Attempt to fix oEmbed in WordPress - doesn't work because certain oEmbed providers won't give you HTTPS-suitable content

fix-oembed.php

# Fix oEmbed for HTTPS
add_filter('oembed_providers', function ($providers) {
  $new_providers = array();

  foreach ($providers as $key => $value) {
    $matchmask = $key;
    $providerurl = $value[0];
    $regex = $value[1];

    # Convert simple-style to full regex (assuming all regexes use # as delimiter)
    if (!$regex) {
      # wp-includes/class-oembed.php line 79
      $matchmask = '#' . str_replace( '___wildcard___', '(.+)', preg_quote( str_replace( '*', '___wildcard___', $matchmask ), '#' ) ) . '#i';
    }

    # Make regex match HTTPS too (note that some URIs already match for /https?/)
    if (substr($matchmask, 0, 9) !== '#https?://') {
      $matchmask = preg_replace('_^#http://_', '#https?://', $matchmask);
    }

    # Make oEmbed URL HTTPS
    $providerurl = preg_replace('_^http://_', 'https://', $providerurl);

    # Add it
    $new_providers[$matchmask] = array($providerurl, true);
  }

  return $new_providers;
});