//
//  Nexus+Family.swift
//  FirebladeECS
//
//  Created by Christian Treffs on 13.10.17.
//

extension Nexus {
    public final var numFamilies: Int {
        familyMembersByTraits.keys.count
    }

    public func canBecomeMember(_ entity: Entity, in traits: FamilyTraitSet) -> Bool {
        guard let componentIds = componentIdsByEntity[entity.identifier] else {
            assertionFailure("no component set defined for entity: \(entity)")
            return false
        }
        return traits.isMatch(components: componentIds)
    }

    public func members(withFamilyTraits traits: FamilyTraitSet) -> UnorderedSparseSet<EntityIdentifier, EntityIdentifier.Identifier> {
        familyMembersByTraits[traits] ?? UnorderedSparseSet<EntityIdentifier, EntityIdentifier.Identifier>()
    }

    public func isMember(_ entity: Entity, in family: FamilyTraitSet) -> Bool {
        isMember(entity.identifier, in: family)
    }

    public func isMember(_ entityId: EntityIdentifier, in family: FamilyTraitSet) -> Bool {
        isMember(entity: entityId, inFamilyWithTraits: family)
    }

    public func isMember(entity entityId: EntityIdentifier, inFamilyWithTraits traits: FamilyTraitSet) -> Bool {
        members(withFamilyTraits: traits).contains(entityId.id)
    }
}