using System.Collections.Generic;
using Luneraria.Core;
using UnityEngine;

namespace Luneraria.View
{
    /// <summary>
    /// Shows the driver's match (U2C): unit views per combat, building looks from the authoritative
    /// HP with the Ancients' health bars, tower bolts from the towers' attack events, and the
    /// Schlundkrone resting in its grotto while the grotto is open (U3, from lune_grotto_view.gd).
    /// Runs after the driver in the same frame and only reads the core.
    /// </summary>
    [DefaultExecutionOrder(100)]
    public sealed class LuneMatchView : MonoBehaviour
    {
        public LuneMatchDriver Driver;
        public LuneUnitLibrary Library;
        public Camera ViewCamera;
        /// <summary>
        /// Planning only: the human's draft army in its formation (set by the game controller, U3;
        /// Godot _rebuild_preview). Bot matches leave it empty and show no units while planning.
        /// </summary>
        public LuneCombat Preview;

        readonly Dictionary<int, LuneUnitView> _units = new Dictionary<int, LuneUnitView>();
        readonly Dictionary<string, LuneBuildingView> _buildings = new Dictionary<string, LuneBuildingView>();
        readonly Dictionary<string, int> _towerSerials = new Dictionary<string, int>();
        readonly List<Bolt> _bolts = new List<Bolt>();
        LuneCombat _combat;
        Transform _unitRoot;
        bool _synced;
        GameObject _restingBoss;
        readonly Dictionary<string, AncientBar> _ancientBars = new Dictionary<string, AncientBar>();

        /// <summary>Health bar over an Ancient (lune_ancient_view.gd _build_bar: 3.4 m wide, 11.2 m up).</summary>
        sealed class AncientBar
        {
            public Transform Root;
            public Transform Fill;
        }

        public const float AncientBarWidth = 3.4f;
        public const float AncientBarHeight = 11.2f;
        /// <summary>Godot BOSS_LOCAL and view scale of the resting boss on its dais.</summary>
        public const float RestingBossScale = 1.7f;

        /// <summary>The resting Schlundkrone (tests); null until the grotto was first open.</summary>
        public GameObject RestingBoss { get { return _restingBoss; } }
        sealed class Bolt
        {
            public LineRenderer Line;
            public float Age;
            public LuneUnitView Target;
            public Vector3 From;
            public int Team;
        }

        /// <summary>U5 spark: fat at the muzzle, a bright core, a fine tip.</summary>
        static readonly AnimationCurve BoltWidth = new AnimationCurve(
            new Keyframe(0f, .35f), new Keyframe(.55f, 1f), new Keyframe(1f, 0f));

        static Gradient BoltGradient(Color light, float alpha)
        {
            var gradient = new Gradient();
            gradient.SetKeys(
                new[] { new GradientColorKey(light, 0f), new GradientColorKey(Color.Lerp(light, Color.white, .55f), .55f), new GradientColorKey(light, 1f) },
                new[] { new GradientAlphaKey(alpha, 0f), new GradientAlphaKey(alpha, 1f) });
            return gradient;
        }

        public IEnumerable<LuneUnitView> Units { get { return _units.Values; } }
        /// <summary>Main-thread cost of the last frame's view update (milliseconds).</summary>
        public double LastSyncMs { get; private set; }
        readonly System.Diagnostics.Stopwatch _clock = new System.Diagnostics.Stopwatch();

        public LuneBuildingView Building(string id)
        {
            _buildings.TryGetValue(id, out LuneBuildingView view);
            return view;
        }

        void Start()
        {
            foreach (LuneBuildingView building in FindObjectsByType<LuneBuildingView>(FindObjectsSortMode.None))
                _buildings[building.BuildingId] = building;
            _unitRoot = new GameObject("Units").transform;
            if (ViewCamera == null)
                ViewCamera = Camera.main;
        }

