Add timestamp to end of media assets replaced by Enable Media Replace

media-versioned-cache.php

<?php
/**
 * Automatic Media & Post Cache Purging
 * when using the Enable Media Replace plugin.
 *
 * @package Tyme
 */

namespace Tyme\CacheManager;

/**
 * Hook actions into WP
 *
 * @return void
 */
function setup() {
	$n = function( $func ) {
		return __NAMESPACE__ . "\\$func";
	};

	// Media Cache
	if ( apply_filters( 'tyme_media_cache_manager', true ) ) {
		add_action( 'enable-media-replace-upload-done', $n( 'add_replaced_timestamp' ) );
		add_filter( 'wp_get_attachment_url', $n( 'add_cache_buster' ), 10, 2 );
		add_filter( 'the_content', $n( 'add_cache_buster_post_content' ) );
	}
}

/**
 * Add cache buster query parameter to attachment URL
 *
 * @param  string  $url       Attachment URL
 * @param  integer $attach_id Attachment ID
 * @return string             Modified attachment URL
 */
function add_cache_buster( $url, $attach_id ) {
	$file_version = get_file_version( $attach_id );

	if ( ! $file_version || '' === trim( $file_version ) ) {
		return $url;
	}

	if ( check_file_types( $url ) ) {
		return add_query_arg( 'v', rawurlencode( $file_version ), $url );
	}

	return $url;
}

/**
 * Add Cache Buster parameter to post content links
 * Extracts all links from the $content parameter and pulls its
 * cache busting URL with query parameter
 *
 * @param string $content Post content
 * @return string         Modified post content
 */
function add_cache_buster_post_content( $content ) {

	$links   = check_file_types( wp_extract_urls( $content ) );
	$replace = [];

	if ( ! empty( $links ) ) {
		foreach ( $links as $link ) {
			$busted = add_cache_buster( $link, get_id_by_url( $link ) );

			if ( $busted !== $link ) {
				$replace[ $link ] = $busted;
			}
		}
	}

	if ( ! empty( $replace ) ) {
		$content = str_replace( array_keys( $replace ), array_values( $replace ), $content );
	}

	return $content;
}

/**
 * Check URLs for non-cached file types
 *
 * @param array|string $links Array of URLs or single URL
 * @return array|string       Array of URLs or single URL
 */
function check_file_types( $links ) {
	$dont_cache = apply_filters( 'tyme_no_cache_filetypes', [ 'pdf' ] );
	$filtered   = [];

	if ( is_array( $links ) ) {
		$filtered = array_filter(
			$links,
			function( $link ) use ( $dont_cache ) {
				return wp_check_filetype( basename( $link ), $dont_cache );
			}
		);
	} else {
		return wp_check_filetype( basename( $links ), $dont_cache );
	}

	return $filtered;
}

/**
 * Only add cache buster if file is recently replaced
 * Removes the query string after 5 days of being cached
 *
 * @param  integer $attach_id WP Attachment ID
 * @return boolean
 */
function get_file_version( $attach_id ) {
	return get_post_meta( $attach_id, 'tyme_attachment_replaced', true );
}

/**
 * Get attachment ID by URL
 *
 * @param string $attach_url Attachment URL
 * @return integer           Attachment ID
 */
function get_id_by_url( $attach_url ) {
	$attach_id = false;

	if ( function_exists( 'wpcom_vip_attachment_url_to_postid' ) ) {
		$attach_id = wpcom_vip_attachment_url_to_postid( $attach_url );
	}

	return $attach_id;
}

/**
 * Add Attachment Metadata on Media Replace
 *
 * @param  string $target_url The attachment URL
 * @return string             The attachment URL
 */
function add_replaced_timestamp( $target_url ) {

	if ( check_file_types( $target_url ) ) {
		$attach_id = get_id_by_url( $target_url );

		if ( $attach_id ) {
			update_post_meta( $attach_id, 'tyme_attachment_replaced', strtotime( 'now' ) );
		}
	}

	return $target_url;
}