import {
  createContext,
  useContext,
  useEffect,
  useState,
  type ReactNode,
} from 'react';

/* ===================== 角色（端）上下文 =====================
 * 区分「求职端 candidate」与「企业端 enterprise」两套管路。
 * - 进入 (tabs) 视为求职端，进入 (enterprise) 视为企业端；
 * - identity-select 选定身份时写入 role，两端布局挂载时也会兜底校正。
 *
 * 持久化：当前为会话内（内存）实现，App 重启后回到 null（重新选择身份）。
 * 若已安装 @react-native-async-storage/async-storage，可将文件底部
 * persistRole / loadRole 替换为真实读写，即可跨重启记住当前端。
 */

export type AppRole = 'candidate' | 'enterprise';

interface RoleContextValue {
  role: AppRole | null;
  setRole: (role: AppRole) => void;
  clearRole: () => void;
}

const RoleContext = createContext<RoleContextValue | undefined>(undefined);

let memoryRole: AppRole | null = null;

function persistRole(role: AppRole | null): void {
  memoryRole = role;
  // TODO(持久化): 安装 async-storage 后改为 AsyncStorage.setItem('app_role', role ?? '')
}

function loadRole(): Promise<AppRole | null> {
  return Promise.resolve(memoryRole);
  // TODO(持久化): 安装 async-storage 后改为 AsyncStorage.getItem('app_role')
}

export function RoleProvider({ children }: { children: ReactNode }) {
  const [role, setRoleState] = useState<AppRole | null>(null);

  useEffect(() => {
    let active = true;
    loadRole().then((stored) => {
      if (active && stored) setRoleState(stored);
    });
    return () => {
      active = false;
    };
  }, []);

  const setRole = (next: AppRole) => {
    setRoleState(next);
    persistRole(next);
  };

  const clearRole = () => {
    setRoleState(null);
    persistRole(null);
  };

  return (
    <RoleContext.Provider value={{ role, setRole, clearRole }}>
      {children}
    </RoleContext.Provider>
  );
}

export function useRole(): RoleContextValue {
  const ctx = useContext(RoleContext);
  if (!ctx) {
    throw new Error('useRole 必须在 RoleProvider 内部使用');
  }
  return ctx;
}