#include "Core/DescentGameClasses.h"

FDescentGameClassRegistry& FDescentGameClassRegistry::Get()
{
	static FDescentGameClassRegistry Instance;
	return Instance;
}

void FDescentGameClassRegistry::Register(EDescentGameClassSlot Slot, int32 Priority, FName Owner, FClassGetter Getter)
{
	Unregister(Slot, Owner); // the same owner registering a slot again replaces its own entry
	FEntry E;
	E.Slot = Slot;
	E.Priority = Priority;
	E.Owner = Owner;
	E.Getter = MoveTemp(Getter);
	Entries.Add(MoveTemp(E));
}

void FDescentGameClassRegistry::Unregister(EDescentGameClassSlot Slot, FName Owner)
{
	Entries.RemoveAll([&](const FEntry& E) { return E.Slot == Slot && E.Owner == Owner; });
}

const FDescentGameClassRegistry::FEntry* FDescentGameClassRegistry::Pick(EDescentGameClassSlot Slot) const
{
	const FEntry* Best = nullptr;
	for (const FEntry& E : Entries)
	{
		if (E.Slot != Slot)
		{
			continue;
		}
		// Higher priority wins; at equal priority the owner name that sorts first, never the registration order.
		if (!Best || E.Priority > Best->Priority || (E.Priority == Best->Priority && E.Owner.Compare(Best->Owner) < 0))
		{
			Best = &E;
		}
	}
	return Best;
}

UClass* FDescentGameClassRegistry::Resolve(EDescentGameClassSlot Slot) const
{
	const FEntry* E = Pick(Slot);
	return (E && E->Getter) ? E->Getter() : nullptr;
}

FName FDescentGameClassRegistry::ResolveOwner(EDescentGameClassSlot Slot) const
{
	const FEntry* E = Pick(Slot);
	return E ? E->Owner : NAME_None;
}