using ProjectM.Simulation;
using Unity.Entities;
using Unity.Mathematics;
using UnityEngine;
using static ProjectM.Client.FeedbackFx;

namespace ProjectM.Client
{
    /// <summary>
    /// DR-046 — client-only, observe-only presentation of the room-exit PORTAL made visible. A managed
    /// <see cref="SystemBase"/> in <see cref="PresentationSystemGroup"/> that OBSERVES replicated <see cref="RunInfo"/>
    /// and never mutates the sim. During the <see cref="RunLifecycle.RoomExplore"/> loot window it shows a glowing cyan
    /// pillar (or the authored <see cref="VFXConfig.Portal"/> effect when wired) at the client-derived portal position
    /// so the player has an unmistakable "go here to continue" target; hidden whenever the run isn't in RoomExplore.
    /// Position resolves through the SAME <see cref="RegionMath.ExpeditionPortalPos"/> authority the HUD prompt uses, so
    /// the beacon and the "PRESS E" range always agree. Extracted from CombatFeedbackSystem (owns its own FX-root +
    /// beacon material); no Entity-keyed cache.
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    [UpdateInGroup(typeof(PresentationSystemGroup))]
    public partial class RoomPortalBeaconSystem : SystemBase
    {
        Transform _fxRoot;
        GameObject _portalFx;      // Phase 1: authored portal effect (VFXConfig.Portal) replacing the procedural pillar when wired
        Material _portalMat;       // DR-046: room-exit portal beacon glow (mutated for the pulse; beacon-only mat)
        GameObject _portalBeacon;  // DR-046: pooled world-space "go here" pillar, shown only during RoomExplore

        protected override void OnStartRunning()
        {
            if (_fxRoot != null) return;
            _fxRoot = new GameObject("~RoomPortalBeaconFX").transform;
            _portalMat = MakeParticleMaterial();
            _portalMat.name = "RoomPortal";
            _portalMat.color = new Color(0.25f, 1.2f, 1.55f, 0.85f); // DR-046: HDR cyan portal glow (Phase 0: tamed — 2.6/3.4 bloomed to a white blob)
        }

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

        protected override void OnUpdate()
        {
            UpdatePortalBeacon();
        }

        // DR-046: the room-exit PORTAL made VISIBLE. During the RoomExplore loot window a glowing cyan pillar marks the
        // client-derived portal position so the player has an unmistakable "go here to continue" target — the HUD prompt
        // alone left the exit invisible, so players waited out the ~30s grace timeout ("nothing happens for a while").
        // Client-only, observe-only; one pooled GameObject, hidden whenever the run isn't in RoomExplore. Position
        // resolves through the SAME RegionMath.ExpeditionPortalPos authority the HUD prompt uses -> beacon + "PRESS E"
        // range always agree.
        void UpdatePortalBeacon()
        {
            if (_fxRoot == null || _portalMat == null) return;
            bool inExplore = SystemAPI.TryGetSingleton<RunInfo>(out var ri) && ri.Lifecycle == RunLifecycle.RoomExplore;
            if (!inExplore || !SystemAPI.TryGetSingleton<BaseAnchor>(out var anchor))
            {
                if (_portalBeacon != null && _portalBeacon.activeSelf) _portalBeacon.SetActive(false);
                if (_portalFx != null && _portalFx.activeSelf) _portalFx.SetActive(false);
                return;
            }
            float3 pos = RegionMath.ExpeditionPortalPos(BaseGridMath.PlotCenter(anchor), (byte)(ri.CurrentRoom & 1));
            // Phase 1: prefer the authored portal effect (VFXConfig.Portal, PolygonParticleFX) over the
            // procedural pillar; the pillar remains the asset-free fallback.
            var vfx = VFXConfig.Instance;
            if (vfx != null && vfx.Portal != null)
            {
                if (_portalFx == null)
                {
                    _portalFx = Object.Instantiate(vfx.Portal, _fxRoot, false);
                    _portalFx.name = "~RoomPortalFx";
                }
                _portalFx.transform.position = new Vector3(pos.x, 0f, pos.z); // terrain y=0 (pos.y is the capsule plane)
                if (!_portalFx.activeSelf) _portalFx.SetActive(true);
                if (_portalBeacon != null && _portalBeacon.activeSelf) _portalBeacon.SetActive(false);
                return;
            }
            if (_portalBeacon == null)
            {
                _portalBeacon = GameObject.CreatePrimitive(PrimitiveType.Cylinder);
                _portalBeacon.name = "~RoomPortalBeacon";
                var col = _portalBeacon.GetComponent<Collider>(); if (col != null) Object.Destroy(col); // cosmetic only
                _portalBeacon.transform.SetParent(_fxRoot, false);
                var mr = _portalBeacon.GetComponent<MeshRenderer>();
                mr.sharedMaterial = _portalMat;
                mr.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
                mr.receiveShadows = false;
            }
            if (!_portalBeacon.activeSelf) _portalBeacon.SetActive(true);
            float t = (float)SystemAPI.Time.ElapsedTime;
            float breathe = 0.5f + 0.5f * math.sin(t * 3.5f);
            var tr = _portalBeacon.transform;
            // Cylinder is 2u tall in local space -> scale.y=2.2 gives a 4.4u pillar; lift the centre so the base sits
            // on the TERRAIN (y=0) — pos.y is the CC capsule-center plane (GridOrigin.y=1), 1 u above the ground.
            tr.position = new Vector3(pos.x, 2.2f, pos.z);
            tr.localScale = new Vector3(0.9f + 0.12f * breathe, 2.2f, 0.9f + 0.12f * breathe);
            _portalMat.color = new Color(0.25f, 1.2f, 1.55f, 0.45f + 0.3f * breathe); // glow throb (beacon-only mat; Phase 0: tamed + slimmed — the fat 6u pillar bloomed to a white egg swallowing the prompt)
        }
    }
}