using System;
using System.Collections.Generic;
using System.Linq;
using Encompass.Exceptions;

namespace Encompass
{
    internal class DrawLayerManager
    {
        private readonly SortedList<int, int> _layerOrder = new SortedList<int, int>();

        private readonly Dictionary<int, ComponentStore> _layerIndexToComponentStore = new Dictionary<int, ComponentStore>(512);
        private readonly Dictionary<int, HashSet<GeneralRenderer>> _layerIndexToGeneralRenderers = new Dictionary<int, HashSet<GeneralRenderer>>(512);

        private readonly Dictionary<Type, Dictionary<int, int>> _typeToEntityToLayer = new Dictionary<Type, Dictionary<int, int>>(512);
        private readonly Dictionary<Type, int> _typeToIndex;
        public IEnumerable<int> LayerOrder { get { return _layerOrder.Values; } }

        public DrawLayerManager(Dictionary<Type, int> typeToIndex)
        {
            _typeToIndex = typeToIndex;
            RegisterDrawLayer(0);
        }

        public void RegisterDrawLayer(int layer)
        {
            if (!_layerIndexToComponentStore.ContainsKey(layer))
            {
                _layerOrder.Add(layer, layer);
                _layerIndexToGeneralRenderers.Add(layer, new HashSet<GeneralRenderer>());
                _layerIndexToComponentStore.Add(layer, new ComponentStore(_typeToIndex));
            }
        }

        public void RegisterOrderedDrawable<TComponent>() where TComponent : struct, IComponent
        {
            if (!_typeToEntityToLayer.ContainsKey(typeof(TComponent)))
            {
                _typeToEntityToLayer.Add(typeof(TComponent), new Dictionary<int, int>(128));
            }

            foreach (var pair in _layerIndexToComponentStore)
            {
                pair.Value.RegisterComponentType<TComponent>();
            }
        }

        public void RegisterGeneralRendererWithLayer(GeneralRenderer renderer, int layer)
        {
            RegisterDrawLayer(layer);
            var set = _layerIndexToGeneralRenderers[layer];
            set.Add(renderer);
        }

        public void UnregisterGeneralRendererWithLayer(GeneralRenderer renderer, int layer)
        {
            if (_layerIndexToGeneralRenderers.ContainsKey(layer))
            {
                _layerIndexToGeneralRenderers[layer].Remove(renderer);
            }
        }

        public void AdjustRendererLayer(GeneralRenderer renderer, int oldLayer, int newLayer)
        {
            UnregisterGeneralRendererWithLayer(renderer, oldLayer);
            RegisterGeneralRendererWithLayer(renderer, newLayer);
        }

        public void RegisterComponentWithLayer<TComponent>(int entityID, TComponent component, int layer) where TComponent : struct, IComponent
        {
            if (!_layerIndexToComponentStore.ContainsKey(layer))
            {
                throw new UndefinedLayerException("Layer {0} is not defined. Use WorldBuilder.RegisterDrawLayer to register the layer.", layer);
            }

            if (_typeToEntityToLayer[typeof(TComponent)].ContainsKey(entityID)) { UnRegisterComponentWithLayer<TComponent>(entityID); }

            var set = _layerIndexToComponentStore[layer];
            set.Set<TComponent>(entityID, component);

            _typeToEntityToLayer[typeof(TComponent)].Add(entityID, layer);
        }

        public void UnRegisterComponentWithLayer<TComponent>(int entityID) where TComponent : struct, IComponent
        {
            if (!_typeToEntityToLayer.ContainsKey(typeof(TComponent))) { return; }

            if (_typeToEntityToLayer[typeof(TComponent)].ContainsKey(entityID))
            {
                var layer = _typeToEntityToLayer[typeof(TComponent)][entityID];
                _layerIndexToComponentStore[layer].ForceRemove<TComponent>(entityID);
            }
            _typeToEntityToLayer[typeof(TComponent)].Remove(entityID);
        }

        public void UnRegisterEntityWithLayer(int entityID)
        {
            foreach (var store in _layerIndexToComponentStore.Values)
            {
                store.Remove(entityID);
            }
        }

        public IEnumerable<GeneralRenderer> GeneralRenderersByLayer(int layer)
        {
            return _layerIndexToGeneralRenderers.ContainsKey(layer) ?
                _layerIndexToGeneralRenderers[layer] :
                Enumerable.Empty<GeneralRenderer>();
        }

        public IEnumerable<(int, Type, IComponent)> AllInLayer(int layer)
        {
            return _layerIndexToComponentStore.ContainsKey(layer) ?
                _layerIndexToComponentStore[layer].AllInterfaceTyped() :
                Enumerable.Empty<(int, Type, IComponent)>();
        }
    }
}