/*
在指定筛选器类的位置添加筛选器。例如，如果希望筛选器 CustomFilter 注册到与 相同的 UsernamePasswordAuthenticationFilter位置，则可以调用：
    addFilterAt(new CustomFilter(), UsernamePasswordAuthenticationFilter.class)
在同一位置注册多个筛选器意味着它们的排序不是确定的。更具体地说，在同一位置注册多个筛选器不会覆盖现有筛选器。相反，不要注册您不想使用的筛选器。
形参:
过滤器 – 要注册的过滤器
atFilter – 已在 Spring Security 注册（即已知）的另一个 Filter 位置。
返回值:
用于 HttpSecurity 进一步的定制
*/
public HttpSecurity addFilterAt(Filter filter, Class<? extends Filter> atFilter) {
    return addFilterAtOffsetOf(filter, 0, atFilter);
}

/*
处理身份验证表单提交。在 Spring Security 3.0 之前调用 AuthenticationProcessingFilter 。
登录表单必须向此筛选器提供两个参数：用户名和密码。要使用的默认参数名称包含在静态字段 SPRING_SECURITY_FORM_USERNAME_KEY 和 SPRING_SECURITY_FORM_PASSWORD_KEY中。还可以通过设置 usernameParameter and passwordParameter 属性来更改参数名称。
默认情况下，此过滤器响应 URL /login。
自:
3.0
作者:
本·亚历克斯、科林·桑帕莱亚努、卢克·泰勒
*/
public class UsernamePasswordAuthenticationFilter extends AbstractAuthenticationProcessingFilter {
    public static final String SPRING_SECURITY_FORM_USERNAME_KEY = "username";
    public static final String SPRING_SECURITY_FORM_PASSWORD_KEY = "password";
    private static final AntPathRequestMatcher DEFAULT_ANT_PATH_REQUEST_MATCHER = new AntPathRequestMatcher("/login",
                                                                                                            "POST");
    private String usernameParameter = SPRING_SECURITY_FORM_USERNAME_KEY;
    private String passwordParameter = SPRING_SECURITY_FORM_PASSWORD_KEY;
    private boolean postOnly = true;
    public UsernamePasswordAuthenticationFilter() {
        super(DEFAULT_ANT_PATH_REQUEST_MATCHER);
    }
    public UsernamePasswordAuthenticationFilter(AuthenticationManager authenticationManager) {
        super(DEFAULT_ANT_PATH_REQUEST_MATCHER, authenticationManager);
    }
}

/**
 * 自定义前后端分离认证 Filter
 */
public class LoginFilter extends UsernamePasswordAuthenticationFilter {
    @Override
    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response) throws AuthenticationException {
        /**
         * 需要做的三件事
         */
        //1. 判断是否为post的请求
        if (!request.getMethod().equals("POST")) {
            throw new AuthenticationServiceException("请求方法不支持" + request.getMethod());
        }
        //2. 判断是否为json格式的数据
        if (request.getContentType().equalsIgnoreCase(MediaType.APPLICATION_JSON_VALUE)) {
            //2.1  提取用户名 ，密码
            try {
                /**
                 * 用流的形式去接收
                 * 因为源码中有
                 private String usernameParameter = "username";
                 private String passwordParameter = "password";
                 所以我们可以直接继承下来 使用
                 */
                Map<String, String> userInfo = new ObjectMapper().readValue(request.getInputStream(), Map.class);
                String username = userInfo.get(getUsernameParameter());
                String password = userInfo.get(getPasswordParameter());
                //已经获取到了username...
                //2.2 按照源码的实例， 我们就需要将获取的内容封装为一个token
                // UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(username, password);
                UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(username, password);
                setDetails(request, authRequest);
                //最后调用本类中的authenticate
                return this.getAuthenticationManager().authenticate(authRequest);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        //3. 将json格式的数据中 获取我们需要的username ， password进行认证
        return super.attemptAuthentication(request, response);
    }
}

/**
 * 自定义Filter交给容器进行管理
 * 基本是按照源码中的内容去进行配置
 */
@Bean
public LoginFilter loginFilter() throws Exception {
    LoginFilter loFilter = new LoginFilter();
    loFilter.setFilterProcessesUrl("/doLogin");
    //其中的value属性与 前端form表单中输入用户名的name属性相同
    loFilter.setUsernameParameter("username");
    loFilter.setPasswordParameter("password");
    //注入自己的AuthenticationManager
    loFilter.setAuthenticationManager(authenticationManagerBean());
    //认证成功处理 。认证失败处理
    loFilter.setAuthenticationSuccessHandler((request, response, authentication) -> {
        Map<String, Object> result = new HashMap<>();
        result.put("msg", "登录成功！");
        result.put("status", "200");
        result.put("用户信息", (User) authentication.getPrincipal());
        response.setContentType("application/json;charset=UTF-8");
        String s = new ObjectMapper().writeValueAsString(result);
        response.getWriter().println(s);
    });
    loFilter.setAuthenticationFailureHandler((request, response, exception) -> {
        Map<String, Object> result = new HashMap<>();
        result.put("msg", "登录失败！！");
        result.put("status", "400");
        result.put("错误信息", exception.getMessage());
        response.setContentType("application/json;charset=UTF-8");
        String s = new ObjectMapper().writeValueAsString(result);
        response.getWriter().println(s);
    });
    return loFilter;
}

//注入自己的AuthenticationManager
loFilter.setAuthenticationManager(authenticationManagerBean());

@Component
public class MyUserDetailsService implements UserDetailsService {
    private final UserDao userDao;
    @Autowired
    public MyUserDetailsService(UserDao userDao) {
        this.userDao = userDao;
    }
    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        User user = userDao.loadUserByUsername(username);
        if (ObjectUtils.isEmpty(user)) throw new UsernameNotFoundException("用户名不正确！");
        //存在的话 ， 赋予权限信息
        List<Role> roles = userDao.getRolesByUid(user.getId());
        user.setRoles(roles);
        return user;
    }
}

/**
 * 创建自己userDetailsService，然后交给AuthenticationManagerBuilder来创建我们自己的AuthenticationManager
 */
private final MyUserDetailsService myUserDetailsService;
@Autowired
public testConfig(MyUserDetailsService myUserDetailsService) {
    this.myUserDetailsService = myUserDetailsService;
}

* 创建自己的AuthenticationManager
 */
@Override
protected void configure(AuthenticationManagerBuilder auth) throws Exception {
    auth.userDetailsService(myUserDetailsService);
}

/**
 * 将自定义的认证暴露在工厂中 （加入到容器中去管理）
 */
@Override
@Bean
public AuthenticationManager authenticationManagerBean() throws Exception {
    return super.authenticationManagerBean();
}

@Override
protected void configure(HttpSecurity http) throws Exception {
    //前后端分离，数据从json中提取
    http.authorizeRequests()
        .anyRequest().authenticated()
        .and()
        .formLogin().loginPage("/loginPages")
        .and()
        .csrf().disable()
        ;
    /**
         * 将我们自定义的filter过滤器替换其中的某个过滤器(filter)
         *loginFilter() ---change---> UsernamePasswordAuthenticationFilter
         */
    http.addFilterAt(loginFilter(), UsernamePasswordAuthenticationFilter.class);
}