'use client';

import * as React from 'react';
import {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useRef,
  useState,
} from 'react';
import { toast } from 'sonner';
import type {
  AdminUser,
  CreateUserRequest,
  ListUsersRequest,
  UpdateUserRequest,
} from '@/lib/services/admin';
import services from '@/lib/services';

/** 用户列表查询参数 */
export interface UserQueryParams {
  page: number;
  page_size: number;
  user_id?: string;
  username?: string;
  email?: string;
  status?: 'all' | 'active' | 'inactive';
}

/** Admin Users Context State Interface */
interface AdminUsersContextState {
  users: AdminUser[];
  total: number;
  loading: boolean;
  error: Error | null;

  // Params
  page: number;
  pageSize: number;
  searchUserId: string;
  searchUsername: string;
  searchEmail: string;
  statusFilter: 'all' | 'active' | 'inactive';

  // Actions
  setPage: (page: number) => void;
  setPageSize: (size: number) => void;
  setSearchUserId: (userId: string) => void;
  setSearchUsername: (username: string) => void;
  setSearchEmail: (email: string) => void;
  setStatusFilter: (status: 'all' | 'active' | 'inactive') => void;

  fetchUsers: (force?: boolean) => Promise<void>;
  refresh: () => Promise<void>;
  getUserDetail: (id: string) => Promise<AdminUser>;
  updateUserStatus: (user: AdminUser) => Promise<void>;
  createUser: (req: CreateUserRequest) => Promise<AdminUser>;
  updateUser: (id: string, req: UpdateUserRequest) => Promise<void>;
  deleteUser: (user: AdminUser) => Promise<void>;
}

const CACHE_DURATION = 5 * 60 * 1000; // 5 minutes cache

const AdminUsersContext = createContext<AdminUsersContextState | null>(null);

export function AdminUsersProvider({
  children,
}: {
  children: React.ReactNode;
}) {
  // State
  const [users, setUsers] = useState<AdminUser[]>([]);
  const [total, setTotal] = useState(0);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<Error | null>(null);

  // Query Params State
  const [page, setPage] = useState(1);
  const [pageSize, setPageSize] = useState(20);
  const [searchUserId, setSearchUserId] = useState('');
  const [searchUsername, setSearchUsername] = useState('');
  const [searchEmail, setSearchEmail] = useState('');
  const [statusFilter, setStatusFilter] = useState<
    'all' | 'active' | 'inactive'
  >('all');
  const [debouncedSearchUserId, setDebouncedSearchUserId] = useState('');
  const [debouncedSearchUsername, setDebouncedSearchUsername] = useState('');
  const [debouncedSearchEmail, setDebouncedSearchEmail] = useState('');

  // Cache
  const cacheRef = useRef<
    Record<string, { data: AdminUser[]; total: number; timestamp: number }>
  >({});
  const latestRequestIdRef = useRef(0);

  // Debounce search
  useEffect(() => {
    const timer = setTimeout(() => {
      setDebouncedSearchUserId(searchUserId);
      setDebouncedSearchUsername(searchUsername);
      setDebouncedSearchEmail(searchEmail);
      if (
        searchUserId !== debouncedSearchUserId ||
        searchUsername !== debouncedSearchUsername ||
        searchEmail !== debouncedSearchEmail
      ) {
        setPage(1); // Reset to page 1 on search change
      }
    }, 500);
    return () => clearTimeout(timer);
  }, [
    searchUserId,
    searchUsername,
    searchEmail,
    debouncedSearchUserId,
    debouncedSearchUsername,
    debouncedSearchEmail,
  ]);

  const generateCacheKey = (params: UserQueryParams) => {
    return JSON.stringify(params);
  };

  const fetchUsers = useCallback(
    async (force = false) => {
      const params: UserQueryParams = {
        page,
        page_size: pageSize,
        user_id: debouncedSearchUserId || undefined,
        username: debouncedSearchUsername || undefined,
        email: debouncedSearchEmail || undefined,
        status: statusFilter,
      };

      const cacheKey = generateCacheKey(params);
      const now = Date.now();
      const cached = cacheRef.current[cacheKey];

      // Use cache if valid and not forced
      if (!force && cached && now - cached.timestamp < CACHE_DURATION) {
        setUsers(cached.data);
        setTotal(cached.total);
        setLoading(false);
        setError(null);
        return;
      }

      setLoading(true);
      setError(null);
      const requestId = ++latestRequestIdRef.current;

      try {
        // Current API doesn't support status filter in listUsers?
        // The previous implementation did client-side filtering.
        // Ideally backend supports it. If not, we fetch and filter?
        // "services.adminUser.listUsers" in previous code only took page, page_size, username.
        // So status filter was client side.
        // However, caching client-filtered result is tricky if we don't have all data.
        // But previous implementation fetched *paged* data then filtered? No, that would be wrong (filtering 20 items might leave 0).
        // Let's check previous implementation:
        // "const data = await services.adminUser.listUsers(...) ... let filteredUsers = data.users ... if (statusFilter...) filtered..."
        // This means filtering happens ONLY on the current page of results! This is technically buggy if the user wants "all inactive users".
        // But preserving that behavior for now.

