[wp-kama embed] Interlinking posts in WordPress (previous posts from category). Function 2 -- https://wp-kama.com/2186

kama_previous_posts_from_tax_lis.php

/**
 * Предыдущие записи из рубрики (относительно текущей записи) +
 * кольцевая перелинковка (можно указывать таксономию и тип записи).
 *
 * Кэширует результат в объектный кэш, если он включен.
 *
 * Вызываем функцию так:
 *
 *     echo kama_previous_posts_from_tax_lis( [
 *         'post_num' => 5,
 *         'format' => '{date:j.M.Y} - {a}{title}{/a}',
 *     ] );
 *
 * @param array|string $args {
 *     Parameters passed as array or query string.
 *
 *     @type int          $post_num      Количество ссылок.
 *     @type string       $format        {thumb} {date:j.M.Y} - {a}{title}{/a} ({comments})
 *     @type string       $list_tag      Тег-обертка каждой ссылки.
 *     @type string       $tax           Таксономия. Пр. category.
 *     @type string|array $exclude_terms Элементы таксономии посты из которых нужно исключить (через запятую или в массиве).
 *                                       Указываем term_id или term_slug.
 *     @type string       $post_type     Тип записи. пр. post.
 * }
 *
 * @version 1.3
 */
function kama_previous_posts_from_tax_lis( $args = array() ){
	global $post, $wpdb;

	$rg = (object) wp_parse_args( $args, [
		'post_num'      => 5,
		'format'        => '',
		'list_tag'      => 'li',
		'tax'           => 'category',
		'post_type'     => 'post',
		'exclude_terms' => '',
	] );

	if( wp_using_ext_object_cache() ){
		$cache_key = md5( __FUNCTION__ . $post->ID );
		$cache_flag = __FUNCTION__;

		if( $cache_out = wp_cache_get( $cache_key, $cache_flag ) ){
			return $cache_out;
		}
	}

	// wp_parse_list() analog to work with WP < 5.1
	if ( is_string( $rg->exclude_terms ) ) {
		$rg->exclude_terms = preg_split( '/[\s,]+/', $rg->exclude_terms, -1, PREG_SPLIT_NO_EMPTY );
	}
	if( 'exclude_terms' ){
		$exclude_terms = $rg->exclude_terms;
		foreach( $exclude_terms as & $term_id ){
			if( ! is_numeric( $term_id ) ){
				$term = get_term_by( 'slug', $term_id, $rg->tax );
				$term_id = $term ? $term->term_id : 0;
			}
			else {
				$term_id = (int) $term_id;
			}
		}
		unset( $term_id );
		$exclude_terms = array_map( 'intval', array_filter( $exclude_terms ) );

		$AND_NOT_IN = $exclude_terms ? sprintf( ' AND term_id NOT IN (%s)', implode( ',', $exclude_terms ) ) : '';
	}

	$sub_query_term_id = $wpdb->prepare(
		"(SELECT term_id FROM $wpdb->term_relationships rl
			LEFT JOIN $wpdb->term_taxonomy tx ON (rl.term_taxonomy_id = tx.term_taxonomy_id)
			WHERE object_id = %d AND tx.taxonomy = %s $AND_NOT_IN
			LIMIT 1)",
		$post->ID, $rg->tax
	);

	$WHERE_arr = [
		"p.post_status = 'publish'",
		"tax.term_id = $sub_query_term_id",
		$wpdb->prepare( 'p.post_date < %s', $post->post_date ),
		$wpdb->prepare( 'tax.taxonomy = %s', $rg->tax ),
		$wpdb->prepare( 'p.post_type = %s', $rg->post_type ),
	];

	$SELECT = "SELECT ID, post_title, post_date, comment_count, guid
		FROM $wpdb->posts p
		LEFT JOIN $wpdb->term_relationships rel ON (p.ID = rel.object_id)
		LEFT JOIN $wpdb->term_taxonomy tax ON (rel.term_taxonomy_id = tax.term_taxonomy_id)";

	$WHERE = implode( ' AND ', $WHERE_arr );
	$ORDER_BY = 'ORDER BY p.post_date DESC';

	$sql = "$SELECT WHERE $WHERE $ORDER_BY LIMIT " . (int) $rg->post_num;

	$posts_data = $wpdb->get_results( $sql );

	$posts_count = count( $posts_data );

	// если количество меньше нужного, делаем 2-й запрос (кольцевая перелинковка)
	if( ! $posts_data || $posts_count < $rg->post_num ){
		$NOT_IN = $post->ID;
		foreach( $posts_data as $pdata ){
			$NOT_IN .= ",$pdata->ID";
		}

		$WHERE_arr[] = "p.ID NOT IN ($NOT_IN)";
		$WHERE = implode( ' AND ', $WHERE_arr );

		$sql = "$SELECT WHERE $WHERE $ORDER_BY LIMIT " . (int) ( $rg->post_num - $posts_count );

		$res2 = $wpdb->get_results( $sql );

		$posts_data = array_merge( $posts_data, $res2 );
	}

	if( ! $posts_data ){
		return '';
	}

	// вывод
	$date_match = false;
	if( $rg->format ){
		preg_match( '!{date:(.*?)}!', $rg->format, $date_match );
	}

	$add_thumb = false !== strpos( $rg->format, '{thumb}' );

	$out = '';
	foreach( $posts_data as $pdata ){
		$x = ( ( $x ?? '' ) === 'li1' ) ? 'li2' : 'li1';

		$a = sprintf( '<a href="%s" title="%s">', get_permalink( $pdata->ID ), esc_attr( $pdata->post_title ) );

		if( $rg->format ){
			$formated = strtr( $rg->format, [
				'{title}'    => esc_html( $pdata->post_title ),
				'{a}'        => $a,
				'{/a}'       => '</a>',
				'{comments}' => $pdata->comment_count ?: '',
			] );

			if( $add_thumb ){
				$formated = str_replace( '{thumb}', get_the_post_thumbnail( $pdata->ID, 'thumbnail' ), $formated );
			}

			// есть дата
			if( $date_match ){
				$formated = str_replace( $date_match[0], apply_filters( 'the_time', mysql2date( $date_match[1], $pdata->post_date ) ), $formated );
			}
		}
		else{
			$formated = $a . esc_html( $pdata->post_title ) . '</a>';
		}

		$out .= "\t<li class=\"$x\">$formated</li>\n";
	}

	if( wp_using_ext_object_cache() ){
		wp_cache_add( $cache_key, $out, $cache_flag );
	}

	return $out;
}