wp_get_archives() WordPress Function

function wp_get_archives( $args = '' ) {
	global $wpdb, $wp_locale;

	$defaults = array(
		'type'            => 'monthly',
		'limit'           => '',
		'format'          => 'html',
		'before'          => '',
		'after'           => '',
		'show_post_count' => false,
		'echo'            => 1,
		'order'           => 'DESC',
		'post_type'       => 'post',
		'year'            => get_query_var( 'year' ),
		'monthnum'        => get_query_var( 'monthnum' ),
		'day'             => get_query_var( 'day' ),
		'w'               => get_query_var( 'w' ),
	);

	$parsed_args = wp_parse_args( $args, $defaults );

	$post_type_object = get_post_type_object( $parsed_args['post_type'] );
	if ( ! is_post_type_viewable( $post_type_object ) ) {
		return;
	}

	$parsed_args['post_type'] = $post_type_object->name;

	if ( '' === $parsed_args['type'] ) {
		$parsed_args['type'] = 'monthly';
	}

	if ( ! empty( $parsed_args['limit'] ) ) {
		$parsed_args['limit'] = absint( $parsed_args['limit'] );
		$parsed_args['limit'] = ' LIMIT ' . $parsed_args['limit'];
	}

	$order = strtoupper( $parsed_args['order'] );
	if ( 'ASC' !== $order ) {
		$order = 'DESC';
	}

	// This is what will separate dates on weekly archive links.
	$archive_week_separator = '–';

	$sql_where = $wpdb->prepare( "WHERE post_type = %s AND post_status = 'publish'", $parsed_args['post_type'] );

	/**
	 * Filters the SQL WHERE clause for retrieving archives.
	 *
	 * @since 2.2.0
	 *
	 * @param string $sql_where   Portion of SQL query containing the WHERE clause.
	 * @param array  $parsed_args An array of default arguments.
	 */
	$where = apply_filters( 'getarchives_where', $sql_where, $parsed_args );

	/**
	 * Filters the SQL JOIN clause for retrieving archives.
	 *
	 * @since 2.2.0
	 *
	 * @param string $sql_join    Portion of SQL query containing JOIN clause.
	 * @param array  $parsed_args An array of default arguments.
	 */
	$join = apply_filters( 'getarchives_join', '', $parsed_args );

	$output = '';

	$last_changed = wp_cache_get_last_changed( 'posts' );

	$limit = $parsed_args['limit'];

