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

namespace Encompass
{
    class ComponentMessageManager
    {
        private readonly ComponentStore componentStore = new ComponentStore();

        private readonly ComponentStore existingComponentStore = new ComponentStore();
        private readonly ComponentStore pendingComponentStore = new ComponentStore();

        private readonly Dictionary<Type, Dictionary<Entity, int>> typeToEntityToPendingComponentPriority = new Dictionary<Type, Dictionary<Entity, int>>();

        internal void ClearMessages()
        {
            componentStore.ClearAll();
            existingComponentStore.ClearAll();
            pendingComponentStore.ClearAll();

            foreach (var dictionary in typeToEntityToPendingComponentPriority.Values)
            {
                dictionary.Clear();
            }
        }

        internal void AddExistingComponentMessage<TComponent>(ComponentMessage<TComponent> componentMessage) where TComponent : struct, IComponent
        {
            RegisterExistingOrPendingComponentMessage(componentMessage.entity, componentMessage.component);

            existingComponentStore.Set(componentMessage.entity, componentMessage.component);
        }

        internal void AddPendingComponentMessage<TComponent>(PendingComponentMessage<TComponent> pendingComponentMessage) where TComponent : struct, IComponent
        {
            RegisterExistingOrPendingComponentMessage(pendingComponentMessage.entity, pendingComponentMessage.component);

            pendingComponentStore.Set(pendingComponentMessage.entity, pendingComponentMessage.component, pendingComponentMessage.priority);
        }

        private void RegisterExistingOrPendingComponentMessage<TComponent>(Entity entity, TComponent component) where TComponent : struct, IComponent
        {
            componentStore.Set(entity, component);
        }

        // general component reads by type

        internal IEnumerable<(Entity, TComponent)> ReadExistingAndPendingComponentsByType<TComponent>() where TComponent : struct, IComponent
        {
            return componentStore.All<TComponent>();
        }

        internal IEnumerable<(Entity, TComponent)> ReadExistingComponentsByType<TComponent>() where TComponent : struct, IComponent
        {
            return existingComponentStore.All<TComponent>();
        }

        internal IEnumerable<(Entity, TComponent)> ReadPendingComponentsByType<TComponent>() where TComponent : struct, IComponent
        {
            return pendingComponentStore.All<TComponent>();
        }

        // singular component reads by type

        internal (Entity, TComponent) ReadFirstExistingOrPendingComponentByType<TComponent>() where TComponent : struct, IComponent
        {
            if (!SomeExistingOrPendingComponent<TComponent>()) { throw new Exceptions.NoComponentOfTypeException($"No Component with type {typeof(TComponent)} exists"); }
            return ReadExistingAndPendingComponentsByType<TComponent>().First();
        }

        internal (Entity, TComponent) ReadFirstExistingComponentByType<TComponent>() where TComponent : struct, IComponent
        {
            if (!SomeExistingComponent<TComponent>()) { throw new Exceptions.NoComponentOfTypeException($"No Component with type {typeof(TComponent)} exists"); }
            return ReadExistingComponentsByType<TComponent>().First();
        }

        internal (Entity, TComponent) ReadFirstPendingComponentByType<TComponent>() where TComponent : struct, IComponent
        {
            if (!SomeExistingComponent<TComponent>()) { throw new Exceptions.NoComponentOfTypeException($"No Component with type {typeof(TComponent)} exists"); }
            return ReadPendingComponentsByType<TComponent>().First();
        }

        // check if some component of type exists in the world

        internal bool SomeExistingOrPendingComponent<TComponent>() where TComponent : struct, IComponent
        {
            return componentStore.Any<TComponent>();
        }

        internal bool SomeExistingComponent<TComponent>() where TComponent : struct, IComponent
        {
            return existingComponentStore.Any<TComponent>();
        }

        internal bool SomePendingComponent<TComponent>() where TComponent : struct, IComponent
        {
            return pendingComponentStore.Any<TComponent>();
        }

        // read components by entity and type

        internal TComponent ReadExistingComponentByEntityAndType<TComponent>(Entity entity) where TComponent : struct, IComponent
        {
            return existingComponentStore.Get<TComponent>(entity);
        }

        internal TComponent ReadPendingComponentByEntityAndType<TComponent>(Entity entity) where TComponent : struct, IComponent
        {
            return pendingComponentStore.Get<TComponent>(entity);
        }

        // check if entity has component of type

        internal bool HasExistingOrPendingComponent<TComponent>(Entity entity) where TComponent : struct, IComponent
        {
            return componentStore.Has<TComponent>(entity);
        }

        internal bool HasExistingOrPendingComponent(Entity entity, Type type)
        {
            return componentStore.Has(type, entity);
        }

        internal bool HasExistingComponent<TComponent>(Entity entity) where TComponent : struct, IComponent
        {
            return existingComponentStore.Has<TComponent>(entity);
        }

        internal bool HasExistingComponent(Entity entity, Type type)
        {
            return existingComponentStore.Has(type, entity);
        }

        internal bool HasPendingComponent<TComponent>(Entity entity) where TComponent : struct, IComponent
        {
            return pendingComponentStore.Has<TComponent>(entity);
        }

        internal bool HasPendingComponent(Entity entity, Type type)
        {
            return pendingComponentStore.Has(type, entity);
        }
    }
}