using System;
using System.Collections.Generic;
using System.Linq;
using EE = System.Collections.Generic.IEnumerable<Gallium.Entity>;

namespace Gallium
{
    public static class EnumerableEntityExtensions
    {
        public static EE ForEachEntity<T1, T2>(
            this EE entities,
            Func<Entity, T1, T2, Entity> lambda)
        {
            return entities
                .Select(
                    x => !x.Has<T1>() || !x.Has<T2>()
                        ? x
                        : lambda(x, x.Get<T1>(), x.Get<T2>()));
        }

        public static EE ForEachEntity<T1, T2, T3>(
            this EE entities,
            Func<Entity, T1, T2, T3, Entity> lambda)
        {
            return entities
                .Select(
                    x => !x.Has<T1>() || !x.Has<T2>() || !x.Has<T3>()
                        ? x
                        : lambda(x, x.Get<T1>(), x.Get<T2>(), x.Get<T3>()));
        }

        public static EE ForEntities<T1, T2>(
            this EE entities,
            Func<EE, EE> lambda)
        {
            List<Entity> list = entities.ToList();
            EE has = lambda(list.HasComponents<T1, T2>());
            EE hasNot = list.NotComponents<T1, T2>();

            return hasNot.Union(has);
        }

        public static EE ForEntities<T1, T2, T3>(
            this EE entities,
            Func<EE, EE> lambda)
        {
            List<Entity> list = entities.ToList();
            EE has = lambda(list.HasComponents<T1, T2, T3>());
            EE hasNot = list.NotComponents<T1, T2, T3>();

            return hasNot.Union(has);
        }

        public static EE ForEntities<T1, T2, T3, T4>(
            this EE entities,
            Func<EE, EE> lambda)
        {
            List<Entity> list = entities.ToList();
            EE has = lambda(list.HasComponents<T1, T2, T3, T4>());
            EE hasNot = list.NotComponents<T1, T2, T3, T4>();

            return hasNot.Union(has);
        }

        public static EE HasComponents<T1, T2>(this EE entities)
        {
            return entities
                .Where(x => x.Has<T1>() && x.Has<T2>());
        }

        public static EE HasComponents<T1, T2, T3>(this EE entities)
        {
            return entities
                .Where(x => x.Has<T1>() && x.Has<T2>() && x.Has<T3>());
        }

        public static EE HasComponents<T1, T2, T3, T4>(this EE entities)
        {
            return entities
                .Where(
                    x => x.Has<T1>()
                        && x.Has<T2>()
                        && x.Has<T3>()
                        && x.Has<T4>());
        }

        public static EE NotComponents<T1, T2>(this EE entities)
        {
            return entities
                .Where(x => !x.Has<T1>() || !x.Has<T2>());
        }

        public static EE NotComponents<T1, T2, T3>(this EE entities)
        {
            return entities
                .Where(x => !x.Has<T1>() || !x.Has<T2>() || !x.Has<T3>());
        }

        public static EE NotComponents<T1, T2, T3, T4>(this EE entities)
        {
            return entities
                .Where(
                    x => !x.Has<T1>()
                        || !x.Has<T2>()
                        || !x.Has<T3>()
                        || !x.Has<T4>());
        }
    }
}