Wordpress endpoint aggregator with Cache

class-aggregator.php

<?php

/**
 * Requires PHP 5.6+ due to the use of the splat operator and the [] "array declaration".
 */

class Rest_Aggregator {

	/**
	 * Page number to fetch.
	 *
	 * @var integer
	 */
	private $page = 1;

	/**
	 * Array of generated posts.
	 *
	 * @var array
	 */
	private $posts = [];

	/**
	 * List of endpoints to fetch from.
	 *
	 * @var array
	 */
	private $endpoints = [];

	/**
	 * Disable cache.
	 *
	 * @var boolean
	 */
	public $disable_cache = false;

	/**
	 * Constructor.
	 *
	 * @param array $endpoints array of endpoint url.
	 */
	public function __construct( array $endpoints ) {
		$this->endpoints = $endpoints;
	}

	/**
	 * Get the posts wether it was cached or not.
	 *
	 * @see get_cache()
	 * @see merge()
	 *
	 * @param integer $page the page to show.
	 * @return array
	 */
	public function get_posts( int $page = 1 ) {
		$this->page = $page;

		if ( ! $this->disable_cache ) {
			$this->get_cache();
		}

		if ( isset( $this->posts[ $page ] ) ) {
			return $this->posts[ $page ];
		} else {
			$this->merge();

			if ( ! empty( $this->posts ) ) {
				return $this->posts[ $page ];
			}
		}

		return [];
	}

	/**
	 * Merge posts based off endpoints into 1 single array and
	 * sort it by posted date this also set the cache.
	 *
	 * @see get_remote()
	 * @see sort()
	 * @see set_cache()
	 *
	 * @return void
	 */
	private function merge() {
		$endpoints = $this->endpoints;
		$tmp_posts = [];

		if ( ! empty( $endpoints ) && is_array( $endpoints ) ) {
			foreach ( $endpoints as $endpoint ) {
				$value = $this->get_remote( $endpoint );

				if ( is_array( $value ) ) {
					$tmp_posts[] = $value;
				} elseif ( is_object( $value ) ) {
					$tmp_posts[][] = $value;
				}
			}

			/**
			 * Splat Operator
			 *
			 * @see https://blog.programster.org/php-splat-operator
			 */
			$tmp_posts = array_merge( ...$tmp_posts );

			$this->posts[ $this->page ] = $this->sort( $tmp_posts );
		}

		if ( ! $this->disable_cache ) {
			$this->set_cache();
		}
	}

	/**
	 * Fetch reponse from provided endpoint url.
	 *
	 * @see wp_remote_get()
	 * @see wp_remote_retrieve_response_code()
	 * @see wp_remote_retrieve_body()
	 *
	 * @param string $endpoint The URL of the endpoint.
	 * @return array
	 */
	private function get_remote( $endpoint ) {
		$url = add_query_arg( 'page', $this->page, $endpoint );

		$request  = wp_remote_get( $url );
		$response = wp_remote_retrieve_response_code( $request );

		if ( ! is_wp_error( $request ) && 200 === $response ) {
			return json_decode( wp_remote_retrieve_body( $request ) );
		}

		// TODO: Add error reporting if failed to connect.
		return [];
	}

	/**
	 * Get Cache.
	 *
	 * @see get_transient()
	 * @see get_cache_key()
	 *
	 * @return void
	 */
	private function get_cache() {
		$posts = get_transient( $this->get_cache_key() );

		if ( is_array( $posts ) ) {
			$this->posts[ $this->page ] = $posts;
		}
	}

	/**
	 * Sets cache.
	 *
	 * @see get_field()
	 * @see set_transient()
	 * @see get_cache_key()
	 *
	 * @return void
	 */
	private function set_cache() {
		$exp_option = get_field( 'cache_expiration', 'rest_options' );
		$expiration = ( ! empty( $exp_option ) ) ? (int) $exp_option : 15;

		if ( ! empty( $this->posts ) ) {
			set_transient( $this->get_cache_key(), $this->posts[ $this->page ], $expiration * MINUTE_IN_SECONDS );
		}
	}

	/**
	 * Clear cache.
	 *
	 * @see delete_transient()
	 * @see get_cache_key()
	 *
	 * @return void
	 */
	public function clear_cache() {
		delete_transient( $this->get_cache_key() );
	}

	/**
	 * Get unique hashed key based on the array of endpoints.
	 *
	 * @return string Hashed key
	 */
	private function get_cache_key() {
		$prefix = $this->page . '_';
		$infix  = implode( '_', $this->endpoints );
		$infix  = str_replace( array( 'http://', 'https://' ), '', $infix );
		$suffix = '_endpoint_transient';

		return md5( $prefix . $infix . $suffix );
	}

	/**
	 * Sorts final array by date.
	 *
	 * @param array $posts array of posts to sort.
	 * @return array $posts array of posts sorted.
	 */
	private function sort( array $posts ) {
		usort( $posts, function ( $a, $b ) {
			return strtotime( $a->date ) - strtotime( $b->date );
		} );

		$posts = array_reverse( $posts );

		return $posts;
	}

}

example.php

<?php
 require_once 'class-aggregator.php';
 
 $endpoints = new CU_Rest_Aggregator([
    'https://website.com/wp-json/wp/v2/posts',
    'https://website.com/wp-json/wp/v2/posts',
 ]);

$posts = $endpoints->get_posts();

/**
 * Available public functions to use.
 */
$endpoints->disable_cache = true;
$endpoints->clear_cache = true;

foreach ( $posts as $post ) {
   echo esc_url( $post->link );
}