import { request, unwrapApiBody, type ApiResponse } from "../utils/http/factory";

export type AuthUser = {
  id: number;
  username: string;
  role: string;
  publicSlug: string | null;
  nickname: string | null;
  avatar: string | null;
};

type MeResult = {
  user: AuthUser;
};

type SessionResult = {
  user: AuthUser | null;
};

export type AuthSessionState = {
  initialized: boolean;
  pending: boolean;
  loggedIn: boolean;
  user: AuthUser | null;
};

export const AUTH_SESSION_STATE_KEY = "auth:session";
/** 客户端是否已做过与 Cookie 的一次强制对齐（`ensureClientMeSynced`）；登出等场景需重置 */
export const AUTH_CLIENT_ME_SYNCED_KEY = "auth:client-me-synced";
export const DEFAULT_AUTH_SESSION_STATE: AuthSessionState = {
  initialized: false,
  pending: false,
  loggedIn: false,
  user: null,
};

function isUnauthorized(error: unknown) {
  if (typeof error !== "object" || error === null) {
    return false;
  }
  return "statusCode" in error && (error as { statusCode?: number }).statusCode === 401;
}

export function useAuthSession() {
  const state = useState<AuthSessionState>(AUTH_SESSION_STATE_KEY, () => ({
    ...DEFAULT_AUTH_SESSION_STATE,
  }));
  const clientMeSynced = useState<boolean>(AUTH_CLIENT_ME_SYNCED_KEY, () => false);

  const applyUser = (user: AuthUser | null) => {
    state.value.user = user;
    state.value.loggedIn = Boolean(user);
    state.value.initialized = true;
  };

  const clear = () => {
    clientMeSynced.value = false;
    applyUser(null);
  };

  const refresh = async (force = false) => {
    if (state.value.initialized && !force) {
      return state.value.user;
    }
    if (state.value.pending) {
      return state.value.user;
    }
    state.value.pending = true;
    try {
      const fetcher = import.meta.server ? useRequestFetch() : request;
      const payload = await fetcher<ApiResponse<MeResult>>("/api/auth/me");
      const data = unwrapApiBody(payload);
      applyUser(data.user);
      return data.user;
    } catch (error: unknown) {
      if (isUnauthorized(error)) {
        clear();
        return null;
      }
      throw error;
    } finally {
      state.value.pending = false;
    }
  };

  /**
   * 全站 SPA 生命周期内至多同步一次客户端会话（`GET /api/auth/session`）。
   * 无会话 Cookie 时服务端不查库；有 Cookie 时与 `/api/auth/me` 相比少一次额外查询。
   */
  const ensureClientMeSynced = async (): Promise<void> => {
    if (import.meta.server || clientMeSynced.value) {
      return;
    }
    try {
      const payload = await request<ApiResponse<SessionResult>>("/api/auth/session");
      const data = unwrapApiBody(payload);
      applyUser(data.user);
      clientMeSynced.value = true;
    } catch {
      /* 网络错误等：保留 SSR 状态，下次进入带壳页面可再试 */
    }
  };

  return {
    initialized: computed(() => state.value.initialized),
    loggedIn: computed(() => state.value.loggedIn),
    user: computed(() => state.value.user),
    pending: computed(() => state.value.pending),
    refresh,
    clear,
    ensureClientMeSynced,
  };
}