// author: simon-pierre boucher <contact@spboucher.ai>
export const SAFARI_UA =
  "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4 Safari/605.1.15";

export const BOT_SUFFIX = " Tendril/1.0 (+https://www.ten-dril.com/bot)";

export const DEFAULT_USER_AGENT = SAFARI_UA + BOT_SUFFIX;

/**
 * Build request headers in Safari's emission order (§3.2). Header order is a
 * fingerprint, so this returns an insertion-ordered object; do not sort it.
 * The bot suffix in the UA is non-negotiable (§26).
 */
export function buildHeaders(
  host: string,
  overrides?: Readonly<Record<string, string>>,
  userAgent?: string,
): Record<string, string> {
  const headers: Record<string, string> = {
    Host: host,
    Accept: "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
    "Accept-Language": "en-US,en;q=0.9",
    "Accept-Encoding": "gzip, deflate, br",
    "User-Agent": (userAgent ?? SAFARI_UA) + BOT_SUFFIX,
    Connection: "keep-alive",
    "Sec-Fetch-Dest": "document",
    "Sec-Fetch-Mode": "navigate",
    "Sec-Fetch-Site": "none",
    "Sec-Fetch-User": "?1",
    "Upgrade-Insecure-Requests": "1",
  };
  if (overrides) {
    for (const [key, value] of Object.entries(overrides)) headers[key] = value;
  }
  return headers;
}