using System.Runtime.CompilerServices;

namespace OECS;

/// <summary>
/// Provides query execution logic for <see cref="World"/>.
/// Iterates one sparse set as the driver and probes the remaining sets
/// for membership. The "without" filter is checked after all "with" probes.
///
/// The singleton entity (ID 1) is automatically excluded from all queries.
/// </summary>
internal static class QueryExecutor
{
    private const uint SingletonId = 1;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    private static bool PassesWithoutFilter(ComponentStore store, Entity entity, IReadOnlySet<Type> withoutTypes)
    {
        foreach (var type in withoutTypes)
        {
            var set = store.GetSet(type);
            if (set != null && set.Contains(entity))
                return false;
        }
        return true;
    }

    // ── ForEach overloads ──────────────────────────────────────────────

    public static void ForEach<T1>(
        ComponentStore store,
        QueryDescriptor query,
        ForEachAction<T1> action)
        where T1 : struct
    {
        var set = store.GetSet(typeof(T1)) as SparseSet<T1>;
        if (set == null) return;

        var dense = set.Dense;
        var denseEntities = set.DenseEntities;
        var count = set.Count;

        for (int i = 0; i < count; i++)
        {
            var entity = denseEntities[i];
            if (entity.Id == SingletonId) continue;
            if (!PassesWithoutFilter(store, entity, query.Without))
                continue;
            action(entity, ref dense[i]);
        }
    }

    public static void ForEach<T1, T2>(
        ComponentStore store,
        QueryDescriptor query,
        ForEachAction<T1, T2> action)
        where T1 : struct where T2 : struct
    {
        var set1 = store.GetSet(typeof(T1)) as SparseSet<T1>;
        if (set1 == null) return;
        var set2 = store.GetSet(typeof(T2)) as SparseSet<T2>;
        if (set2 == null) return;

        if (set1.Count <= set2.Count)
        {
            IterateTwo(set1, set2, store, query.Without, action);
        }
        else
        {
            IterateTwoSwapped(set2, set1, store, query.Without, action);
        }
    }

    private static void IterateTwo<TDriver, TOther>(
        SparseSet<TDriver> driveSet,
        SparseSet<TOther> otherSet,
        ComponentStore store,
        IReadOnlySet<Type> withoutTypes,
        ForEachAction<TDriver, TOther> action)
        where TDriver : struct where TOther : struct
    {
        var dense = driveSet.Dense;
        var denseEntities = driveSet.DenseEntities;
        var count = driveSet.Count;

        for (int i = 0; i < count; i++)
        {
            var entity = denseEntities[i];
            if (entity.Id == SingletonId) continue;
            if (!otherSet.Contains(entity)) continue;
            if (!PassesWithoutFilter(store, entity, withoutTypes))
                continue;
            action(entity, ref dense[i], ref otherSet.Get(entity));
        }
    }

    private static void IterateTwoSwapped<TOther, TDriver>(
        SparseSet<TDriver> driveSet,
        SparseSet<TOther> otherSet,
        ComponentStore store,
        IReadOnlySet<Type> withoutTypes,
        ForEachAction<TOther, TDriver> action)
        where TDriver : struct where TOther : struct
    {
        var dense = driveSet.Dense;
        var denseEntities = driveSet.DenseEntities;
        var count = driveSet.Count;

        for (int i = 0; i < count; i++)
        {
            var entity = denseEntities[i];
            if (entity.Id == SingletonId) continue;
            if (!otherSet.Contains(entity)) continue;
            if (!PassesWithoutFilter(store, entity, withoutTypes))
                continue;
            action(entity, ref otherSet.Get(entity), ref dense[i]);
        }
    }

    public static void ForEach<T1, T2, T3>(
        ComponentStore store,
        QueryDescriptor query,
        ForEachAction<T1, T2, T3> action)
        where T1 : struct where T2 : struct where T3 : struct
    {
        var set1 = store.GetSet(typeof(T1)) as SparseSet<T1>;
        if (set1 == null) return;
        var set2 = store.GetSet(typeof(T2)) as SparseSet<T2>;
        if (set2 == null) return;
        var set3 = store.GetSet(typeof(T3)) as SparseSet<T3>;
        if (set3 == null) return;

        var dense = set1.Dense;
        var denseEntities = set1.DenseEntities;
        var count = set1.Count;

        for (int i = 0; i < count; i++)
        {
            var entity = denseEntities[i];
            if (entity.Id == SingletonId) continue;
            if (!set2.Contains(entity)) continue;
            if (!set3.Contains(entity)) continue;
            if (!PassesWithoutFilter(store, entity, query.Without))
                continue;
            action(entity, ref dense[i], ref set2.Get(entity), ref set3.Get(entity));
        }
    }

