@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    public static final String JWT_TOKEN_HEADER_PARAM = "X-Authorization";
    public static final String FORM_BASED_LOGIN_ENTRY_POINT = "/api/auth/login";
    public static final String TOKEN_BASED_AUTH_ENTRY_POINT = "/api/**";
    public static final String TOKEN_REFRESH_ENTRY_POINT = "/api/auth/token";

    @Autowired private RestAuthenticationEntryPoint authenticationEntryPoint;
    @Autowired private AuthenticationSuccessHandler successHandler;
    @Autowired private AuthenticationFailureHandler failureHandler;
    @Autowired private AjaxAuthenticationProvider ajaxAuthenticationProvider;
    @Autowired private JwtAuthenticationProvider jwtAuthenticationProvider;

    @Autowired private TokenExtractor tokenExtractor;

    @Autowired private AuthenticationManager authenticationManager;

    @Autowired private ObjectMapper objectMapper;

    protected AjaxLoginProcessingFilter buildAjaxLoginProcessingFilter() throws Exception {
        AjaxLoginProcessingFilter filter = new AjaxLoginProcessingFilter(FORM_BASED_LOGIN_ENTRY_POINT, successHandler, failureHandler, objectMapper);
        filter.setAuthenticationManager(this.authenticationManager);
        return filter;
    }

    protected JwtTokenAuthenticationProcessingFilter buildJwtTokenAuthenticationProcessingFilter() throws Exception {
        List<String> pathsToSkip = Arrays.asList(TOKEN_REFRESH_ENTRY_POINT, FORM_BASED_LOGIN_ENTRY_POINT);
        SkipPathRequestMatcher matcher = new SkipPathRequestMatcher(pathsToSkip, TOKEN_BASED_AUTH_ENTRY_POINT);
        JwtTokenAuthenticationProcessingFilter filter
            = new JwtTokenAuthenticationProcessingFilter(failureHandler, tokenExtractor, matcher);
        filter.setAuthenticationManager(this.authenticationManager);
        return filter;
    }

    @Bean
    @Override
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }

    @Override
    protected void configure(AuthenticationManagerBuilder auth) {
        auth.authenticationProvider(ajaxAuthenticationProvider);
        auth.authenticationProvider(jwtAuthenticationProvider);
    }

    @Bean
    protected BCryptPasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
        .csrf().disable() // We don't need CSRF for JWT based authentication
        .exceptionHandling()
        .authenticationEntryPoint(this.authenticationEntryPoint)

        .and()
            .sessionManagement()
            .sessionCreationPolicy(SessionCreationPolicy.STATELESS)

        .and()
            .authorizeRequests()
                .antMatchers(FORM_BASED_LOGIN_ENTRY_POINT).permitAll() // Login end-point
                .antMatchers(TOKEN_REFRESH_ENTRY_POINT).permitAll() // Token refresh end-point
                .antMatchers("/console").permitAll() // H2 Console Dash-board - only for testing
        .and()
            .authorizeRequests()
                .antMatchers(TOKEN_BASED_AUTH_ENTRY_POINT).authenticated() // Protected API End-points
        .and()
            .addFilterBefore(buildAjaxLoginProcessingFilter(), UsernamePasswordAuthenticationFilter.class)
            .addFilterBefore(buildJwtTokenAuthenticationProcessingFilter(), UsernamePasswordAuthenticationFilter.class);
    }
}

public class SkipPathRequestMatcher implements RequestMatcher {
    private OrRequestMatcher matchers;
    private RequestMatcher processingMatcher;

    public SkipPathRequestMatcher(List<String> pathsToSkip, String processingPath) {
        Assert.notNull(pathsToSkip);
        List<RequestMatcher> m = pathsToSkip.stream().map(path -> new AntPathRequestMatcher(path)).collect(Collectors.toList());
        matchers = new OrRequestMatcher(m);
        processingMatcher = new AntPathRequestMatcher(processingPath);
    }

    @Override
    public boolean matches(HttpServletRequest request) {
        if (matchers.matches(request)) {
            return false;
        }
        return processingMatcher.matches(request) ? true : false;
    }
}

@Component
public class JwtAuthenticationProvider implements AuthenticationProvider {
    private final JwtSettings jwtSettings;

    @Autowired
    public JwtAuthenticationProvider(JwtSettings jwtSettings) {
        this.jwtSettings = jwtSettings;
    }

    @Override
    public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        RawAccessJwtToken rawAccessToken = (RawAccessJwtToken) authentication.getCredentials();

        Jws<Claims> jwsClaims = rawAccessToken.parseClaims(jwtSettings.getTokenSigningKey());
        String subject = jwsClaims.getBody().getSubject();
        List<String> scopes = jwsClaims.getBody().get("scopes", List.class);
        List<GrantedAuthority> authorities = scopes.stream()
                .map(authority -> new SimpleGrantedAuthority(authority))
                .collect(Collectors.toList());

        UserContext context = UserContext.create(subject, authorities);

        return new JwtAuthenticationToken(context, context.getAuthorities());
    }

    @Override
    public boolean supports(Class<?> authentication) {
        return (JwtAuthenticationToken.class.isAssignableFrom(authentication));
    }
}

@Component
public class JwtHeaderTokenExtractor implements TokenExtractor {
    public static String HEADER_PREFIX = "Bearer ";

