[SmartCrawl] - Autolinks for AMP. Since the AMP plugin isn't using the_content filter we're overriding the `AMPforWP\\AMPVendor\\amp_render` method

smartcrawl-amp-autolinks.php

<?php
/**
* Plugin Name: [SmartCrawl] - Autolinks for AMP
* Plugin URI: https://premium.wpmudev.org/
* Description: Since the AMP plugin isn't using the_content filter we're overriding the `AMPforWP\\AMPVendor\\amp_render` method
* Author: Panos Lyrakis @ WPMUDEV
* Author URI: https://premium.wpmudev.org/
* License: GPLv2 or later
*/

namespace AMPforWP\AMPVendor;

if ( ! function_exists('AMPforWP\\AMPVendor\\amp_render') ) {
	function amp_render() {

		global $ampforwpTemplate;
		$sc_autolinks = \Smartcrawl_Autolinks::get();

		amp_load_classes();

		$post_id = get_queried_object_id();
		do_action( 'pre_amp_render_post', $post_id );

		amp_add_post_template_actions();
		$template = $ampforwpTemplate = new AMP_Post_Template( $post_id );
		ob_start();
		$template->load();

		$content = $sc_autolinks->the_content_filter( ob_get_clean() );
		echo $content;
		// Set Header: last modified information
		if( is_singular() && $post_id ) {
            header("Last-Modified: " . get_the_modified_time("D, d M Y H:i:s", $post_id) );
	    }
		exit;
	}
}