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

namespace Encompass
{
    internal sealed class ComponentStore
    {
        private Dictionary<Type, TypedComponentStore> _stores = new Dictionary<Type, TypedComponentStore>(512);
        public ComponentBitSet ComponentBitSet { get; private set; }
        private readonly Dictionary<Type, int> _typeToIndex;

        public ComponentStore(Dictionary<Type, int> typeToIndex)
        {
            _typeToIndex = typeToIndex;
            ComponentBitSet = new ComponentBitSet(typeToIndex);
        }

        public void RegisterComponentType<TComponent>() where TComponent : struct
        {
            if (!_stores.ContainsKey(typeof(TComponent)))
            {
                var store = new TypedComponentStore<TComponent>();
                _stores.Add(typeof(TComponent), store);
            }

            if (!_typeToIndex.ContainsKey(typeof(TComponent))) { _typeToIndex.Add(typeof(TComponent), _typeToIndex.Count); }
        }

        private TypedComponentStore<TComponent> Lookup<TComponent>() where TComponent : struct
        {
            return _stores[typeof(TComponent)] as TypedComponentStore<TComponent>;
        }

        public bool Has<TComponent>(int entityID) where TComponent : struct
        {
            return Lookup<TComponent>().Has(entityID);
        }

        public bool Has(Type type, int entityID)
        {
            return _stores[type].Has(entityID);
        }

        public BitSet512 EntityBitArray(int entityID)
        {
            return ComponentBitSet.EntityBitArray(entityID);
        }

        public ref TComponent Get<TComponent>(int entityID) where TComponent : struct
        {
            return ref Lookup<TComponent>().Get(entityID);
        }

        public ref readonly TComponent Singular<TComponent>() where TComponent : struct
        {
            if (!Any<TComponent>()) { throw new NoComponentOfTypeException("No component of type {0} exists", typeof(TComponent).Name); }

            return ref Lookup<TComponent>().Singular();
        }

        public ref readonly Entity SingularEntity<TComponent>() where TComponent : struct
        {
            if (!Any<TComponent>()) { throw new NoComponentOfTypeException("No component of type {0} exists", typeof(TComponent).Name); }

            return ref Lookup<TComponent>().SingularEntity();
        }

        public void Set<TComponent>(int entityID, in TComponent component) where TComponent : struct
        {
            Lookup<TComponent>().Set(entityID, component);
            ComponentBitSet.Set<TComponent>(entityID);
        }

        public bool Set<TComponent>(int entityID, in TComponent component, int priority) where TComponent : struct
        {
            if (Lookup<TComponent>().Set(entityID, component, priority))
            {
                ComponentBitSet.Set<TComponent>(entityID);
                return true;
            }
            return false;
        }

        public bool Remove<TComponent>(int entityID, int priority) where TComponent : struct
        {
            if (Lookup<TComponent>().Remove(entityID, priority))
            {
                ComponentBitSet.RemoveComponent<TComponent>(entityID);
                return true;
            }
            return false;
        }

        public void ForceRemove<TComponent>(int entityID) where TComponent : struct
        {
            Lookup<TComponent>().ForceRemove(entityID);
            ComponentBitSet.RemoveComponent<TComponent>(entityID);
        }

        public void Remove(int entityID)
        {
            foreach (var entry in _stores.Values)
            {
                entry.ForceRemove(entityID);
            }
            ComponentBitSet.RemoveEntity(entityID);
        }

        public bool Any<TComponent>() where TComponent : struct
        {
            return Lookup<TComponent>().Count > 0;
        }

        public ReadOnlySpan<TComponent> All<TComponent>() where TComponent : struct
        {
            return Lookup<TComponent>().AllComponents();
        }

        public IEnumerable<TComponent> AllAsEnumerable<TComponent>() where TComponent : struct
        {
            return Lookup<TComponent>().AllComponentsAsEnumerable();
        }

        public ReadOnlySpan<Entity> AllEntities<TComponent>() where TComponent : struct
        {
            return Lookup<TComponent>().AllEntities();
        }

        public IEnumerable<Entity> AllEntitiesAsEnumerable<TComponent>() where TComponent : struct
        {
            return Lookup<TComponent>().AllEntitiesAsEnumerable();
        }

        public void Clear<TComponent>() where TComponent : struct
        {
            Lookup<TComponent>().Clear();
        }

        public void ClearAllPriorities()
        {
            foreach (var store in _stores.Values)
            {
                store.ClearPriorities();
            }
        }

        public void ClearAll()
        {
            ComponentBitSet.Clear();
            foreach (var store in _stores.Values)
            {
                store.Clear();
            }
        }

        public void SwapWith(ComponentStore other)
        {
            (_stores, other._stores) = (other._stores, _stores);
            (ComponentBitSet, other.ComponentBitSet) = (other.ComponentBitSet, ComponentBitSet);
        }

        public void UpdateUsing(ComponentDeltaStore delta)
        {
            foreach (var replayer in delta.CurrentReplayers)
            {
                replayer.Replay(this);
            }
        }
    }
}