        const requestParams: ListUsersRequest = {
          page,
          page_size: pageSize,
          user_id: debouncedSearchUserId || undefined,
          username: debouncedSearchUsername || undefined,
          email: debouncedSearchEmail || undefined,
        };

        const response = await services.adminUser.listUsers(requestParams);

        if (requestId !== latestRequestIdRef.current) return;

        let resultUsers = response.users;
        // Client-side filtering as per previous logic (though restrictive)
        if (statusFilter === 'active') {
          resultUsers = resultUsers.filter((u) => u.is_active);
        } else if (statusFilter === 'inactive') {
          resultUsers = resultUsers.filter((u) => !u.is_active);
        }

        setUsers(resultUsers);
        setTotal(response.total); // Note: Total might be inaccurate if we filter client side! But per previous code...

        // Update cache
        cacheRef.current[cacheKey] = {
          data: resultUsers,
          total: response.total,
          timestamp: now,
        };
      } catch (err) {
        if (requestId !== latestRequestIdRef.current) return;
        setError(
          err instanceof Error ? err : new Error('Failed to fetch users'),
        );
      } finally {
        if (requestId === latestRequestIdRef.current) {
          setLoading(false);
        }
      }
    },
    [
      page,
      pageSize,
      debouncedSearchUserId,
      debouncedSearchUsername,
      debouncedSearchEmail,
      statusFilter,
    ],
  );

  // Removed auto-fetch useEffect. Consumer (UsersManager) should trigger fetch.

  const refresh = async () => {
    await fetchUsers(true);
  };

  const updateUserStatus = async (user: AdminUser) => {
    const originalStatus = user.is_active;

    // Optimistic update
    setUsers((prev) =>
      prev.map((u) =>
        u.id === user.id ? { ...u, is_active: !u.is_active } : u,
      ),
    );

    // Clear cache because data changed
    cacheRef.current = {};

    try {
      await services.adminUser.updateUserStatus(user.id, {
        is_active: !user.is_active,
      });
      toast.success(
        `已${!user.is_active ? '启用' : '禁用'}用户 ${user.username}`,
      );
    } catch {
      // Revert on error
      setUsers((prev) =>
        prev.map((u) =>
          u.id === user.id ? { ...u, is_active: originalStatus } : u,
        ),
      );
      toast.error('更新状态失败');
    }
  };

  const getUserDetail = async (id: string) => {
    return services.adminUser.getUser(id);
  };

  const createUser = async (req: CreateUserRequest) => {
    try {
      const newUser = await services.adminUser.createUser(req);
      setUsers((prev) => [newUser, ...prev]);
      setTotal((prev) => prev + 1);
      // Clear cache because data changed
      cacheRef.current = {};
      toast.success(`已成功创建用户 ${newUser.username}`);
      return newUser;
    } catch (err) {
      toast.error(err instanceof Error ? err.message : '创建用户失败');
      throw err;
    }
  };

  const deleteUser = async (user: AdminUser) => {
    try {
      await services.adminUser.deleteUser(user.id);
      setUsers((prev) => prev.filter((u) => u.id !== user.id));
      setTotal((prev) => Math.max(0, prev - 1));
      cacheRef.current = {};
      toast.success(`已删除用户 ${user.username}`);
    } catch (err) {
      toast.error(err instanceof Error ? err.message : '删除用户失败');
      throw err;
    }
  };

  const updateUser = async (id: string, req: UpdateUserRequest) => {
    try {
      await services.adminUser.updateUser(id, req);
      setUsers((prev) => prev.map((u) => (u.id === id ? { ...u, ...req } : u)));
      cacheRef.current = {};
      toast.success('更新用户信息成功');
    } catch (err) {
      toast.error(err instanceof Error ? err.message : '更新用户信息失败');
      throw err;
    }
  };

  const value = {
    users,
    total,
    loading,
    error,
    page,
    pageSize,
    searchUserId,
    searchUsername,
    searchEmail,
    statusFilter,
    setPage,
    setPageSize,
    setSearchUserId,
    setSearchUsername,
    setSearchEmail,
    setStatusFilter,
    fetchUsers,
    refresh,
    getUserDetail,
    updateUserStatus,
    createUser,
    updateUser,
    deleteUser,
  };

  return (
    <AdminUsersContext.Provider value={value}>
      {children}
    </AdminUsersContext.Provider>
  );
}

export function useAdminUsers() {
  const context = useContext(AdminUsersContext);
  if (!context) {
    throw new Error('useAdminUsers must be used within an AdminUsersProvider');
  }
  return context;
}