using System.Collections.Generic;
using ProjectM.Simulation;
using Unity.Entities;
using Unity.Mathematics;
using Unity.NetCode;
using Unity.Transforms;
using UnityEngine;
using static ProjectM.Client.FeedbackFx;

namespace ProjectM.Client
{
    /// <summary>
    /// Client-only BLIGHT-GEYSER telegraph + erupt VFX (Phase 1.5b bundle 3; Geyser_Build_Spec). Observe-only
    /// <see cref="SystemBase"/> in <see cref="PresentationSystemGroup"/> — sibling of
    /// <see cref="EnemyDangerTelegraphSystem"/>, never mutates the sim. Reads each geyser's replicated
    /// <see cref="Geyser.NextEruptTick"/> against the client's PREDICTED <c>NetworkTime.ServerTick</c> and derives
    /// everything from that ABSOLUTE tick (never an edge on the field — so it survives snapshot loss + relevancy
    /// re-entry; the design-review-hardened contract, review wf_900e9965-8f0 H1):
    /// <list type="bullet">
    /// <item>a growing/pulsing warning DISC at <see cref="Tuning.GeyserEruptRadius"/> over the last
    /// <see cref="Tuning.GeyserTelegraphTicks"/> before the eruption (the absolute-tick countdown, exactly the
    /// enemy-telegraph idiom);</item>
    /// <item>the erupt BURST fired when the countdown CROSSES <c>&gt;0 → &lt;=0</c>, LATCHED once per
    /// <c>NextEruptTick</c> value + an ARM-guard (only if a prior frame saw it counting down) — immune to the
    /// <c>0→stamp</c> phantom, relevancy re-entry mid-period, and snapshot loss.</item>
    /// </list>
    /// Erupt VFX reuse the shipped statics — <see cref="FeedbackFx"/> burst + <see cref="DynamicLightSystem.RequestFlash"/>
    /// + <see cref="ScorchDecalSystem.RequestScorch"/> (bundle 2, built for this). Pooled disc GameObjects under a
    /// private root, pruned every frame; a pruned geyser (teardown / relevancy drop) is SILENT.
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    [UpdateInGroup(typeof(PresentationSystemGroup))]
    public partial class GeyserTelegraphSystem : SystemBase
    {
        static readonly Color DiscColor = new Color(2.6f, 0.35f, 2.4f);  // hot blight magenta-purple (danger + biome id)
        static readonly Color EruptColor = new Color(2.9f, 0.5f, 3.2f);  // brighter burst
        static readonly int ColorId = Shader.PropertyToID("_Color");

        Transform _fxRoot;
        Material _discMat;
        Material _burstMat;
        Mesh _discMesh;
        ParticleSystem _eruptFx;
        AudioClip _eruptClip;
        MaterialPropertyBlock _mpb;

        readonly Dictionary<Entity, GameObject> _discs = new();
        readonly Dictionary<Entity, uint> _armed = new();      // NextEruptTick we've seen counting down for
        readonly Dictionary<Entity, uint> _lastFired = new();  // NextEruptTick we last fired the burst for (latch)
        readonly HashSet<Entity> _seen = new();
        readonly List<Entity> _stale = new();

        protected override void OnCreate()
        {
            _eruptClip = MakeClip("geyser_erupt", 90f, 300f, 0.30f, 0.55f, noise: true, decay: 5f);
            _mpb = new MaterialPropertyBlock();
        }

        protected override void OnStartRunning()
        {
            if (_fxRoot != null) return;
            _fxRoot = new GameObject("~GeyserTelegraphFX").transform;
            _discMat = MakeParticleMaterial("GeyserDisc");
            _discMat.color = DiscColor;
            _discMesh = BuildDisc(40);
            _burstMat = MakeParticleMaterial("GeyserErupt");
            _eruptFx = MakeBurst(_fxRoot, "GeyserErupt", _burstMat, EruptColor, 0.18f, 8f, 0.5f, 256, -0.15f, 0.25f, 0.25f);
        }

        protected override void OnDestroy()
        {
            if (_fxRoot != null) Object.Destroy(_fxRoot.gameObject);
            if (_discMat != null) Object.Destroy(_discMat);
            if (_burstMat != null) Object.Destroy(_burstMat);
            if (_discMesh != null) Object.Destroy(_discMesh);
        }

        protected override void OnUpdate()
        {
            if (_fxRoot == null || _discMat == null) return;
            if (!SystemAPI.TryGetSingleton<NetworkTime>(out var nt) || !nt.ServerTick.IsValid) return;
            var serverTick = nt.ServerTick;

