/** Shared auth cookies so storefront + customer.{domain} share one login. */

export const SHARED_ACCESS_TOKEN_KEY = "meshkee_customer_access_token";
export const SHARED_REFRESH_TOKEN_KEY = "meshkee_customer_refresh_token";

const CHUNK_SIZE = 2800;
const MAX_CHUNKS = 24;

function cookieDomain(): string | undefined {
  if (typeof window === "undefined") return undefined;
  const host = window.location.hostname.toLowerCase();
  if (host === "localhost" || host === "127.0.0.1") return undefined;
  const parts = host.split(".").filter(Boolean);
  if (parts.length < 2) return undefined;
  return `.${parts.slice(-2).join(".")}`;
}

function readRawCookie(name: string): string | null {
  if (typeof document === "undefined") return null;
  const prefix = `${name}=`;
  const match = document.cookie.split("; ").find((row) => row.startsWith(prefix));
  if (!match) return null;
  return match.slice(prefix.length);
}

function writeRawCookie(name: string, value: string | null) {
  if (typeof document === "undefined") return;
  const domain = cookieDomain();
  if (value == null) {
    let cookie = `${name}=; path=/; max-age=0; SameSite=Lax`;
    if (domain) cookie += `; domain=${domain}`;
    document.cookie = cookie;
    return;
  }
  const maxAge = 60 * 60 * 24 * 30;
  let cookie = `${name}=${value}; path=/; max-age=${maxAge}; SameSite=Lax`;
  if (domain) cookie += `; domain=${domain}`;
  document.cookie = cookie;
}

function clearChunkedCookie(name: string) {
  writeRawCookie(name, null);
  const n = Number(readRawCookie(`${name}_n`) || "0");
  writeRawCookie(`${name}_n`, null);
  for (let i = 0; i < Math.max(n, MAX_CHUNKS); i++) {
    writeRawCookie(`${name}_${i}`, null);
  }
}

function writeCookie(name: string, value: string | null) {
  clearChunkedCookie(name);
  if (value == null || value === "") return;

  const encoded = encodeURIComponent(value);
  if (encoded.length <= 3500) {
    writeRawCookie(name, encoded);
    return;
  }

  const chunks: string[] = [];
  for (let i = 0; i < encoded.length; i += CHUNK_SIZE) {
    chunks.push(encoded.slice(i, i + CHUNK_SIZE));
  }
  writeRawCookie(`${name}_n`, String(chunks.length));
  chunks.forEach((chunk, i) => writeRawCookie(`${name}_${i}`, chunk));
}

function readCookie(name: string): string | null {
  const n = Number(readRawCookie(`${name}_n`) || "0");
  if (n > 0) {
    let encoded = "";
    for (let i = 0; i < n; i++) {
      const part = readRawCookie(`${name}_${i}`);
      if (part == null) return null;
      encoded += part;
    }
    try {
      return decodeURIComponent(encoded);
    } catch {
      return null;
    }
  }

  const raw = readRawCookie(name);
  if (raw == null) return null;
  try {
    return decodeURIComponent(raw);
  } catch {
    return null;
  }
}

export function writeSharedAuthCookies(accessToken: string, refreshToken?: string) {
  writeCookie(SHARED_ACCESS_TOKEN_KEY, accessToken);
  if (refreshToken) writeCookie(SHARED_REFRESH_TOKEN_KEY, refreshToken);
}

export function clearSharedAuthCookies() {
  writeCookie(SHARED_ACCESS_TOKEN_KEY, null);
  writeCookie(SHARED_REFRESH_TOKEN_KEY, null);
}

export function readSharedAccessToken(): string | null {
  return readCookie(SHARED_ACCESS_TOKEN_KEY);
}

export function readSharedRefreshToken(): string | null {
  return readCookie(SHARED_REFRESH_TOKEN_KEY);
}

export function hydrateLocalTokensFromSharedCookies(
  accessKey = SHARED_ACCESS_TOKEN_KEY,
  refreshKey = SHARED_REFRESH_TOKEN_KEY,
): boolean {
  if (typeof window === "undefined") return false;
  if (localStorage.getItem(accessKey)) return false;
  const access = readSharedAccessToken();
  if (!access) return false;
  localStorage.setItem(accessKey, access);
  const refresh = readSharedRefreshToken();
  if (refresh) localStorage.setItem(refreshKey, refresh);
  return true;
}