change permalink podcast post permalink structure with podcast series term

/**
 * Filter the default permalink structure before WordPress replaces permalink tags.
 *
 * This hook is used to switch the permalink structure only for standard posts
 * that have at least one term assigned in the `jnews-series` taxonomy.
 *
 * Example:
 * Default structure  : /%category%/%postname%/
 * Custom structure   : /podcast/%jnwes-series%/%postname%/
 */
add_filter(
    'pre_post_link',
    function ( $permalink, $post, $leavename ) {
        if ( 'post' !== $post->post_type ) {
            return $permalink;
        }

        $series = wp_get_post_terms( $post->ID, 'jnews-series' );
        $series = is_wp_error( $series ) ? '' : $series;
        $series = is_array( $series ) ? ( ! empty( $series ) ? $series[0] : $series ) : $series;

        if ( ! empty( $series ) && ! is_wp_error( $series ) ) {
            return '/podcast/%jnwes-series%/%postname%/';
        }

        return $permalink;
    },
    10,
    3
);

/**
 * Replace the custom permalink tag with the actual taxonomy term slug.
 *
 * After `pre_post_link` changes the permalink structure, this hook replaces
 * `%jnwes-series%` with the real slug from the assigned `jnews-series` term.
 *
 * If no valid term is found, it falls back to `uncategorized`.
 */
add_filter(
    'post_link',
    function ( $permalink, $post, $leavename ) {
        if ( 'post' !== $post->post_type ) {
            return $permalink;
        }

        if ( false === strpos( $permalink, 'podcast/%jnwes-series%' ) ) {
            return $permalink;
        }

        $series = wp_get_post_terms( $post->ID, 'jnews-series' );
        $series = is_wp_error( $series ) ? '' : $series;
        $series = is_array( $series ) ? ( ! empty( $series ) ? $series[0] : $series ) : $series;

        if ( empty( $series ) || is_wp_error( $series ) ) {
            return str_replace( 'podcast/%jnwes-series%', 'uncategorized', $permalink );
        }

        return str_replace( '%jnwes-series%', $series->slug, $permalink );
    },
    10,
    3
);

/**
 * Register custom query variables used by the rewrite rule.
 *
 * `jnews_series_slug` is used to store the series term slug taken from the URL.
 * `jnews_series_post_slug` is registered here for possible future use, even though
 * it is not used in the current rewrite target.
 */
add_filter(
    'query_vars',
    function ( $vars ) {
        $vars[] = 'jnews_series_slug';
        $vars[] = 'jnews_series_post_slug';
        return $vars;
    }
);

/**
 * Add a custom rewrite rule for podcast series single posts.
 *
 * This rule maps URLs like:
 * /podcast/series-slug/post-slug/
 *
 * Into query vars that WordPress can understand:
 * - post_type=post
 * - name=post-slug
 * - jnews_series_slug=series-slug
 *
 * The rule is added at the top so it takes priority over more generic rules.
 */
add_action(
    'init',
    function () {
        add_rewrite_rule(
            '^podcast/([^/]+)/([^/]+)/?$',
            'index.php?post_type=post&name=$matches[2]&jnews_series_slug=$matches[1]',
            'top'
        );
    }
);

/**
 * Modify the main query so WordPress only loads posts that belong to
 * the requested `jnews-series` term from the URL.
 *
 * Without this hook, WordPress may find a post by slug alone, even if the post
 * does not belong to the requested series term.
 *
 * This ensures the URL:
 * /podcast/series-slug/post-slug/
 *
 * Only resolves if `post-slug` is actually assigned to `series-slug`.
 */
add_action(
    'pre_get_posts',
    function ( $query ) {
        if ( is_admin() || ! $query->is_main_query() ) {
            return;
        }

        $series_slug = $query->get( 'jnews_series_slug' );
        $post_slug   = $query->get( 'name' );

        if ( empty( $series_slug ) || empty( $post_slug ) ) {
            return;
        }

        $query->set( 'post_type', 'post' );
        $query->set(
            'tax_query',
            array(
                array(
                    'taxonomy' => 'jnews-series',
                    'field'    => 'slug',
                    'terms'    => $series_slug,
                ),
            )
        );
    }
);

/**
 * Redirect non-canonical series URLs to the correct permalink.
 *
 * This hook runs before the template is loaded and compares the current URL
 * against the canonical permalink generated by WordPress.
 *
 * If the requested URL does not match the correct permalink, a 301 redirect
 * is performed to avoid duplicate URLs and keep the permalink consistent.
 */
add_action(
    'template_redirect',
    function () {
        if ( ! is_single() ) {
            return;
        }

        $post = get_queried_object();

        if ( ! $post instanceof WP_Post || 'post' !== $post->post_type ) {
            return;
        }

        $requested_series = get_query_var( 'jnews_series_slug' );

        if ( empty( $requested_series ) ) {
            return;
        }

        $canonical = get_permalink( $post );
        $current   = home_url( trailingslashit( $GLOBALS['wp']->request ) );

        if ( untrailingslashit( $canonical ) !== untrailingslashit( $current ) ) {
            wp_safe_redirect( $canonical, 301 );
            exit;
        }
    }
);