// What <UserMenu> shows of the signed-in user: the name and e-mail authelia
// reports, the initials avatar built from them, and the authelia pages the
// menu links. Pure, so the swarm UI's tests can run it.

export interface WhoAmI {
  displayName: string | null;
  email: string | null;
}

// The seven chromatic theme colours the avatar is picked from, by name.
const AVATAR_ACCENTS = [
  "var(--red)",
  "var(--yellow)",
  "var(--green)",
  "var(--cyan)",
  "var(--blue)",
  "var(--purple)",
  "var(--pink)",
];

/** A colour for `seed`: the same name always gets the same one. */
export function pickAccent(seed: string): string {
  let hash = 0;
  for (let i = 0; i < seed.length; i++)
    hash = (hash * 31 + seed.charCodeAt(i)) | 0;
  return AVATAR_ACCENTS[Math.abs(hash) % AVATAR_ACCENTS.length];
}

/**
 * Lenient parse of authelia's `GET /api/user/info`, which wraps its answer in
 * a `{status, data}` envelope. The menu is cosmetic, so a shape that is not
 * recognised gives no name rather than an error.
 */
export function parseWhoAmI(body: unknown): WhoAmI {
  const record = (body ?? {}) as Record<string, unknown>;
  const data = (record.data ?? record) as Record<string, unknown>;
  const displayName =
    typeof data.display_name === "string" ? data.display_name : null;
  const emails = Array.isArray(data.emails) ? data.emails : null;
  const email =
    emails && typeof emails[0] === "string" ? (emails[0] as string) : null;
  return { displayName, email };
}

/** The name to show: the display name, else the e-mail, else none. */
export function labelOf(who: WhoAmI | null): string | null {
  return who?.displayName || who?.email || null;
}

/** The letter in the avatar, or "?" when there is no name. */
export function initialOf(label: string | null): string {
  return label ? label.trim().charAt(0).toUpperCase() : "?";
}

/** Authelia's settings and sign-out pages under `autheliaUrl`, if it is known. */
export function accountLinks(
  autheliaUrl: string | null,
): { settings: string; logout: string } | null {
  if (!autheliaUrl) return null;
  // The trailing slash comes off so `/settings` appends cleanly.
  const base = autheliaUrl.replace(/\/+$/, "");
  return { settings: `${base}/settings`, logout: `${base}/logout` };
}