class-grf-frontend.php

<?php
/**
 * Responsible for rendering the feed output on the front-end.
 *
 * @since 0.1
 */
class GRF_Frontend {

	/**
	 * Feed object.
	 *
	 * @since 0.1
	 * @var object
	 */
	static private $feed;

	/**
	 * The data of the attributes used on the back-end.
	 *
	 * @since 0.1
	 * @var array
	 */
	static private $data;

	/**
	 * Default number of posts.
	 *
	 * @since 0.1
	 * @var integer
	 */
	static private $number_of_posts = 10;

	/**
	 * Render the RSS feed on the front-end.
	 *
	 * @since 0.1
	 * @param array $data
	 * @return mixed
	 */
	static function render( $data ) {
		if( is_admin() ) {
			return;
		}

		self::$data = $data;

		if( ! empty( self::$data[ 'url' ] ) ) {
			self::$feed = GRF_Helper::fetch_feed( self::$data[ 'url' ] );
		}

		$error = self::validate();

		if( ! empty( $error ) ) {
			return $error;
		}

		return self::output();
	}

	/**
	 * Validate the feed and prepare error messages if any.
	 *
	 * @return string
	 */
	static function validate() {
		if( empty( self::$data[ 'url' ] ) ) {
			return __( 'Please set the URL of the RSS feed through the WordPress dashboard.' );
		}

		if( is_wp_error( self::$feed ) || isset( self::$feed->errors ) ) {
			return __( 'Please make sure the provided URL is a valid feed.' );
		}

		if( isset( self::$feed->get_item_quantity ) && ! self::$feed->get_item_quantity() ) {
			return __( 'No feed items found.' );
		}

		return false;
	}

	/**
	 * Prepare the html markup of the feed.
	 *
	 * @return string
	 */
	static function output() {
		if( ! empty( self::$data[ 'numberOfPosts' ] ) ) {
			self::$number_of_posts = intval( self::$data[ 'numberOfPosts' ] );
		}

		$feed_items = self::$feed->get_items( 0, self::$number_of_posts );

		$date_format = get_option( 'date_format' ) . ' | ' . get_option( 'time_format' );

		do_action( 'grf_before_items' );

		ob_start();
		?>
		<div class="grf_items">

			<?php foreach($feed_items as $item) : ?>
				<?php do_action( 'grf_before_item' ); ?>

	            <div class="grf_item">

	                <h3 class="grf_item_title">
	                	<a class="grf_item_link" target="_blank" href="<?php echo esc_url( $item->get_permalink() ); ?>">
	                    	<?php echo esc_html( $item->get_title() ); ?>
	                	</a>
	                </h3>

	                <?php if( isset( self::$data[ 'showDate' ] ) && self::$data[ 'showDate' ] ) : ?>
						<p class="grf_item_date"><?php echo $item->get_date( $date_format ); ?></p>
	            	<?php endif; ?>

					<?php if( isset( self::$data[ 'showDescription' ] ) && self::$data[ 'showDescription' ] && method_exists( $item, 'get_description' ) && $item->get_description() ) : ?>

						<p class="grf_item_description">
							<?php echo $item->get_description(); ?>
						</p>

					<?php endif; ?>


					<?php if( isset( self::$data[ 'showContent'] ) && self::$data[ 'showContent' ] && method_exists( $item, 'get_content' ) && $item->get_content() ) : ?>

						<p class="grf_item_description">
							<?php echo $item->get_content(); ?>
						</p>

					<?php endif; ?>

					<?php do_action( 'grf_after_item' ); ?>

	            </div>

			<?php endforeach; ?>

		</div>
		<?php
		$output = ob_get_clean();

		do_action('grf_after_items');

		return apply_filters('grf_frontend_output', $output);
	}
}