        void LateUpdate()
        {
            if (Driver == null || Driver.Runner == null)
                return;
            _clock.Restart();
            LuneMatch match = Driver.Runner.Match;
            float dt = Time.deltaTime;
            // Planning shows the preview when there is one (human seat); a bot match keeps the last
            // combat's figures standing, unsynced, as in Godot.
            bool planning = Driver.Runner.Current == LuneMatchRunner.Stage.Planning;
            LuneCombat shown = planning && Preview != null ? Preview : match.Combat;
            if (shown != _combat)
            {
                foreach (LuneUnitView view in _units.Values)
                    Destroy(view.gameObject);
                _units.Clear();
                _towerSerials.Clear();
                _combat = shown;
            }
            bool showUnits = _combat != null && (!planning || _combat == Preview);
            float alpha = Driver.Runner.Current == LuneMatchRunner.Stage.Combat ? (float)Driver.Runner.Clock.Alpha : 1f;
            if (showUnits)
            {
                foreach (LuneUnit unit in _combat.Units)
                {
                    if (!unit.IsMobile())
                        continue;
                    if (!_units.TryGetValue(unit.Id, out LuneUnitView view))
                    {
                        view = new GameObject().AddComponent<LuneUnitView>();
                        view.transform.SetParent(_unitRoot, false);
                        view.Bind(unit, Library);
                        _units[unit.Id] = view;
                    }
                    view.Sync(alpha, dt, ViewCamera != null ? ViewCamera.transform : null);
                }
            }
            SyncBuildings(match);
            SyncBolts(dt);
            SyncRestingBoss(match);
            _synced = true;
            LastSyncMs = _clock.Elapsed.TotalMilliseconds;
        }

        void SyncBuildings(LuneMatch match)
        {
            bool fighting = _combat != null && match.Phase == Phase.Combat;
            foreach (BuildingDef definition in match.Map.Buildings)
            {
                if (!_buildings.TryGetValue(definition.Id, out LuneBuildingView view))
                    continue;
                double hp = match.BuildingHp[definition.Id];
                LuneUnit unit = null;
                if (_combat != null && _combat.Buildings.TryGetValue(definition.Id, out unit) && fighting)
                    hp = unit.Hp;
                view.SetHealth((float)hp, (float)definition.MaxHp, _synced);
                if (view.Tier == "core")
                    SyncAncientBar(view, (float)hp, (float)definition.MaxHp);
                if (unit != null && unit.Kind == "tower" && _combat != null)
                    TowerAttack(view, unit);
            }
        }

        void TowerAttack(LuneBuildingView view, LuneUnit tower)
        {
            _towerSerials.TryGetValue(tower.BuildingId, out int last);
            _towerSerials[tower.BuildingId] = tower.AttackSerial;
            if (tower.AttackSerial == last || last == 0 && tower.AttackSerial == 0)
                return;
            if (tower.Target == null || !_units.TryGetValue(tower.Target.Id, out LuneUnitView target))
                return;
            var line = new GameObject("Bolt").AddComponent<LineRenderer>();
            line.transform.SetParent(_unitRoot, false);
            line.sharedMaterial = Library.Bolt[Mathf.Clamp(view.Team, 0, 2)];
            // U5: a drawn-out spark rather than a bare tube (G3 tower shot).
            line.widthMultiplier = view.Tier == "base" ? .28f : .18f;
            line.widthCurve = BoltWidth;
            int team = Mathf.Clamp(view.Team, 0, 2);
            line.colorGradient = BoltGradient(Library.BoltLight[team], 1f);
            line.numCapVertices = 4;
            line.numCornerVertices = 2;
            line.textureMode = LineTextureMode.Tile;
            line.positionCount = 3;
            line.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
            line.receiveShadows = false;
            _bolts.Add(new Bolt { Line = line, Target = target, From = view.Muzzle, Team = team });
        }

        /// <summary>The bar shows while the Ancient is damaged and standing, always facing the camera.</summary>
        void SyncAncientBar(LuneBuildingView view, float hp, float maxHp)
        {
            float fraction = Mathf.Clamp01(hp / Mathf.Max(1f, maxHp));
            bool visible = hp > 0f && fraction < .999f;
            _ancientBars.TryGetValue(view.BuildingId, out AncientBar bar);
            if (bar == null)
            {
                if (!visible || Library == null || Library.Quad == null)
                    return;
                bar = new AncientBar { Root = new GameObject("AncientBar").transform };
                bar.Root.SetParent(view.transform, false);
                bar.Root.localPosition = new Vector3(0f, AncientBarHeight, 0f);
                Transform back = Quad(bar.Root, "Back", Library.BarBack);
                back.localScale = new Vector3(AncientBarWidth + .1f, .26f, 1f);
                bar.Fill = Quad(bar.Root, "Fill", Library.AncientBarFill[Mathf.Clamp(view.Team, 0, 1)]);
                _ancientBars[view.BuildingId] = bar;
            }
            if (bar.Root.gameObject.activeSelf != visible)
                bar.Root.gameObject.SetActive(visible);
            if (!visible)
                return;
            bar.Fill.localScale = new Vector3(AncientBarWidth * Mathf.Max(.001f, fraction), .17f, 1f);
            bar.Fill.localPosition = new Vector3(-AncientBarWidth * .5f * (1f - fraction), 0f, -.001f);
            if (ViewCamera != null)
                bar.Root.rotation = ViewCamera.transform.rotation;
        }

