using System;
using System.Collections.Generic;
using System.Linq;
using CaeMesh;

namespace RBFMorphing
{
    [Serializable]
    public class ElementSet : AbstractClass
    {
        [NonSerialized]
        private readonly FeMesh _mesh;

        [NonSerialized]
        private List<int> _cache;

        public ElementSet(FeMesh mesh, FeElementSet elementSet) : base(EnumMorphMethod.ElementSet)
        {
            if (mesh == null || elementSet == null)
                throw new ArgumentNullException(nameof(ElementSet));

            if (!mesh.ElementSets.ContainsKey(elementSet.Name))
                throw new ArgumentException(nameof(ElementSet));

            _mesh = mesh;
            _cache = new List<int>();
            if (mesh.ElementSets.ContainsKey(elementSet.Name))
            {
                _name = elementSet.Name;
                MakeCache();
            }
        }

        internal void MakeCache()
        {
            _cache.Clear();

            HashSet<int> nodeIds = new HashSet<int>();
            if (_mesh.ElementSets.TryGetValue(_name, out var elementSet))
            {
                foreach (var id in elementSet.Labels)
                {
                    if (!_mesh.Elements.TryGetValue(id, out var element))
                        continue;

                    foreach (var v in element.NodeIds)
                    {
                        nodeIds.Add(v);
                    }
                }
            }

            _cache.AddRange(nodeIds.ToList());
        }

        public override List<FeNode> GetNodes()
        {
            List<FeNode> nodes = new List<FeNode>();

            foreach (var id in _cache.Where(x => _mesh.Nodes.ContainsKey(x)))
            {
                _mesh.Nodes.TryGetValue(id, out var node);
                nodes.Add(node);
            }

            return nodes;
        }

        public override int[] Labels => _cache?.ToArray();

        public override int Length => _cache?.Count ?? 0;
    }
}