using System;
using System.Collections.Generic;
using GeometryTD.Entity.EntityData;
using GeometryTD.Pathfinding;
using UnityEngine;
using UnityEngine.Tilemaps;
using UnityGameFramework.Runtime;

namespace GeometryTD.Entity
{
    public class MapEntity : EntityBase
    {
        private const string PathTileName = "Path";
        private const string FoundationTileName = "Foundation";
        private static readonly Spawner[] EmptySpawners = Array.Empty<Spawner>();

        private readonly List<Vector3Int> _pathCells = new();
        private readonly List<Vector3Int> _foundationCells = new();
        private readonly HashSet<Vector3Int> _pathCellSet = new();
        private readonly HashSet<Vector3Int> _foundationCellSet = new();
        private readonly IMapPathfinder _mapPathfinder = new GridMapPathfinder();
        private readonly List<Vector3Int> _pathCellBuffer = new();
        private readonly Dictionary<Spawner, Vector3Int> _spawnerPathStartByRef = new();
        private readonly Dictionary<Spawner, List<Vector3Int>> _defaultPathCellsBySpawner = new();

        private MapDataRefs _mapDataRefs;
        private MapData _mapData;
        private bool _hasHousePathCell;
        private Vector3Int _housePathCell;

        public IReadOnlyList<Vector3Int> PathCells => _pathCells;
        public IReadOnlyList<Vector3Int> FoundationCells => _foundationCells;
        public Tilemap Tilemap => _mapDataRefs != null ? _mapDataRefs.Tilemap : null;
        public Spawner[] Spawners => _mapDataRefs?.Spawners ?? EmptySpawners;
        public House House => _mapDataRefs?.House;

        public bool IsPathCell(Vector3Int cellPosition)
        {
            return _pathCellSet.Contains(cellPosition);
        }

        public bool IsFoundationCell(Vector3Int cellPosition)
        {
            return _foundationCellSet.Contains(cellPosition);
        }

        public bool TryGetNearestPathCell(Vector3 worldPosition, out Vector3Int pathCell)
        {
            pathCell = default;
            if (_pathCells.Count <= 0 || Tilemap == null)
            {
                return false;
            }

            Vector3Int directCell = Tilemap.WorldToCell(worldPosition);
            if (_pathCellSet.Contains(directCell))
            {
                pathCell = directCell;
                return true;
            }

            float minDistance = float.MaxValue;
            for (int i = 0; i < _pathCells.Count; i++)
            {
                Vector3Int candidate = _pathCells[i];
                float distance = (Tilemap.GetCellCenterWorld(candidate) - worldPosition).sqrMagnitude;
                if (distance >= minDistance)
                {
                    continue;
                }

                minDistance = distance;
                pathCell = candidate;
            }

            return minDistance < float.MaxValue;
        }

        public Vector3 GetPathCellCenterWorld(Vector3Int pathCell)
        {
            return Tilemap != null ? Tilemap.GetCellCenterWorld(pathCell) : Vector3.zero;
        }

        public bool TryGetDefaultPathCells(Spawner spawner, out IReadOnlyList<Vector3Int> pathCells)
        {
            pathCells = null;
            if (spawner == null)
            {
                return false;
            }

            if (!_defaultPathCellsBySpawner.TryGetValue(spawner, out List<Vector3Int> cachedPathCells))
            {
                return false;
            }

            pathCells = cachedPathCells;
            return true;
        }

        public bool TryFindPathCells(Spawner spawner, IReadOnlyCollection<Vector3Int> blockedCells,
            List<Vector3Int> pathResult)
        {
            if (pathResult == null)
            {
                return false;
            }

            pathResult.Clear();
            if (spawner == null || !_hasHousePathCell)
            {
                return false;
            }

            if (!_spawnerPathStartByRef.TryGetValue(spawner, out Vector3Int startCell))
            {
                return false;
            }

            return _mapPathfinder.TryFindPath(_pathCells, startCell, _housePathCell, blockedCells, pathResult);
        }

        public bool TryFindPathWorldPoints(Spawner spawner, IReadOnlyCollection<Vector3Int> blockedCells,
            List<Vector3> worldPathResult)
        {
            if (worldPathResult == null)
            {
                return false;
            }

            worldPathResult.Clear();
            if (Tilemap == null)
            {
                return false;
            }

            if (!TryFindPathCells(spawner, blockedCells, _pathCellBuffer))
            {
                return false;
            }

            foreach (var pos in _pathCellBuffer)
            {
                worldPathResult.Add(GetPathCellCenterWorld(pos));
            }

            return true;
        }

        protected override void OnInit(object userData)
        {
            base.OnInit(userData);