            EntityManager.CompleteDependencyBeforeRO<Geyser>();
            EntityManager.CompleteDependencyBeforeRO<LocalTransform>();

            _seen.Clear();
            foreach (var (geyser, xf, e) in
                     SystemAPI.Query<RefRO<Geyser>, RefRO<LocalTransform>>().WithEntityAccess())
            {
                uint next = geyser.ValueRO.NextEruptTick;
                if (next == 0u) continue;                       // unstamped -> no telegraph yet (born-correct pending)
                var untilTick = new NetworkTick(next);
                if (!untilTick.IsValid) continue;
                _seen.Add(e);

                int lead = untilTick.TicksSince(serverTick);    // >0 = erupt in the future, <=0 = erupt now/past
                float3 pos = xf.ValueRO.Position;

                if (lead > 0)
                {
                    _armed[e] = next;                           // arm this eruption while it counts down
                }
                else // lead <= 0: the erupt tick has arrived / passed
                {
                    bool armedForThis = _armed.TryGetValue(e, out var av) && av == next;
                    bool alreadyFired = _lastFired.TryGetValue(e, out var lf) && lf == next;
                    if (armedForThis && !alreadyFired)
                    {
                        // fire ONCE per eruption, on the ServerTick crossing (co-located with the disc completion)
                        EmitTinted(_eruptFx, (Vector3)pos + Vector3.up * 0.3f, 44, EruptColor);
                        DynamicLightSystem.RequestFlash((Vector3)pos, new Color(0.85f, 0.35f, 1f), 1.4f);
                        ScorchDecalSystem.RequestScorch((Vector3)pos, Tuning.GeyserEruptRadius);
                        PlayClip(_eruptClip, (Vector3)pos, 0.7f);
                        _lastFired[e] = next;
                    }
                }

                // Warning disc: grow + pulse over the telegraph window; hidden when dormant or erupted.
                bool showing = lead > 0 && lead <= Tuning.GeyserTelegraphTicks;
                if (showing)
                {
                    float charge = 1f - lead / (float)Tuning.GeyserTelegraphTicks; // 0 at window open -> 1 at erupt
                    if (!_discs.TryGetValue(e, out var go) || go == null)
                    {
                        go = new GameObject("GeyserWarning");
                        go.transform.SetParent(_fxRoot, false);
                        go.AddComponent<MeshFilter>().sharedMesh = _discMesh;
                        var mr = go.AddComponent<MeshRenderer>();
                        mr.sharedMaterial = _discMat;
                        mr.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
                        mr.receiveShadows = false;
                        mr.lightProbeUsage = UnityEngine.Rendering.LightProbeUsage.Off;
                        _discs[e] = go;
                    }
                    if (!go.activeSelf) go.SetActive(true);
                    float radius = Tuning.GeyserEruptRadius * (0.55f + 0.45f * charge);
                    go.transform.position = new Vector3(pos.x, 0.055f, pos.z);
                    go.transform.localScale = new Vector3(radius, 1f, radius);
                    float alpha = 0.14f + 0.5f * charge + 0.12f * Mathf.Abs(Mathf.Sin(UnityEngine.Time.time * 10f));
                    _mpb.SetColor(ColorId, new Color(DiscColor.r, DiscColor.g, DiscColor.b, alpha));
                    go.GetComponent<MeshRenderer>().SetPropertyBlock(_mpb);
                }
                else if (_discs.TryGetValue(e, out var go) && go != null && go.activeSelf)
                {
                    go.SetActive(false); // dormant (lead > window) or just erupted (lead <= 0)
                }
            }

            // Prune despawned geysers (teardown / relevancy drop) — destroy the disc, drop tracking, emit nothing.
            if (_discs.Count > 0)
            {
                _stale.Clear();
                foreach (var kv in _discs) if (!_seen.Contains(kv.Key)) _stale.Add(kv.Key);
                for (int i = 0; i < _stale.Count; i++)
                {
                    if (_discs[_stale[i]] != null) Object.Destroy(_discs[_stale[i]]);
                    _discs.Remove(_stale[i]);
                }
            }
            PruneMap(_armed);
            PruneMap(_lastFired);
        }

        void PruneMap(Dictionary<Entity, uint> dict)
        {
            if (dict.Count == 0) return;
            _stale.Clear();
            foreach (var kv in dict) if (!_seen.Contains(kv.Key)) _stale.Add(kv.Key);
            for (int i = 0; i < _stale.Count; i++) dict.Remove(_stale[i]);
        }
    }
}