using System.Collections;
using System.Collections.Generic;
using UnityEngine.Pool;

namespace DanieleMarotta.RiversongCodeShowcase
{
    public class RawResourcesState : IEnumerable<ResourceNode>
    {
        private const int SpatialLookupCellSize = 5;

        private Dictionary<int, ResourceNode> _resourceNodesById = new();

        private Dictionary<int, SpatialLookup<(int, bool)>> _spatialLookups = new();

        public int Count => _resourceNodesById.Count;

        public void AddResourceNode(in ResourceNode node)
        {
            _resourceNodesById.Add(node.Id, node);
            GetLookup(node.Elevation).Add((node.Id, node.CanBeDeleted), TileRect.OneTile(node.Tile), node.Id);
        }

        public bool Exists(int id)
        {
            return _resourceNodesById.ContainsKey(id);
        }

        public bool TryGetResourceNode(int id, out ResourceNode node)
        {
            return _resourceNodesById.TryGetValue(id, out node);
        }

        public void GetResourceNodes(TileRect rect, int elevation, List<(int, bool)> resourceNodeIds)
        {
            GetLookup(elevation).Find(rect, resourceNodeIds);
        }

        public bool DeleteResourceNode(int id, int elevation, out ResourceNode resourceNode)
        {
            var result = _resourceNodesById.Remove(id, out resourceNode);
            if (result) GetLookup(elevation).Remove(TileRect.OneTile(resourceNode.Tile), id);
            return result;
        }

        public void DeleteResourceNodes(TileRect rect, int elevation, List<ResourceNode> deletedResourceNodes = null)
        {
            using var removeIdsScope = ListPool<(int, bool)>.Get(out var removeIds);
            GetLookup(elevation)
                .RemoveAll(
                    rect,
                    value =>
                    {
                        var (_, canBeDeleted) = value;
                        return canBeDeleted;
                    },
                    removeIds);

            foreach (var (id, canBeDeleted) in removeIds)
            {
                _resourceNodesById.Remove(id, out var resourceNode);
                deletedResourceNodes?.Add(resourceNode);
            }
        }

        private SpatialLookup<(int, bool)> GetLookup(int elevation)
        {
            if (!_spatialLookups.TryGetValue(elevation, out var lookup))
            {
                lookup = new SpatialLookup<(int, bool)>(SpatialLookupCellSize);
                _spatialLookups.Add(elevation, lookup);
            }
            return lookup;
        }

        public Dictionary<int, ResourceNode>.ValueCollection.Enumerator GetEnumerator()
        {
            return _resourceNodesById.Values.GetEnumerator();
        }

        IEnumerator<ResourceNode> IEnumerable<ResourceNode>.GetEnumerator()
        {
            return GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }
}