import PocketBase from "pocketbase";

const url = process.env.NEXT_PUBLIC_POCKETBASE_URL || "http://127.0.0.1:8090";
const ADMIN_TOKEN_REFRESH_BUFFER_MS = 60_000;

type CachedAdminAuth = {
  token: string;
  expiresAt: number;
};

let cachedAdminAuth: CachedAdminAuth | null = null;

function readJwtExpiryMs(token: string): number {
  const parts = token.split(".");
  if (parts.length < 2) return 0;
  try {
    const payload = JSON.parse(
      Buffer.from(parts[1], "base64url").toString("utf8"),
    ) as { exp?: unknown };
    if (typeof payload.exp !== "number" || !Number.isFinite(payload.exp)) {
      return 0;
    }
    return payload.exp * 1000;
  } catch {
    return 0;
  }
}

function buildPocketBaseWithCachedAuth(): PocketBase | null {
  if (
    !cachedAdminAuth ||
    cachedAdminAuth.expiresAt <= Date.now() + ADMIN_TOKEN_REFRESH_BUFFER_MS
  ) {
    return null;
  }

  const pb = new PocketBase(url);
  // Disable auto-cancellation. The PB SDK's default behaviour is to
  // cancel every in-flight request whenever a new one starts — that
  // works fine for sequential UI calls but breaks any service that
  // fans out reads via Promise.all (e.g. `populateQuoteItemInsights`
  // fires 8 PB queries in parallel and the SDK aborts the first 7 the
  // moment the 8th starts). Safe for admin client: we don't have user
  // cancellation semantics, and the requests are idempotent.
  pb.autoCancellation(false);
  if (pb.authStore && typeof pb.authStore.save === "function") {
    pb.authStore.save(cachedAdminAuth.token);
    return pb;
  }
  return null;
}

export function clearAdminPocketBaseAuthCache(): void {
  cachedAdminAuth = null;
}

export async function getAdminPocketBase() {
  const email = process.env.PB_ADMIN_EMAIL;
  const password = process.env.PB_ADMIN_PASSWORD;

  if (!email || !password) {
    throw new Error("PB_ADMIN_EMAIL and PB_ADMIN_PASSWORD are required for server API operations.");
  }

  const cachedPb = buildPocketBaseWithCachedAuth();
  if (cachedPb) return cachedPb;

  const pb = new PocketBase(url);
  // See buildPocketBaseWithCachedAuth — autoCancellation(false) so
  // Promise.all fan-outs (e.g. populateQuoteItemInsights) don't get
  // aborted mid-flight.
  pb.autoCancellation(false);
  const authData = await pb.collection("_superusers").authWithPassword(email, password);
  cachedAdminAuth = {
    token: authData.token,
    expiresAt: readJwtExpiryMs(authData.token),
  };
  return pb;
}