        Transform Quad(Transform parent, string label, Material material)
        {
            var go = new GameObject(label);
            go.transform.SetParent(parent, false);
            go.AddComponent<MeshFilter>().sharedMesh = Library.Quad;
            var renderer = go.AddComponent<MeshRenderer>();
            renderer.sharedMaterial = material;
            renderer.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
            renderer.receiveShadows = false;
            return go.transform;
        }

        /// <summary>
        /// The Schlundkrone rests on its dais while the grotto is open and no boss unit stands there
        /// (lune_grotto_view.gd: state AVAILABLE without a fighter): the figure the fight uses,
        /// neutral, facing the arena and the two stairs, in its idle clip. The grotto's light
        /// states (runes, crystals, motes) are not ported yet.
        /// </summary>
        void SyncRestingBoss(LuneMatch match)
        {
            LuneUnit fighter = match.Phase == Phase.Combat && match.Combat != null ? match.Combat.GrottoBoss : null;
            bool visible = match.Boss.Claim == null && match.GrottoAvailable() && fighter == null;
            if (visible && _restingBoss == null)
                _restingBoss = MakeRestingBoss(match.Map);
            if (_restingBoss != null && _restingBoss.activeSelf != visible)
                _restingBoss.SetActive(visible);
        }

        GameObject MakeRestingBoss(LuneMap map)
        {
            LuneUnitLibrary.UnitModel model = Library != null ? Library.Find(Library.BossModel) : null;
            if (model == null || model.Prefab == null)
                return null;
            var root = new GameObject("RestingBoss");
            root.transform.SetParent(transform, false);
            Vec2 at = map.GrottoBossPoint();
            root.transform.position = LuneSpace.World(at, (Library.Ground != null ? Library.Ground.StandHeight(at) : 0f) + .03f);
            root.transform.rotation = LuneSpace.Facing(System.Math.Atan2(LuneMap.Axis.X, LuneMap.Axis.Y));
            GameObject figure = Instantiate(model.Prefab, root.transform, false);
            figure.name = "Model";
            figure.SetActive(true);
            figure.transform.localScale = Vector3.one * RestingBossScale;
            Library.Materials.Dress(figure, 2);
            var animator = figure.GetComponentInChildren<Animator>();
            if (animator != null && model.Controller != null)
            {
                animator.runtimeAnimatorController = model.Controller;
                animator.applyRootMotion = false;
                if (animator.HasState(0, Animator.StringToHash("idle")))
                    animator.Play("idle", 0, 0f);
            }
            return root;
        }

        void SyncBolts(float dt)
        {
            for (int i = _bolts.Count - 1; i >= 0; i--)
            {
                Bolt bolt = _bolts[i];
                bolt.Age += dt;
                if (bolt.Age > .25f || bolt.Target == null)
                {
                    Destroy(bolt.Line.gameObject);
                    _bolts.RemoveAt(i);
                    continue;
                }
                Vector3 to = bolt.Target.AimPoint;
                // U5: three points bow the spark slightly toward the camera; fade over its life.
                Vector3 mid = Vector3.Lerp(bolt.From, to, .55f);
                if (ViewCamera != null)
                    mid += ViewCamera.transform.up * .12f;
                bolt.Line.SetPosition(0, bolt.From);
                bolt.Line.SetPosition(1, mid);
                bolt.Line.SetPosition(2, to);
                float fade = 1f - Mathf.Clamp01((bolt.Age - .12f) / .13f);
                bolt.Line.colorGradient = BoltGradient(Library.BoltLight[bolt.Team], fade);
            }
        }
    }
}