export const COOKIE_NAME = "loggedin_session";
export const SESSION_ID_RE = /^[0-9a-f]{32}$/;
export const COOKIE_MAX_AGE_SEC = 7 * 24 * 60 * 60;

export function newSessionId(): string {
  const bytes = new Uint8Array(16);
  crypto.getRandomValues(bytes);
  return [...bytes].map((b) => b.toString(16).padStart(2, "0")).join("");
}

export function parseSessionId(cookieHeader: string | null): string | null {
  if (!cookieHeader) return null;
  for (const part of cookieHeader.split(";")) {
    const trimmed = part.trim();
    const eq = trimmed.indexOf("=");
    if (eq === -1) continue;
    const name = trimmed.slice(0, eq);
    const value = trimmed.slice(eq + 1);
    if (name === COOKIE_NAME && SESSION_ID_RE.test(value)) return value;
  }
  return null;
}

export function sessionCookieHeader(id: string, secure: boolean): string {
  if (secure) {
    return `${COOKIE_NAME}=${id}; Path=/; HttpOnly; Secure; SameSite=None; Max-Age=${COOKIE_MAX_AGE_SEC}`;
  }
  return `${COOKIE_NAME}=${id}; Path=/; HttpOnly; SameSite=Lax; Max-Age=${COOKIE_MAX_AGE_SEC}`;
}