/**
 * Builds the patterns of the search queries' `LIKE`, for the dump, playlist
 * and user searches. A query's `%` and `_` are matched as themselves rather
 * than as wildcards: usernames hold underscores, and "a_b" must not find
 * "axb".
 *
 * @module
 */

/**
 * Returns the pattern matching text that contains `query`, or that starts
 * with it when `where` is `"prefix"`. The SQL must read `LIKE ? ESCAPE '\'`,
 * which the {@link LIKE} fragment spells.
 */
export function likePattern(
  query: string,
  where: "anywhere" | "prefix" = "anywhere",
): string {
  const escaped = query.replace(/[\\%_]/g, "\\$&");
  return where === "prefix" ? `${escaped}%` : `%${escaped}%`;
}

/** Spells `LIKE ? ESCAPE '\'`, for a {@link likePattern} parameter. */
export const LIKE = "LIKE ? ESCAPE '\\'";