            _mapDataRefs = GetComponent<MapDataRefs>();
            if (_mapDataRefs == null)
            {
                Log.Error("MapDataRefs is missing on map entity '{0}'.", name);
            }
        }

        protected override void OnShow(object userData)
        {
            base.OnShow(userData);

            _mapData = userData as MapData;
            if (_mapData == null)
            {
                Log.Warning("MapData is invalid for map entity '{0}'.", Id);
            }

            RefreshTiles();
        }

        protected override void OnHide(bool isShutdown, object userData)
        {
            ClearRuntimeData();
            base.OnHide(isShutdown, userData);
        }

        private void RefreshTiles()
        {
            ClearRuntimeData();

            if (_mapDataRefs == null)
            {
                _mapDataRefs = GetComponent<MapDataRefs>();
                if (_mapDataRefs == null)
                {
                    Log.Error("MapDataRefs is missing on map entity '{0}'.", name);
                    return;
                }
            }

            Tilemap tilemap = _mapDataRefs.Tilemap;
            if (tilemap == null)
            {
                Log.Error("Tilemap reference is missing in MapDataRefs on '{0}'.", name);
                return;
            }

            BoundsInt bounds = tilemap.cellBounds;
            foreach (Vector3Int cellPosition in bounds.allPositionsWithin)
            {
                TileBase tile = tilemap.GetTile(cellPosition);
                if (tile == null || string.IsNullOrEmpty(tile.name))
                {
                    continue;
                }

                if (string.Equals(tile.name, PathTileName, StringComparison.Ordinal))
                {
                    _pathCells.Add(cellPosition);
                    _pathCellSet.Add(cellPosition);
                    continue;
                }

                if (string.Equals(tile.name, FoundationTileName, StringComparison.Ordinal))
                {
                    _foundationCells.Add(cellPosition);
                    _foundationCellSet.Add(cellPosition);
                }
            }

            RefreshPathCache();
            Log.Info(
                "Map '{0}' initialized. LevelId={1}, PathCells={2}, FoundationCells={3}, Spawners={4}, House={5}, Routes={6}.",
                name,
                _mapData != null ? _mapData.LevelId : 0,
                _pathCells.Count,
                _foundationCells.Count,
                Spawners.Length,
                House != null ? House.name : "None",
                _defaultPathCellsBySpawner.Count);
        }

        private void RefreshPathCache()
        {
            _hasHousePathCell = false;
            _housePathCell = default;
            _spawnerPathStartByRef.Clear();
            _defaultPathCellsBySpawner.Clear();

            if (House == null)
            {
                Log.Warning("Map '{0}' has no house reference, path cache skipped.", name);
                return;
            }

            if (!TryGetNearestPathCell(House.Position, out _housePathCell))
            {
                Log.Warning("Map '{0}' house position can not map to a valid path cell.", name);
                return;
            }

            _hasHousePathCell = true;
            Spawner[] spawners = Spawners;
            foreach (var spawner in spawners)
            {
                if (spawner == null)
                {
                    continue;
                }

                if (!TryGetNearestPathCell(spawner.Position, out Vector3Int startCell))
                {
                    Log.Warning("Map '{0}' spawner '{1}' can not map to a valid path cell.", name, spawner.name);
                    continue;
                }

                _spawnerPathStartByRef[spawner] = startCell;

                List<Vector3Int> defaultPathCells = new List<Vector3Int>();
                if (!_mapPathfinder.TryFindPath(_pathCells, startCell, _housePathCell, null, defaultPathCells))
                {
                    Log.Warning(
                        "Map '{0}' spawner '{1}' has no path to house cell {2}.",
                        name,
                        spawner.name,
                        _housePathCell);
                    continue;
                }

                _defaultPathCellsBySpawner[spawner] = defaultPathCells;
            }
        }

        private void ClearRuntimeData()
        {
            _pathCells.Clear();
            _foundationCells.Clear();
            _pathCellSet.Clear();
            _foundationCellSet.Clear();
            _pathCellBuffer.Clear();
            _hasHousePathCell = false;
            _housePathCell = default;
            _spawnerPathStartByRef.Clear();
            _defaultPathCellsBySpawner.Clear();
        }
    }
}