	if ( 'monthly' === $parsed_args['type'] ) {
		$query   = "SELECT YEAR(post_date) AS `year`, MONTH(post_date) AS `month`, count(ID) as posts FROM $wpdb->posts $join $where GROUP BY YEAR(post_date), MONTH(post_date) ORDER BY post_date $order $limit";
		$key     = md5( $query );
		$key     = "wp_get_archives:$key:$last_changed";
		$results = wp_cache_get( $key, 'posts' );
		if ( ! $results ) {
			$results = $wpdb->get_results( $query );
			wp_cache_set( $key, $results, 'posts' );
		}
		if ( $results ) {
			$after = $parsed_args['after'];
			foreach ( (array) $results as $result ) {
				$url = get_month_link( $result->year, $result->month );
				if ( 'post' !== $parsed_args['post_type'] ) {
					$url = add_query_arg( 'post_type', $parsed_args['post_type'], $url );
				}
				/* translators: 1: Month name, 2: 4-digit year. */
				$text = sprintf( __( '%1$s %2$d' ), $wp_locale->get_month( $result->month ), $result->year );
				if ( $parsed_args['show_post_count'] ) {
					$parsed_args['after'] = ' (' . $result->posts . ')' . $after;
				}
				$selected = is_archive() && (string) $parsed_args['year'] === $result->year && (string) $parsed_args['monthnum'] === $result->month;
				$output  .= get_archives_link( $url, $text, $parsed_args['format'], $parsed_args['before'], $parsed_args['after'], $selected );
			}
		}
	} elseif ( 'yearly' === $parsed_args['type'] ) {
		$query   = "SELECT YEAR(post_date) AS `year`, count(ID) as posts FROM $wpdb->posts $join $where GROUP BY YEAR(post_date) ORDER BY post_date $order $limit";
		$key     = md5( $query );
		$key     = "wp_get_archives:$key:$last_changed";
		$results = wp_cache_get( $key, 'posts' );
		if ( ! $results ) {
			$results = $wpdb->get_results( $query );
			wp_cache_set( $key, $results, 'posts' );
		}
		if ( $results ) {
			$after = $parsed_args['after'];
			foreach ( (array) $results as $result ) {
				$url = get_year_link( $result->year );
				if ( 'post' !== $parsed_args['post_type'] ) {
					$url = add_query_arg( 'post_type', $parsed_args['post_type'], $url );
				}
				$text = sprintf( '%d', $result->year );
				if ( $parsed_args['show_post_count'] ) {
					$parsed_args['after'] = ' (' . $result->posts . ')' . $after;
				}
				$selected = is_archive() && (string) $parsed_args['year'] === $result->year;
				$output  .= get_archives_link( $url, $text, $parsed_args['format'], $parsed_args['before'], $parsed_args['after'], $selected );
			}
		}
	} elseif ( 'daily' === $parsed_args['type'] ) {
		$query   = "SELECT YEAR(post_date) AS `year`, MONTH(post_date) AS `month`, DAYOFMONTH(post_date) AS `dayofmonth`, count(ID) as posts FROM $wpdb->posts $join $where GROUP BY YEAR(post_date), MONTH(post_date), DAYOFMONTH(post_date) ORDER BY post_date $order $limit";
		$key     = md5( $query );
		$key     = "wp_get_archives:$key:$last_changed";
		$results = wp_cache_get( $key, 'posts' );
		if ( ! $results ) {
			$results = $wpdb->get_results( $query );
			wp_cache_set( $key, $results, 'posts' );
		}
		if ( $results ) {
			$after = $parsed_args['after'];
			foreach ( (array) $results as $result ) {
				$url = get_day_link( $result->year, $result->month, $result->dayofmonth );
				if ( 'post' !== $parsed_args['post_type'] ) {
					$url = add_query_arg( 'post_type', $parsed_args['post_type'], $url );
				}
				$date = sprintf( '%1$d-%2$02d-%3$02d 00:00:00', $result->year, $result->month, $result->dayofmonth );
				$text = mysql2date( get_option( 'date_format' ), $date );
				if ( $parsed_args['show_post_count'] ) {
					$parsed_args['after'] = ' (' . $result->posts . ')' . $after;
				}
				$selected = is_archive() && (string) $parsed_args['year'] === $result->year && (string) $parsed_args['monthnum'] === $result->month && (string) $parsed_args['day'] === $result->dayofmonth;
				$output  .= get_archives_link( $url, $text, $parsed_args['format'], $parsed_args['before'], $parsed_args['after'], $selected );
			}
		}
	} elseif ( 'weekly' === $parsed_args['type'] ) {
		$week    = _wp_mysql_week( '`post_date`' );
		$query   = "SELECT DISTINCT $week AS `week`, YEAR( `post_date` ) AS `yr`, DATE_FORMAT( `post_date`, '%Y-%m-%d' ) AS `yyyymmdd`, count( `ID` ) AS `posts` FROM `$wpdb->posts` $join $where GROUP BY $week, YEAR( `post_date` ) ORDER BY `post_date` $order $limit";
		$key     = md5( $query );
		$key     = "wp_get_archives:$key:$last_changed";
		$results = wp_cache_get( $key, 'posts' );
		if ( ! $results ) {
			$results = $wpdb->get_results( $query );
			wp_cache_set( $key, $results, 'posts' );
		}
		$arc_w_last = '';
		if ( $results ) {
			$after = $parsed_args['after'];
			foreach ( (array) $results as $result ) {
				if ( $result->week != $arc_w_last ) {
					$arc_year       = $result->yr;
					$arc_w_last     = $result->week;
					$arc_week       = get_weekstartend( $result->yyyymmdd, get_option( 'start_of_week' ) );
					$arc_week_start = date_i18n( get_option( 'date_format' ), $arc_week['start'] );
					$arc_week_end   = date_i18n( get_option( 'date_format' ), $arc_week['end'] );
					$url            = add_query_arg(
						array(
							'm' => $arc_year,
							'w' => $result->week,
						),
						home_url( '/' )
					);
					if ( 'post' !== $parsed_args['post_type'] ) {
						$url = add_query_arg( 'post_type', $parsed_args['post_type'], $url );
					}
					$text = $arc_week_start . $archive_week_separator . $arc_week_end;
					if ( $parsed_args['show_post_count'] ) {
						$parsed_args['after'] = ' (' . $result->posts . ')' . $after;
					}
					$selected = is_archive() && (string) $parsed_args['year'] === $result->yr && (string) $parsed_args['w'] === $result->week;
					$output  .= get_archives_link( $url, $text, $parsed_args['format'], $parsed_args['before'], $parsed_args['after'], $selected );
				}
			}
		}
	} elseif ( ( 'postbypost' === $parsed_args['type'] ) || ( 'alpha' === $parsed_args['type'] ) ) {
		$orderby = ( 'alpha' === $parsed_args['type'] ) ? 'post_title ASC ' : 'post_date DESC, ID DESC ';
		$query   = "SELECT * FROM $wpdb->posts $join $where ORDER BY $orderby $limit";
		$key     = md5( $query );
		$key     = "wp_get_archives:$key:$last_changed";
		$results = wp_cache_get( $key, 'posts' );
		if ( ! $results ) {
			$results = $wpdb->get_results( $query );
			wp_cache_set( $key, $results, 'posts' );
		}
		if ( $results ) {
			foreach ( (array) $results as $result ) {
				if ( '0000-00-00 00:00:00' !== $result->post_date ) {
					$url = get_permalink( $result );
					if ( $result->post_title ) {
						/** This filter is documented in wp-includes/post-template.php */
						$text = strip_tags( apply_filters( 'the_title', $result->post_title, $result->ID ) );
					} else {
						$text = $result->ID;
					}
					$selected = get_the_ID() === $result->ID;
					$output  .= get_archives_link( $url, $text, $parsed_args['format'], $parsed_args['before'], $parsed_args['after'], $selected );
				}
			}
		}
	}

	if ( $parsed_args['echo'] ) {
		echo $output;
	} else {
		return $output;
	}
}