preg_replace_all() example to replace Drupal 7 [scald] tags with Drupal 10 <drupal-media> tags

scald-to-media.php

<?php

$input_lines = "My normal[scald=1:sdl_editor_representation][scald=2:sdl_editor_representation]
more texthere haha[scald=3:sql_editor_representation]this_does not work!";

// Match all [scald] tags and pull out the IDs.
preg_match_all('/\[scald=(\d+).*?\]/u', $input_lines, $output_array);

$output_lines = $input_lines;
foreach ($output_array[0] as $index => $scald_tag) {
  $scald_id = $output_array[0][$index];
  $uuid = $scald_id; // Convert Scald ID to media UUID here.
  // Replace the [scald] tag with a <drupal-media> tag in the output.
  str_replace($scald_tag, '<drupal-media data-entity-type="media" data-entity-uuid="' . $uuid . '">&nbsp;</drupal-media>', $output_lines);
}

return $output_lines;