WordPress/wp-includes/widgets/class-wp-widget-archives.php

<?php
/**
 * Widget API: WP_Widget_Archives class
 *
 * @package WordPress
 * @subpackage Widgets
 * @since 4.4.0
 */

/**
 * Core class used to implement the Archives widget.
 *
 * @since 2.8.0
 *
 * @see WP_Widget
 */
class WP_Widget_Archives extends WP_Widget {

	/**
	 * Sets up a new Archives widget instance.
	 *
	 * @since 2.8.0
	 */
	public function __construct() {
		$widget_ops = array(
			'classname'                   => 'widget_archive',
			'description'                 => __( 'A monthly archive of your site&#8217;s Posts.' ),
			'customize_selective_refresh' => true,
		);
		parent::__construct( 'archives', __( 'Archives' ), $widget_ops );
	}

	/**
	 * Outputs the content for the current Archives widget instance.
	 *
	 * @since 2.8.0
	 *
	 * @param array $args     Display arguments including 'before_title', 'after_title',
	 *                        'before_widget', and 'after_widget'.
	 * @param array $instance Settings for the current Archives widget instance.
	 */
	public function widget( $args, $instance ) {
		$title = ! empty( $instance['title'] ) ? $instance['title'] : __( 'Archives' );

		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );

		$c = ! empty( $instance['count'] ) ? '1' : '0';
		$d = ! empty( $instance['dropdown'] ) ? '1' : '0';

		echo $args['before_widget'];

		if ( $title ) {
			echo $args['before_title'] . $title . $args['after_title'];
		}

		if ( $d ) {
			$dropdown_id = "{$this->id_base}-dropdown-{$this->number}";
			?>
		<label class="screen-reader-text" for="<?php echo esc_attr( $dropdown_id ); ?>"><?php echo $title; ?></label>
		<select id="<?php echo esc_attr( $dropdown_id ); ?>" name="archive-dropdown">
			<?php
			/**
			 * Filters the arguments for the Archives widget drop-down.
			 *
			 * @since 2.8.0
			 * @since 4.9.0 Added the `$instance` parameter.
			 *
			 * @see wp_get_archives()
			 *
			 * @param array $args     An array of Archives widget drop-down arguments.
			 * @param array $instance Settings for the current Archives widget instance.
			 */
			$dropdown_args = apply_filters(
				'widget_archives_dropdown_args',
				array(
					'type'            => 'monthly',
					'format'          => 'option',
					'show_post_count' => $c,
				),
				$instance
			);

			switch ( $dropdown_args['type'] ) {
				case 'yearly':
					$label = __( 'Select Year' );
					break;
				case 'monthly':
					$label = __( 'Select Month' );
					break;
				case 'daily':
					$label = __( 'Select Day' );
					break;
				case 'weekly':
					$label = __( 'Select Week' );
					break;
				default:
					$label = __( 'Select Post' );
					break;
			}

			$type_attr = current_theme_supports( 'html5', 'script' ) ? '' : ' type="text/javascript"';
			?>

			<option value=""><?php echo esc_attr( $label ); ?></option>
			<?php wp_get_archives( $dropdown_args ); ?>

		</select>

<script<?php echo $type_attr; ?>>
/* <![CDATA[ */
(function() {
	var dropdown = document.getElementById( "<?php echo esc_js( $dropdown_id ); ?>" );
	function onSelectChange() {
		if ( dropdown.options[ dropdown.selectedIndex ].value !== '' ) {
			document.location.href = this.options[ this.selectedIndex ].value;
		}
	}
	dropdown.onchange = onSelectChange;
})();
/* ]]> */
</script>

		<?php } else { ?>
		<ul>
			<?php
			wp_get_archives(
				/**
				 * Filters the arguments for the Archives widget.
				 *
				 * @since 2.8.0
				 * @since 4.9.0 Added the `$instance` parameter.
				 *
				 * @see wp_get_archives()
				 *
				 * @param array $args     An array of Archives option arguments.
				 * @param array $instance Array of settings for the current widget.
				 */
				apply_filters(
					'widget_archives_args',
					array(
						'type'            => 'monthly',
						'show_post_count' => $c,
					),
					$instance
				)
			);
			?>
		</ul>
			<?php
		}

		echo $args['after_widget'];
	}

	/**
	 * Handles updating settings for the current Archives widget instance.
	 *
	 * @since 2.8.0
	 *
	 * @param array $new_instance New settings for this instance as input by the user via
	 *                            WP_Widget_Archives::form().
	 * @param array $old_instance Old settings for this instance.
	 * @return array Updated settings to save.
	 */
	public function update( $new_instance, $old_instance ) {
		$instance             = $old_instance;
		$new_instance         = wp_parse_args(
			(array) $new_instance,
			array(
				'title'    => '',
				'count'    => 0,
				'dropdown' => '',
			)
		);
		$instance['title']    = sanitize_text_field( $new_instance['title'] );
		$instance['count']    = $new_instance['count'] ? 1 : 0;
		$instance['dropdown'] = $new_instance['dropdown'] ? 1 : 0;

		return $instance;
	}

	/**
	 * Outputs the settings form for the Archives widget.
	 *
	 * @since 2.8.0
	 *
	 * @param array $instance Current settings.
	 */
	public function form( $instance ) {
		$instance = wp_parse_args(
			(array) $instance,
			array(
				'title'    => '',
				'count'    => 0,
				'dropdown' => '',
			)
		);
		?>
		<p><label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e( 'Title:' ); ?></label> <input class="widefat" id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" type="text" value="<?php echo esc_attr( $instance['title'] ); ?>" /></p>
		<p>
			<input class="checkbox" type="checkbox"<?php checked( $instance['dropdown'] ); ?> id="<?php echo $this->get_field_id( 'dropdown' ); ?>" name="<?php echo $this->get_field_name( 'dropdown' ); ?>" /> <label for="<?php echo $this->get_field_id( 'dropdown' ); ?>"><?php _e( 'Display as dropdown' ); ?></label>
			<br/>
			<input class="checkbox" type="checkbox"<?php checked( $instance['count'] ); ?> id="<?php echo $this->get_field_id( 'count' ); ?>" name="<?php echo $this->get_field_name( 'count' ); ?>" /> <label for="<?php echo $this->get_field_id( 'count' ); ?>"><?php _e( 'Show post counts' ); ?></label>
		</p>
		<?php
	}
}