/** تشخیص host پلتفرم در برابر ساب‌دامین tenant. */

const DEFAULT_BASE =
  process.env.NEXT_PUBLIC_PLATFORM_BASE_DOMAIN || "torbatyar.ir";

const RESERVED = new Set([
  "www",
  "api",
  "auth",
  "identity",
  "admin",
  "app",
  "mail",
  "webmail",
]);

export interface TenantHostInfo {
  hostname: string;
  baseDomain: string;
  /** اگر روی ساب‌دامین tenant باشیم */
  isTenantHost: boolean;
  slug: string | null;
  /** دامنه apex پلتفرم */
  isPlatformHost: boolean;
}

export function getBaseDomain(): string {
  return DEFAULT_BASE.toLowerCase();
}

export function resolveTenantHost(
  hostname?: string,
  baseDomain: string = getBaseDomain()
): TenantHostInfo {
  const host = (hostname || (typeof window !== "undefined" ? window.location.hostname : "") || "")
    .split(":")[0]
    .trim()
    .toLowerCase();
  const base = baseDomain.toLowerCase();

  if (!host || host === "localhost" || host === "127.0.0.1") {
    return {
      hostname: host || "localhost",
      baseDomain: base,
      isTenantHost: false,
      slug: null,
      isPlatformHost: true,
    };
  }

  if (host === base || host === `www.${base}`) {
    return {
      hostname: host,
      baseDomain: base,
      isTenantHost: false,
      slug: null,
      isPlatformHost: true,
    };
  }

  if (host.endsWith(`.${base}`)) {
    const sub = host.slice(0, -(base.length + 1));
    if (sub && !sub.includes(".") && !RESERVED.has(sub)) {
      return {
        hostname: host,
        baseDomain: base,
        isTenantHost: true,
        slug: sub,
        isPlatformHost: false,
      };
    }
  }

  // دامنه اختصاصی احتمالی — فعلاً مثل tenant host با slug=null؛ API از Host resolve می‌کند
  return {
    hostname: host,
    baseDomain: base,
    isTenantHost: true,
    slug: null,
    isPlatformHost: false,
  };
}