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, tower bolts from the towers' attack events. 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;

        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;

        sealed class Bolt
        {
            public LineRenderer Line;
            public float Age;
            public LuneUnitView Target;
            public Vector3 From;
        }

        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;
            if (match.Combat != _combat)
            {
                foreach (LuneUnitView view in _units.Values)
                    Destroy(view.gameObject);
                _units.Clear();
                _towerSerials.Clear();
                _combat = match.Combat;
            }
            bool showUnits = _combat != null && Driver.Runner.Current != LuneMatchRunner.Stage.Planning;
            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);
            _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 (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)];
            line.widthMultiplier = view.Tier == "base" ? .22f : .16f;
            line.positionCount = 2;
            line.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
            _bolts.Add(new Bolt { Line = line, Target = target, From = view.Muzzle });
        }

        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;
                }
                bolt.Line.SetPosition(0, bolt.From);
                bolt.Line.SetPosition(1, bolt.Target.AimPoint);
            }
        }
    }
}