VIP Go File service layer for Photonfill

vipgo_photonfill.php

<?php
/**
 * VIP: make the Photonfill plugin working with the VIP Go file service instead of WPCOM's Photon.
 */
 
// Hijack the photonfill prefix.
add_filter( 'photonfill_hook_prefix', function( $prefix ) {
    return 'vipgo';
} );

// Rewrite arguments to the ones used by VIP Go File service.
add_filter( 'jetpack_photon_pre_args', function( $args, $image_url, $scheme ) {
    $key_mapping = array(
        'width' => 'w',
        'height' => 'h',
    );
    foreach( $key_mapping as $old_key => $new_key ) {
        if ( false === array_key_exists( $new_key, $args ) && true === array_key_exists( $old_key, $args ) ) {
            $args[$new_key] = $args[$old_key];
            unset( $args[$old_key] );
        }
    }
    
    // Remove args which are not needed on VIP Go Fileservice
    $blacklisted_keys = array(
        'attachment_id',
    );
    foreach( $blacklisted_keys as $blacklisted_key ) {
        unset( $args[$blacklisted_key] );
    }
    return $args;
}, 10 ,3 );

// Use Jetpack's function for generating the photon URL and modify the output the way it references the VIP Go file service.
function vipgo_photon_url( $image_url, $args = array(), $scheme = null ) {

    $jetpack_photon_url = jetpack_photon_url( $image_url, $args, $scheme );

    // Remove the Photon URL part.
    foreach( array( 0, 1, 2 ) as $subdomain ) {
        $vipgo_photon_url = str_replace( "https://i{$subdomain}.wp.com", 'https:/', $jetpack_photon_url );
    }

    // Remove the ssl arg.
    $vipgo_photon_url = add_query_arg( 'ssl', false, $vipgo_photon_url );

    return $vipgo_photon_url;
}