url specific cache key & add (small) cache for failed requests

classes/class-lessons.php

@@ -42,37 +42,45 @@ public function get_items() {
 	 * @return array
 	 */
 	public function get_remote_api_items() {
-		$cached = \progress_planner()->get_cache()->get( 'lessons' );
-		if ( is_array( $cached ) && ! empty( $cached ) ) {
+
+		/**
+		 * Filter the endpoint url for the lessons.
+		 *
+		 * @param string $endpoint The endpoint url.
+		 */
+		$url = apply_filters(
+			'progress_planner_lessons_endpoint',
+			'https://progressplanner.com/wp-json/progress-planner-saas/v1/free-lessons'
+		);
+
+		$cache_key = 'lessons-' . $url;
+
+		$cached = \progress_planner()->get_cache()->get( $cache_key );
+		if ( is_array( $cached ) ) {
 			return $cached;
 		}
 
 		$response = \wp_remote_get(
-			/**
-			 * Filter the endpoint url for the lessons.
-			 *
-			 * @param string $endpoint The endpoint url.
-			 */
-			apply_filters(
-				'progress_planner_lessons_endpoint',
-				'https://progressplanner.com/wp-json/progress-planner-saas/v1/free-lessons'
-			)
+			$url
 		);
 
 		if ( \is_wp_error( $response ) ) {
+			\progress_planner()->get_cache()->set( $cache_key, [], 5 * MINUTE_IN_SECONDS );
 			return [];
 		}
 
 		if ( 200 !== (int) wp_remote_retrieve_response_code( $response ) ) {
+			\progress_planner()->get_cache()->set( $cache_key, [], 5 * MINUTE_IN_SECONDS );
 			return [];
 		}
 
 		$json = json_decode( \wp_remote_retrieve_body( $response ), true );
 		if ( ! is_array( $json ) ) {
+			\progress_planner()->get_cache()->set( $cache_key, [], 5 * MINUTE_IN_SECONDS );
 			return [];
 		}
 
-		\progress_planner()->get_cache()->set( 'lessons', $json, WEEK_IN_SECONDS );
+		\progress_planner()->get_cache()->set( $cache_key, $json, WEEK_IN_SECONDS );
 
 		return $json;
 	}