add_filter(
	'graphql_process_http_request_response',
	function ( mixed $response, mixed $result, mixed $operation, mixed $request ): mixed {
		if ( class_exists( \WPGraphQL\Utils\QueryAnalyzer::class ) && 
			method_exists( \WPGraphQL\Utils\QueryAnalyzer::class, 'areNodesResolved' ) && 
			method_exists( \WPGraphQL\Utils\QueryAnalyzer::class, 'resetNodesResolved' ) ) {

			$nodes_resolved = \WPGraphQL\Utils\QueryAnalyzer::areNodesResolved();

			if ( ! $nodes_resolved ) {
				header( 'Cache-Control: no-cache, must-revalidate' );
			}

			// Correctly reset nodes_resolved for the next request.
			\WPGraphQL\Utils\QueryAnalyzer::resetNodesResolved();
		} 

		return $response;
	},
	10,
	4
);

add_filter(
	'graphql_process_http_request_response',
	function ( mixed $response, mixed $result, mixed $operation, mixed $request ): mixed {
		if (  ! empty( $response['X-GraphQL-Keys'] ) { // 👈 (we can also conditionally check and invalidate based a specific key.
			header( 'Cache-Control: no-cache, must-revalidate' );

			// We no longer need to reset between requests, since we're not dealing with static state.
		} 

		return $response;
	},
	10,
	4
);

add_filter(
	'graphql_process_http_request_response',
	function ( mixed $response, mixed $result, mixed $operation, mixed $request, mixed $router ): mixed { // 👈 Alternatively, the Request class.
		if ( $router instanceof \WPGraphQL\Router && $router->get_request() instanceof \WPGraphQL\Request) {
			
			$nodes_resolved = $router->get_request()->get_query_analyzer()->is_nodes_resolved() // 👈 Since this is an instance method, we dont need to worry about the global state.

			if ( ! $nodes_resolved ) {
				header( 'Cache-Control: no-cache, must-revalidate' );
			}

			// Nothing to reset 🚀
		} 

		return $response;
	},
	10,
	4
);

/**
 * Recursively checks if any of the items in the given array are non-empty.
 * Returns true if at least one item is a non-empty value or a non-empty array.
 * Returns false if all items are empty or are empty arrays.
 *
 * @param mixed $items The item or array to check for non-empty items.
 * @return bool True if at least one item is non-empty or contains a non-empty array, otherwise false.
 */
function contains_non_empty_item( mixed $items ): bool {
	if ( is_array( $items ) ) {
		foreach ( $items as $item ) {
			if ( contains_non_empty_item( $item ) ) {
				return true; // Found a non-empty item or non-empty array.
			}
		}
		return false; // All items are empty or are empty arrays.
	} else {
		return ! empty( $items ); // Non-array item, return if it's non-empty.
	}
}

/**
 * Modifies the HTTP response of a GraphQL request.
 *
 * Hooks into the 'graphql_process_http_request_response' filter.
 * Checks if the GraphQL response data contains any non-empty item.
 * If not, it sets the 'Cache-Control' header to 'no-cache, must-revalidate'.
 *
 * @param GraphQL\Executor\ExecutionResult $response The initial response object.
 * @return mixed The modified response object.
 */
function modify_graphql_response( GraphQL\Executor\ExecutionResult $response ): mixed {
	if ( ! contains_non_empty_item( $response->data ) ) {
		header( 'Cache-Control: no-cache, must-revalidate' );
	}

	return $response;
}

add_filter( 'graphql_process_http_request_response', 'modify_graphql_response', 10, 4 );

/**
* Return headers
*
* @param array<string,mixed> $headers The array of headers being returned
*
* @return array<string,mixed>
*/
public function get_headers( array $headers = [] ): array {
  $keys = $this->get_graphql_keys();
  
  if ( ! empty( $keys ) ) {
	  $headers['X-GraphQL-Query-ID'] = $this->query_id ?: null;
	  $headers['X-GraphQL-Keys']     = $keys['keys'] ?: null;
  }
  
  /**
  * @param array<string,mixed> $headers The array of headers being returned
  * @param \WPGraphQL\Utils\QueryAnalyzer $query_analyzer The instance of the query analyzer
  */
  return apply_filters( 'graphql_query_analyzer_get_headers', $headers, $this );
}

add_filter( 'graphql_query_analyzer_get_headers', function( $headers, \WPGraphQL\Utils\QueryAnalyzer $query_analyzer ) {
	if ( empty( $query_analyzer->get_runtime_nodes() ) ) {
		$headers['Cache-Control'] = 'no-cache, must-revalidate';
	}
	return $headers;
}, 10, 2 );

add_filter( 'graphql_query_analyzer_get_headers', function( $headers, \WPGraphQL\Utils\QueryAnalyzer $query_analyzer ) {
	if ( empty( $query_analyzer->get_runtime_nodes() ) ) {
		$headers['Cache-Control'] = 'no-cache, must-revalidate';
	}
	return $headers;
}, 20, 2 );

add_filter( 'graphql_response_headers_to_send', function( $headers ) {
	$request = \WPGraphQL\Router::get_request();
	if ( ! $request instanceof \WPGraphQL\Request ) {
		return $headers;
	}
	$query_analyzer = $request->get_query_analyzer();
	if ( empty( $query_analyzer->get_runtime_nodes() ) ) {
		$headers['Cache-Control'] = 'no-cache, must-revalidate';
	}
	return $headers;
}, 20, 1 );