<?php

add_filter( 'rest_prepare_post', 'amp_add_amphtml_link_to_rest_response', 10, 2 );

function amp_add_link_to_rest_response( $response, $post ) {
	if ( ! post_supports_amp( $post ) ) {
		return $response;
	}

	$response->add_link( 'amphtml', amp_get_permalink( $post->ID ) );

	return $response;
}