package net.minecraft.server.permissions;

import com.google.common.annotations.VisibleForTesting;
import it.unimi.dsi.fastutil.objects.ReferenceArraySet;
import it.unimi.dsi.fastutil.objects.ReferenceSet;

public class PermissionSetUnion implements PermissionSet {
	private final ReferenceSet<PermissionSet> permissions = new ReferenceArraySet<>();

	PermissionSetUnion(final PermissionSet first, final PermissionSet second) {
		this.permissions.add(first);
		this.permissions.add(second);
		this.ensureNoUnionsWithinUnions();
	}

	private PermissionSetUnion(final ReferenceSet<PermissionSet> oldPermissions, final PermissionSet other) {
		this.permissions.addAll(oldPermissions);
		this.permissions.add(other);
		this.ensureNoUnionsWithinUnions();
	}

	private PermissionSetUnion(final ReferenceSet<PermissionSet> oldPermissions, final ReferenceSet<PermissionSet> other) {
		this.permissions.addAll(oldPermissions);
		this.permissions.addAll(other);
		this.ensureNoUnionsWithinUnions();
	}

	@Override
	public boolean hasPermission(final Permission permission) {
		for (PermissionSet set : this.permissions) {
			if (set.hasPermission(permission)) {
				return true;
			}
		}

		return false;
	}

	@Override
	public PermissionSet union(final PermissionSet other) {
		return other instanceof PermissionSetUnion otherUnion
			? new PermissionSetUnion(this.permissions, otherUnion.permissions)
			: new PermissionSetUnion(this.permissions, other);
	}

	@VisibleForTesting
	public ReferenceSet<PermissionSet> getPermissions() {
		return new ReferenceArraySet<>(this.permissions);
	}

	private void ensureNoUnionsWithinUnions() {
		for (PermissionSet set : this.permissions) {
			if (set instanceof PermissionSetUnion) {
				throw new IllegalArgumentException("Cannot have PermissionSetUnion within another PermissionSetUnion");
			}
		}
	}
}