oEmbed Provider Generator

<?php
/**
 * oEmbed providers.
 *
 * Adds services WordPress does not ship a provider for, so a bare URL on its own
 * line becomes an embed.
 *
 * WordPress can also find an endpoint by itself: it fetches the page and looks for
 * a <link rel="alternate" type="application/json+oembed"> tag. That is discovery,
 * it is on by default, and it means a provider entry is only needed when the
 * service does not advertise an endpoint, when discovery has been turned off, or
 * when you want the embed to work without the extra request.
 */

defined( 'ABSPATH' ) || exit;

add_action( 'init', 'my_plugin_register_oembed_providers' );

/**
 * Registers the providers.
 *
 * On init rather than at file load: wp_oembed_add_provider() writes into the
 * oEmbed singleton, and calling it too early is how a provider silently goes
 * missing.
 *
 * @return void
 */
function my_plugin_register_oembed_providers() {
	// Loom.
	wp_oembed_add_provider(
		'https://www.loom.com/share/*',
		'https://www.loom.com/v1/oembed',
		false
	);

}

add_action( 'init', 'my_plugin_maybe_clear_oembed_cache' );

/**
 * Clears cached oEmbed results after a provider change.
 *
 * Results are cached twice: in post meta, as _oembed_<hash> on the post that
 * contains the URL, and in a transient for the HTTP response. Changing a provider
 * does not touch either, which is why an edit often appears to do nothing at all.
 *
 * Bump the version constant below to clear them once.
 *
 * @return void
 */
function my_plugin_maybe_clear_oembed_cache() {
	$version = '1';

	if ( get_option( 'my_plugin_oembed_version' ) === $version ) {
		return;
	}

	global $wpdb;

	// Post meta first: these are what the editor and the front end read.
	$wpdb->query(
		"DELETE FROM {$wpdb->postmeta} WHERE meta_key LIKE '\_oembed\_%'"
	);

	update_option( 'my_plugin_oembed_version', $version );
}