/**
 * Pure helpers for app boot / onboarding loader visibility.
 * Kept free of React so unit tests can assert real decision logic
 * without mounting the full app tree.
 */

export const PUBLIC_AUTH_PATHS = new Set([
  "/",
  "/login",
  "/signup",
  "/forgot-password",
  "/reset-password",
  "/privacy",
  "/terms",
  "/refund",
  "/refunds",
  "/contact",
  "/feedback",
  "/report-bug",
  "/logout",
  "/pricing",
  "/preview/tuition",
  "/preview/chapter/sound-waves",
]);

const PUBLIC_AUTH_PREFIXES = [
  "/auth/",
  "/compare/",
  "/flashcards/",
  "/kerala-plus-one",
  "/kerala-plus-two",
  "/learn/",
  "/quiz/",
  "/revision/",
] as const;

/**
 * Known signed-in app surfaces. Auth gates must use this allowlist so
 * unknown URLs fall through to Next.js `not-found` instead of login?next=.
 */
const PROTECTED_APP_PATHS = new Set([
  "/onboarding",
  "/dashboard",
  "/home",
  "/home-next",
  "/tuition",
  "/study-chat",
  "/learn-anything",
  "/bookmarks",
  "/classes",
  "/notifications",
  "/pyq-analyzer",
  "/analytics",
  "/documents",
  "/exam-coach",
  "/first-hour",
  "/generate",
  "/last-night",
  "/library",
  "/missions",
  "/mode-selection",
  "/notes",
  "/previous-papers",
  "/profile",
  "/progress",
  "/quizzes",
  "/settings",
  "/sources",
  "/syllabus",
  "/teach",
  "/upload",
  "/video",
  "/videos",
  "/video-generator",
]);

const PROTECTED_APP_PREFIXES = [
  "/admin",
  "/onboarding",
  "/dashboard",
  "/home",
  "/home-next",
  "/tuition",
  "/study-chat",
  "/learn-anything",
  "/bookmarks",
  "/classes",
  "/notifications",
  "/pyq-analyzer",
  "/analytics",
  "/documents",
  "/exam-coach",
  "/first-hour",
  "/generate",
  "/last-night",
  "/library",
  "/missions",
  "/mode-selection",
  "/notes",
  "/previous-papers",
  "/profile",
  "/progress",
  "/quizzes",
  "/settings",
  "/sources",
  "/syllabus",
  "/teach",
  "/upload",
  "/video",
  "/videos",
  "/video-generator",
] as const;

export function isPublicAuthPath(pathname: string | null | undefined): boolean {
  if (!pathname) return true;
  if (PUBLIC_AUTH_PATHS.has(pathname)) return true;
  if (pathname === "/learn") return true;
  return PUBLIC_AUTH_PREFIXES.some((prefix) => pathname.startsWith(prefix));
}

function matchesPathOrPrefix(pathname: string, prefix: string): boolean {
  return pathname === prefix || pathname.startsWith(`${prefix}/`);
}

/**
 * True only for known workspace / admin app routes.
 * Unknown paths are intentionally false so RootLoadingGuard does not
 * intercept them into login — Next.js not-found handles those.
 */
export function isProtectedAppPath(pathname: string | null | undefined): boolean {
  if (!pathname) return false;
  if (isPublicAuthPath(pathname)) return false;
  if (PROTECTED_APP_PATHS.has(pathname)) return true;
  return PROTECTED_APP_PREFIXES.some((prefix) =>
    matchesPathOrPrefix(pathname, prefix),
  );
}

export type AppLoadingInput = {
  hasAuthContext: boolean;
  isAuthLoading: boolean;
  isRedirecting: boolean;
  pathname: string | null | undefined;
};

/**
 * Full-screen branded boot loader.
 * - Always when auth context is missing (provider not ready).
 * - Always while an onboarding redirect is in flight.
 * - Never over marketing/auth pages during a routine session probe
 *   (those pages should paint immediately).
 * - Never over unknown URLs (real 404 must paint, not workspace loader).
 * - On known protected student routes while auth is still resolving.
 */
export function shouldShowAppLoadingScreen(input: AppLoadingInput): boolean {
  if (!input.hasAuthContext) return true;
  if (input.isRedirecting) return true;
  if (!isProtectedAppPath(input.pathname)) return false;
  return input.isAuthLoading;
}

/**
 * Whether the real route tree may render under the boot guard.
 * Public pages and unknown URLs render even while auth is probing;
 * known protected routes wait.
 */
export function shouldRenderAppChildren(input: AppLoadingInput): boolean {
  if (!input.hasAuthContext) return false;
  if (input.isRedirecting) return false;
  if (!isProtectedAppPath(input.pathname)) return true;
  return !input.isAuthLoading;
}

export type OnboardingRedirectTarget = "/onboarding" | "/home" | null;

export function resolveProtectedRouteRedirect(input: {
  hasUser: boolean;
  isAuthLoading: boolean;
  pathname: string | null | undefined;
}): string | null {
  const path = input.pathname ?? "/";
  if (input.isAuthLoading || input.hasUser) return null;
  if (!isProtectedAppPath(path)) return null;
  const candidate = path.startsWith("/") && !path.startsWith("//") ? path : "/home";
  const authLoop =
    candidate === "/login" ||
    candidate === "/signup" ||
    candidate === "/logout" ||
    candidate.startsWith("/login?") ||
    candidate.startsWith("/signup?") ||
    candidate.startsWith("/logout?") ||
    candidate.startsWith("/login/") ||
    candidate.startsWith("/signup/") ||
    candidate.startsWith("/logout/");
  const safeNext = authLoop ? "/home" : candidate;
  return `/login?next=${encodeURIComponent(safeNext)}`;
}

/**
 * Resolve post-auth onboarding redirects.
 * `onboardingComplete === null` means the async check is still pending.
 */
export function resolveOnboardingRedirect(input: {
  hasUser: boolean;
  isAuthLoading: boolean;
  pathname: string | null | undefined;
  onboardingComplete: boolean | null;
}): OnboardingRedirectTarget {
  if (input.isAuthLoading || !input.hasUser) return null;
  if (input.onboardingComplete === null) return null;

  const path = input.pathname ?? "/";
  if (!input.onboardingComplete && path !== "/onboarding" && isProtectedAppPath(path)) {
    return "/onboarding";
  }
  if (input.onboardingComplete && path === "/onboarding") {
    return "/home";
  }
  return null;
}

/** Ease fake progress toward a soft cap — never claims 100% before unmount. */
export function nextBootProgress(current: number, cap = 94): number {
  if (current >= cap) return cap;
  const step = Math.max(1, Math.round((cap - current) * 0.12));
  return Math.min(cap, current + step);
}

export const BOOT_STATUS_MESSAGES = [
  "Starting DocDoe…",
  "Checking your session…",
  "Opening your workspace…",
  "Almost ready…",
] as const;

export function bootStatusForProgress(progress: number): string {
  if (progress < 28) return BOOT_STATUS_MESSAGES[0];
  if (progress < 55) return BOOT_STATUS_MESSAGES[1];
  if (progress < 82) return BOOT_STATUS_MESSAGES[2];
  return BOOT_STATUS_MESSAGES[3];
}