    @Override
    public String extract(String header) {
        if (StringUtils.isBlank(header)) {
            throw new AuthenticationServiceException("Authorization header cannot be blank!");
        }

        if (header.length() < HEADER_PREFIX.length()) {
            throw new AuthenticationServiceException("Invalid authorization header size.");
        }

        return header.substring(HEADER_PREFIX.length(), header.length());
    }
}

public class JwtTokenAuthenticationProcessingFilter extends AbstractAuthenticationProcessingFilter {
    private final AuthenticationFailureHandler failureHandler;
    private final TokenExtractor tokenExtractor;

    @Autowired
    public JwtTokenAuthenticationProcessingFilter(AuthenticationFailureHandler failureHandler,
            TokenExtractor tokenExtractor, RequestMatcher matcher) {
        super(matcher);
        this.failureHandler = failureHandler;
        this.tokenExtractor = tokenExtractor;
    }

    @Override
    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
            throws AuthenticationException, IOException, ServletException {
        String tokenPayload = request.getHeader(WebSecurityConfig.JWT_TOKEN_HEADER_PARAM);
        RawAccessJwtToken token = new RawAccessJwtToken(tokenExtractor.extract(tokenPayload));
        return getAuthenticationManager().authenticate(new JwtAuthenticationToken(token));
    }

    @Override
    protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain,
            Authentication authResult) throws IOException, ServletException {
        SecurityContext context = SecurityContextHolder.createEmptyContext();
        context.setAuthentication(authResult);
        SecurityContextHolder.setContext(context);
        chain.doFilter(request, response);
    }

    @Override
    protected void unsuccessfulAuthentication(HttpServletRequest request, HttpServletResponse response,
            AuthenticationException failed) throws IOException, ServletException {
        SecurityContextHolder.clearContext();
        failureHandler.onAuthenticationFailure(request, response, failed);
    }
}

public class AjaxLoginProcessingFilter extends AbstractAuthenticationProcessingFilter {
    private static Logger logger = LoggerFactory.getLogger(AjaxLoginProcessingFilter.class);

    private final AuthenticationSuccessHandler successHandler;
    private final AuthenticationFailureHandler failureHandler;

    private final ObjectMapper objectMapper;

    public AjaxLoginProcessingFilter(String defaultProcessUrl, AuthenticationSuccessHandler successHandler,
            AuthenticationFailureHandler failureHandler, ObjectMapper mapper) {
        super(defaultProcessUrl);
        this.successHandler = successHandler;
        this.failureHandler = failureHandler;
        this.objectMapper = mapper;
    }

    @Override
    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
            throws AuthenticationException, IOException, ServletException {
        if (!HttpMethod.POST.name().equals(request.getMethod()) || !WebUtil.isAjax(request)) {
            if(logger.isDebugEnabled()) {
                logger.debug("Authentication method not supported. Request method: " + request.getMethod());
            }
            throw new AuthMethodNotSupportedException("Authentication method not supported");
        }

        LoginRequest loginRequest = objectMapper.readValue(request.getReader(), LoginRequest.class);

        if (StringUtils.isBlank(loginRequest.getUsername()) || StringUtils.isBlank(loginRequest.getPassword())) {
            throw new AuthenticationServiceException("Username or Password not provided");
        }

        UsernamePasswordAuthenticationToken token = new UsernamePasswordAuthenticationToken(loginRequest.getUsername(), loginRequest.getPassword());

        return this.getAuthenticationManager().authenticate(token);
    }

    @Override
    protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain,
            Authentication authResult) throws IOException, ServletException {
        successHandler.onAuthenticationSuccess(request, response, authResult);
    }

    @Override
    protected void unsuccessfulAuthentication(HttpServletRequest request, HttpServletResponse response,
            AuthenticationException failed) throws IOException, ServletException {
        SecurityContextHolder.clearContext();
        failureHandler.onAuthenticationFailure(request, response, failed);
    }
}

@Component
public class AjaxAuthenticationProvider implements AuthenticationProvider {
    private final BCryptPasswordEncoder encoder;
    private final DatabaseUserService userService;

    @Autowired
    public AjaxAuthenticationProvider(final DatabaseUserService userService, final BCryptPasswordEncoder encoder) {
        this.userService = userService;
        this.encoder = encoder;
    }

    @Override
    public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        Assert.notNull(authentication, "No authentication data provided");

        String username = (String) authentication.getPrincipal();
        String password = (String) authentication.getCredentials();

        User user = userService.getByUsername(username).orElseThrow(() -> new UsernameNotFoundException("User not found: " + username));

        if (!encoder.matches(password, user.getPassword())) {
            throw new BadCredentialsException("Authentication Failed. Username or Password not valid.");
        }

        if (user.getRoles() == null) throw new InsufficientAuthenticationException("User has no roles assigned");

        List<GrantedAuthority> authorities = user.getRoles().stream()
                .map(authority -> new SimpleGrantedAuthority(authority.getRole().authority()))
                .collect(Collectors.toList());

        UserContext userContext = UserContext.create(user.getUsername(), authorities);

        return new UsernamePasswordAuthenticationToken(userContext, null, userContext.getAuthorities());
    }

    @Override
    public boolean supports(Class<?> authentication) {
        return (UsernamePasswordAuthenticationToken.class.isAssignableFrom(authentication));
    }
}