import type { NavigationBudget } from "@umt/contracts";
import { BrowserError } from "./errors.ts";
import { redactBrowserUrl } from "./redact.ts";

/** 主机是否在白名单内:精确匹配或为白名单项的子域。空白名单 = 全部拒绝。 */
export function hostAllowed(host: string, allowlist: readonly string[]): boolean {
  const h = host.toLowerCase().replace(/\.$/, "");
  return allowlist.some((raw) => {
    const d = raw.toLowerCase().replace(/^\*\./, "").replace(/\.$/, "");
    return d !== "" && (h === d || h.endsWith(`.${d}`));
  });
}

/** 导航前检查:只允许 http(s) 且主机在白名单内;违规抛 domain_blocked(信息里只含脱敏 URL) */
export function assertNavigable(url: string, budget: NavigationBudget): URL {
  let u: URL;
  try {
    u = new URL(url);
  } catch {
    throw new BrowserError("bad_request", "非法 URL");
  }
  if (u.protocol !== "http:" && u.protocol !== "https:")
    throw new BrowserError("domain_blocked", `不允许的协议 ${u.protocol}`);
  if (!hostAllowed(u.hostname, budget.domainAllowlist))
    throw new BrowserError("domain_blocked", `域名不在白名单:${redactBrowserUrl(u.origin)}`);
  return u;
}