"use client";

import { createContext, useCallback, useContext, useEffect, useMemo, useState } from "react";
import { usePathname, useRouter } from "next/navigation";
import type { AuthMode, AuthUser } from "@/lib/auth/session";
import { fetchBrowserAuthState, safeBrowserLocationNext, type BrowserCurrentSession } from "@/lib/client/browser-auth";

type BrowserAuthStatus = "loading" | "ready" | "error";

type BrowserAuthState = {
  status: BrowserAuthStatus;
  user: AuthUser | null;
  authMode: AuthMode | null;
  authRequired: boolean;
  authConfigured: boolean;
  isAdmin: boolean;
  isSuperAdmin: boolean;
  error: string | null;
  refresh: () => Promise<void>;
};

const BrowserAuthContext = createContext<BrowserAuthState | null>(null);

export function BrowserAuthProvider({ children }: { children: React.ReactNode }) {
  const [session, setSession] = useState<BrowserCurrentSession | null>(null);
  const [status, setStatus] = useState<BrowserAuthStatus>("loading");
  const [error, setError] = useState<string | null>(null);

  const loadSession = useCallback(async (signal?: AbortSignal) => {
    try {
      const current = await fetchBrowserAuthState(signal);
      setSession(current);
      setStatus("ready");
      setError(null);
    } catch (cause) {
      if (cause instanceof DOMException && cause.name === "AbortError") return;
      setStatus("error");
      setError(cause instanceof Error ? cause.message : "无法读取认证状态");
    }
  }, []);

  useEffect(() => {
    const controller = new AbortController();
    void loadSession(controller.signal);
    return () => controller.abort();
  }, [loadSession]);

  const value = useMemo<BrowserAuthState>(() => {
    const user = session?.user || null;
    const authRequired = session?.authRequired ?? true;
    const isSuperAdmin = !authRequired || user?.role === "super_admin";
    const isAdmin = isSuperAdmin || user?.role === "organization_admin";
    return {
      status,
      user,
      authMode: session?.authMode || null,
      authRequired,
      authConfigured: session?.authConfigured ?? false,
      isAdmin,
      isSuperAdmin,
      error,
      refresh: () => loadSession()
    };
  }, [error, loadSession, session, status]);

  return <BrowserAuthContext.Provider value={value}>{children}</BrowserAuthContext.Provider>;
}

export function useBrowserAuth(): BrowserAuthState {
  const state = useContext(BrowserAuthContext);
  if (!state) throw new Error("useBrowserAuth must be used inside BrowserAuthProvider");
  return state;
}

export function BrowserAuthGuard({
  children,
  role = "user"
}: {
  children: React.ReactNode;
  role?: "user" | "admin" | "super";
}) {
  const auth = useBrowserAuth();
  const pathname = usePathname();
  const router = useRouter();
  const needsLogin = auth.status === "ready" && auth.authRequired && !auth.user;

  useEffect(() => {
    if (needsLogin) {
      const next = safeBrowserLocationNext(window.location, pathname || "/create");
      router.replace(`/auth/login?next=${encodeURIComponent(next)}`);
    }
  }, [needsLogin, pathname, router]);

  if (auth.status === "loading" || needsLogin) {
    return <AuthStatePanel message="正在确认登录状态…" />;
  }
  if (auth.status === "error") {
    return <AuthStatePanel message={auth.error || "无法读取认证状态"} actionLabel="重试" onAction={() => void auth.refresh()} />;
  }
  if ((role === "admin" && !auth.isAdmin) || (role === "super" && !auth.isSuperAdmin)) {
    return <AuthStatePanel message="当前账号无权访问此页面。" />;
  }
  return <>{children}</>;
}

export function ClientRedirect({ to, forwardNext = false }: { to: string; forwardNext?: boolean }) {
  useEffect(() => {
    const next = forwardNext ? new URLSearchParams(window.location.search).get("next") : null;
    const destination = next ? `${to}?next=${encodeURIComponent(next)}` : to;
    window.location.replace(destination);
  }, [forwardNext, to]);
  return <AuthStatePanel message="正在跳转…" />;
}

function AuthStatePanel({
  message,
  actionLabel,
  onAction
}: {
  message: string;
  actionLabel?: string;
  onAction?: () => void;
}) {
  return (
    <section className="panel">
      <p className="muted">{message}</p>
      {actionLabel && onAction ? <button className="button" type="button" onClick={onAction}>{actionLabel}</button> : null}
    </section>
  );
}