    public static void ForEach<T1, T2, T3, T4>(
        ComponentStore store,
        QueryDescriptor query,
        ForEachAction<T1, T2, T3, T4> action)
        where T1 : struct where T2 : struct where T3 : struct where T4 : struct
    {
        var set1 = store.GetSet(typeof(T1)) as SparseSet<T1>;
        if (set1 == null) return;
        var set2 = store.GetSet(typeof(T2)) as SparseSet<T2>;
        if (set2 == null) return;
        var set3 = store.GetSet(typeof(T3)) as SparseSet<T3>;
        if (set3 == null) return;
        var set4 = store.GetSet(typeof(T4)) as SparseSet<T4>;
        if (set4 == null) return;

        var dense = set1.Dense;
        var denseEntities = set1.DenseEntities;
        var count = set1.Count;

        for (int i = 0; i < count; i++)
        {
            var entity = denseEntities[i];
            if (entity.Id == SingletonId) continue;
            if (!set2.Contains(entity)) continue;
            if (!set3.Contains(entity)) continue;
            if (!set4.Contains(entity)) continue;
            if (!PassesWithoutFilter(store, entity, query.Without))
                continue;
            action(entity, ref dense[i], ref set2.Get(entity), ref set3.Get(entity), ref set4.Get(entity));
        }
    }

    public static void ForEach<T1, T2, T3, T4, T5>(
        ComponentStore store,
        QueryDescriptor query,
        ForEachAction<T1, T2, T3, T4, T5> action)
        where T1 : struct where T2 : struct where T3 : struct where T4 : struct where T5 : struct
    {
        var set1 = store.GetSet(typeof(T1)) as SparseSet<T1>;
        if (set1 == null) return;
        var set2 = store.GetSet(typeof(T2)) as SparseSet<T2>;
        if (set2 == null) return;
        var set3 = store.GetSet(typeof(T3)) as SparseSet<T3>;
        if (set3 == null) return;
        var set4 = store.GetSet(typeof(T4)) as SparseSet<T4>;
        if (set4 == null) return;
        var set5 = store.GetSet(typeof(T5)) as SparseSet<T5>;
        if (set5 == null) return;

        var dense = set1.Dense;
        var denseEntities = set1.DenseEntities;
        var count = set1.Count;

        for (int i = 0; i < count; i++)
        {
            var entity = denseEntities[i];
            if (entity.Id == SingletonId) continue;
            if (!set2.Contains(entity)) continue;
            if (!set3.Contains(entity)) continue;
            if (!set4.Contains(entity)) continue;
            if (!set5.Contains(entity)) continue;
            if (!PassesWithoutFilter(store, entity, query.Without))
                continue;
            action(entity, ref dense[i], ref set2.Get(entity), ref set3.Get(entity), ref set4.Get(entity), ref set5.Get(entity));
        }
    }

    public static void ForEach<T1, T2, T3, T4, T5, T6>(
        ComponentStore store,
        QueryDescriptor query,
        ForEachAction<T1, T2, T3, T4, T5, T6> action)
        where T1 : struct where T2 : struct where T3 : struct where T4 : struct where T5 : struct where T6 : struct
    {
        var set1 = store.GetSet(typeof(T1)) as SparseSet<T1>;
        if (set1 == null) return;
        var set2 = store.GetSet(typeof(T2)) as SparseSet<T2>;
        if (set2 == null) return;
        var set3 = store.GetSet(typeof(T3)) as SparseSet<T3>;
        if (set3 == null) return;
        var set4 = store.GetSet(typeof(T4)) as SparseSet<T4>;
        if (set4 == null) return;
        var set5 = store.GetSet(typeof(T5)) as SparseSet<T5>;
        if (set5 == null) return;
        var set6 = store.GetSet(typeof(T6)) as SparseSet<T6>;
        if (set6 == null) return;

        var dense = set1.Dense;
        var denseEntities = set1.DenseEntities;
        var count = set1.Count;

        for (int i = 0; i < count; i++)
        {
            var entity = denseEntities[i];
            if (entity.Id == SingletonId) continue;
            if (!set2.Contains(entity)) continue;
            if (!set3.Contains(entity)) continue;
            if (!set4.Contains(entity)) continue;
            if (!set5.Contains(entity)) continue;
            if (!set6.Contains(entity)) continue;
            if (!PassesWithoutFilter(store, entity, query.Without))
                continue;
            action(entity, ref dense[i], ref set2.Get(entity), ref set3.Get(entity), ref set4.Get(entity), ref set5.Get(entity), ref set6.Get(entity));
        }
    }
}