-create + the raw attributed hit live in Engine (GrenadeSpawner / DamageDealer);
// this owns only the burn registry + per-tick bookkeeping. Wired from Outnumbered.cs (Initialize_Effects / Shutdown_Effects).
public sealed partial class OutnumberedPlugin
{
    // Burn DoT: keyed by (bot slot, attacker slot) so each attacker burns a bot INDEPENDENTLY (different players STACK;
    // a player's own re-hit just refreshes their entry). Value = (when this attacker's burn expires, attacker SteamID for
    // identity-revalidation against slot reuse). Flat DPS from config; the tick deals it via a RAW (armor-skipping) hit.
    private readonly Dictionary<(int bot, int atk), (double until, ulong sid)> _burns = new();
    private readonly List<KeyValuePair<(int bot, int atk), (double until, ulong sid)>> _burnScratch = new(); // reused snapshot for BurnTickAll
    private CounterStrikeSharp.API.Modules.Timers.Timer? _burnTimer;

    private void Initialize_Effects()
    {
        // Every effect-card key must have a catalog entry in Config.Survival.Cards, or the draft can never offer it
        // (a typo'd/renamed key on the shared JSON silently disables that card on all 8 servers). Reflect over CardKeys
        // so a newly-added constant is covered automatically.
        var cardKeys = Config.Survival.Cards.Select(c => c.Key).ToHashSet(StringComparer.Ordinal);
        foreach (var f in typeof(CardKeys).GetFields(BindingFlags.Public | BindingFlags.Static))
            if (f.IsLiteral && f.GetRawConstantValue() is string key && !cardKeys.Contains(key))
                Logger.LogError("Outnumbered: CardKeys.{Name} ('{Key}') has no entry in Config.Survival.Cards — that effect card can never be drafted.", f.Name, key);

        // One steady tick (no-op when the registry is empty, i.e. in TDM/GG or a survival run with no Burn cards).
        _burnTimer = AddTimer(Math.Max(0.1f, Config.Survival.BurnTickSeconds), BurnTickAll, TimerFlags.REPEAT);
    }

    private void Shutdown_Effects()
    {
        _burnTimer?.Kill();
        _burns.Clear();
    }

    // A human with the Burn card hit a bot — (re)apply this attacker's burn on that bot.
    private void RegisterBurn(int botSlot, int atkSlot, ulong atkSid)
    {
        _burns[(botSlot, atkSlot)] = (Server.CurrentTime + Config.Survival.BurnDurationSeconds, atkSid);
    }

    // A bot died — drop all its burns so a fast slot-reuse (suicide/respawn within the burn window) can't inherit fire.
    private void ClearBurnsForBot(int botSlot)
    {
        if (_burns.Count == 0) return;
        List<(int, int)>? gone = null;
        foreach (var k in _burns.Keys) if (k.bot == botSlot) (gone ??= new()).Add(k);
        if (gone is not null) foreach (var k in gone) _burns.Remove(k);
    }

    // Apply one tick of burn to every live burning bot, per attacker (so 5 shooters = 5x the DPS). Flat, armor-skipping,
    // still attributed (a burn KILL credits the player -> wave count / XP / explode-on-kill chaining). Prune expired or
    // now-invalid entries (bot dead/gone, attacker gone or slot reused).
    private void BurnTickAll()
    {
        if (_burns.Count == 0) return;
        double now = Server.CurrentTime;
        float dmg = (float)(Config.Survival.BurnDamagePerSecond * Config.Survival.BurnTickSeconds);

        // Iterate a SNAPSHOT: a LETHAL raw tick fires player_death synchronously inside DamageDealer.Deal's Invoke ->
        // OnPlayerDeath_Driver (Pre, inline) -> ClearBurnsForBot -> _burns.Remove, which would corrupt a live foreach
        // ("Collection was modified"). The snapshot makes that mid-loop mutation harmless; ContainsKey skips any entry
        // already cleared this tick (e.g. a co-attacker's burn on a bot an earlier entry just killed). Reused scratch
        // (BurnTickAll isn't re-entrant + game-thread) avoids a per-tick List alloc.
        _burnScratch.Clear();
        foreach (var kv in _burns) _burnScratch.Add(kv);
        foreach (var kv in _burnScratch)
        {
            if (!_burns.ContainsKey(kv.Key)) continue;
            var (botSlot, atkSlot) = kv.Key;
            var (until, sid) = kv.Value;

            var bot = Utilities.GetPlayerFromSlot(botSlot);
            if (now >= until || !IsLiveBot(bot))
            { _burns.Remove(kv.Key); continue; } // safe to mutate _burns here: we're iterating the _burnScratch snapshot

            var atk = Utilities.GetPlayerFromSlot(atkSlot);
            if (atk is not { IsValid: true } || atk.AuthorizedSteamID?.SteamId64 != sid) // attacker left / slot reused
            { _burns.Remove(kv.Key); continue; } // safe to mutate _burns here: we're iterating the _burnScratch snapshot

            if (dmg > 0) DamageDealer.Deal(bot, atk, dmg, raw: true);
        }
    }

    // Explode-on-Kill: a REAL HE blast at the corpse, attributed to `attacker` so its kills credit them (wave count +
    // chaining: a blast kill fires its own death event -> re-triggers this). The blast re-enters our offense hook (attacker
    // = the thrower) so it SCALES with the killer's build + handicap (owner's call); CT team means it never hurts survivors
    // (ff off). The native projectile-create + the manual blast fallback both live in Engine.GrenadeSpawner.
    internal void ExplodeAt(CCSPlayerController attacker, Vector pos)
    {
        var cfg = Config.Survival;
        GrenadeSpawner.Explode(attacker, pos, (float)cfg.ExplodeBaseDamage, (float)cfg.ExplodeRadius, cfg.ExplodeFuseSeconds,
            (msg, ex) => { if (ex is null) LogSurvival(msg); else Logger.LogWarning(ex, "[Survival] {Msg}", msg); }); // sig/invoke breaks log full stack at WARNING
    }
}