/*
 * Copyright (c) 2018 Pantheon Technologies, s.r.o.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.yangtools.yang.xpath.api;

import static java.util.Objects.requireNonNull;

import com.google.common.annotations.Beta;
import org.eclipse.jdt.annotation.Nullable;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.common.UnresolvedQName;

/**
 * An XPath QName expression. This is an exact QName, which cannot be converted to a string literal compatible with
 * XPath string representation, because it does not define a prefix/namespace mapping. It represents a strong binding
 * to a particular namespace at a particular revision.
 *
 * <p>
 * Parsers and users of this package are encouraged to use this class in place of {@link YangLiteralExpr} where
 * appropriate, as it retains type safety and more semantic context.
 *
 * @author Robert Varga
 */
@Beta
public abstract sealed class YangQNameExpr implements YangExpr, QNameReferent {
    public static final class Resolved extends YangQNameExpr implements ResolvedQNameReferent {
        private static final long serialVersionUID = 1L;

        private final QName qname;

        Resolved(final QName qname) {
            this.qname = requireNonNull(qname);
        }

        @Override
        public QName getQName() {
            return qname;
        }

        @Override
        public int hashCode() {
            return qname.hashCode();
        }

        @Override
        public boolean equals(final @Nullable Object obj) {
            return this == obj || obj instanceof Resolved other && qname.equals(other.qname);
        }

        @Override
        public String toString() {
            return qname.toString();
        }
    }

    public static final class Unresolved extends YangQNameExpr implements UnresolvedQNameReferent {
        private static final long serialVersionUID = 1L;

        private final UnresolvedQName qname;

        Unresolved(final UnresolvedQName qname) {
            this.qname = requireNonNull(qname);
        }

        @Override
        public UnresolvedQName getQName() {
            return qname;
        }

        @Override
        public int hashCode() {
            return qname.hashCode();
        }

        @Override
        public boolean equals(final @Nullable Object obj) {
            return this == obj || obj instanceof Unresolved other && qname.equals(other.qname);
        }

        @Override
        public String toString() {
            return qname.toString();
        }
    }

    private static final long serialVersionUID = 1L;

    public static Unresolved of(final UnresolvedQName qname) {
        return new Unresolved(qname);
    }

    public static Resolved of(final QName qname) {
        return new Resolved(qname);
    }
}