/**
 * Names, slugs and wikilinks.
 *
 * Every note is addressed three ways: its file name in the vault (what
 * Obsidian wikilinks resolve), its slug (what the URL uses), and its type.
 * These helpers are the only place those rules live.
 */

/** Characters Obsidian or common file systems refuse in a file name. */
const UNSAFE_FILE_CHARS = /[\\/:*?"<>|#^[\]]/g;

/** A file name (without `.md`) safe for Obsidian on every platform. */
export function safeFileName(title: string): string {
  return title
    .replace(UNSAFE_FILE_CHARS, " ")
    .replace(/\s+/g, " ")
    .trim()
    .replace(/[. ]+$/, "");
}

/** URL slug from a title: lowercase ASCII words joined by hyphens. */
export function slugify(text: string): string {
  return text
    .normalize("NFKD")
    .replace(/[̀-ͯ]/g, "")
    .toLowerCase()
    .replace(/&/g, " and ")
    .replace(/['’]/g, "")
    .replace(/[^a-z0-9]+/g, "-")
    .replace(/^-+|-+$/g, "");
}

const WIKILINK = /^\[\[([^[\]|#]+)(?:#[^[\]|]*)?(?:\|[^[\]]*)?\]\]$/;
const WIKILINK_GLOBAL = /\[\[([^[\]|#]+)(?:#[^[\]|]*)?(?:\|[^[\]]*)?\]\]/g;

/** `Name` → `[[Name]]`. */
export function toWikilink(target: string): string {
  return `[[${target}]]`;
}

/** `[[Name|alias]]` → `Name`, or null when the value is not a wikilink. */
export function wikilinkTarget(value: string): string | null {
  const m = WIKILINK.exec(value.trim());
  return m ? m[1]!.trim() : null;
}

/** Every wikilink target in a block of Markdown, in order, without repeats. */
export function wikilinksIn(markdown: string): string[] {
  const seen = new Set<string>();
  for (const m of markdown.matchAll(WIKILINK_GLOBAL)) seen.add(m[1]!.trim());
  return [...seen];
}

/**
 * An unquoted `[[Name]]` in YAML parses as a nested list (`[["Name"]]`).
 * Obsidian quotes them, but hand edits may not, so accept both shapes.
 */
export function normalizeWikilinkInput(value: unknown): unknown {
  if (Array.isArray(value) && value.length === 1 && Array.isArray(value[0]) && value[0].length === 1) {
    const inner = value[0][0];
    if (typeof inner === "string") return toWikilink(inner);
  }
  return value;
}