#97 - Add OAuth authentication configuration

Add configuration to allow Spring Security to accept both existing DB authentication and OAuth authentication.

src/main/java/com/laphayen/projectboard/config/SecurityConfig.java

@@ -1,53 +1,98 @@
 package com.laphayen.projectboard.config;
 
-import com.laphayen.projectboard.dto.UserAccountDto;
 import com.laphayen.projectboard.dto.security.BoardPrincipal;
-import com.laphayen.projectboard.repository.UserAccountRepository;
+import com.laphayen.projectboard.dto.security.KakaoOAuth2Response;
+import com.laphayen.projectboard.service.UserAccountService;
 import org.springframework.boot.autoconfigure.security.reactive.PathRequest;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpMethod;
-import org.springframework.security.config.Customizer;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.core.userdetails.UserDetailsService;
 import org.springframework.security.core.userdetails.UsernameNotFoundException;
 import org.springframework.security.crypto.factory.PasswordEncoderFactories;
 import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.security.oauth2.client.userinfo.DefaultOAuth2UserService;
+import org.springframework.security.oauth2.client.userinfo.OAuth2UserRequest;
+import org.springframework.security.oauth2.client.userinfo.OAuth2UserService;
+import org.springframework.security.oauth2.core.user.OAuth2User;
 import org.springframework.security.web.SecurityFilterChain;
 
+import java.util.UUID;
+
+import static org.springframework.security.config.Customizer.withDefaults;
+
 @Configuration
 public class SecurityConfig {
 
     @Bean
-    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
-       http
-               .authorizeHttpRequests(auth -> auth
-                       .requestMatchers(String.valueOf(PathRequest.toStaticResources().atCommonLocations())).permitAll()
-                       .requestMatchers(
-                               HttpMethod.GET,
-                               "/",
-                               "/articles",
-                               "/articles/search-hashtag",
-                               "/css/**","/scripts/**","/plugin/**","/fonts/**"
-                       ).permitAll()
-                       .anyRequest().authenticated()
-               )
-               .formLogin(Customizer.withDefaults())
-               .logout(logout -> logout
-                       .logoutSuccessUrl("/")
-               );
-       return http.build();
+    public SecurityFilterChain securityFilterChain(
+            HttpSecurity http,
+            OAuth2UserService<OAuth2UserRequest, OAuth2User> oAuth2UserService
+    ) throws Exception {
+        return http
+                .authorizeHttpRequests(auth -> auth
+                        .requestMatchers(String.valueOf(PathRequest.toStaticResources().atCommonLocations())).permitAll()
+                        .requestMatchers(
+                                HttpMethod.GET,
+                                "/",
+                                "/articles",
+                                "/articles/search-hashtag",
+                                "/css/**","/scripts/**","/plugin/**","/fonts/**"
+                        ).permitAll()
+                        .anyRequest().authenticated()
+                )
+                .formLogin(withDefaults())
+                .logout(logout -> logout.logoutSuccessUrl("/"))
+                .oauth2Login(oAuth -> oAuth
+                        .userInfoEndpoint(userInfo -> userInfo
+                                .userService(oAuth2UserService)
+                        )
+                )
+                .build();
     }
 
     @Bean
-    public UserDetailsService userDetailsService(UserAccountRepository userAccountRepository) {
-        return username -> userAccountRepository
-                .findById(username)
-                .map(UserAccountDto::from)
+    public UserDetailsService userDetailsService(UserAccountService userAccountService) {
+        return username -> userAccountService
+                .searchUser(username)
                 .map(BoardPrincipal::from)
                 .orElseThrow(() -> new UsernameNotFoundException("유저를 찾을 수 없습니다 - username: " + username));
     }
 
+    @Bean
+    public OAuth2UserService<OAuth2UserRequest, OAuth2User> oAuth2UserService(
+            UserAccountService userAccountService,
+            PasswordEncoder passwordEncoder
+    ) {
+        final DefaultOAuth2UserService delegate = new DefaultOAuth2UserService();
+
+        return userRequest -> {
+            OAuth2User oAuth2User = delegate.loadUser(userRequest);
+
+            KakaoOAuth2Response kakaoResponse = KakaoOAuth2Response.from(oAuth2User.getAttributes());
+            String registrationId = userRequest.getClientRegistration().getRegistrationId();
+            String providerId = String.valueOf(kakaoResponse.id());
+            String username = registrationId + "_" + providerId;
+            String dummyPassword = passwordEncoder.encode("{bcrypt}" + UUID.randomUUID());
+
+            return userAccountService.searchUser(username)
+                    .map(BoardPrincipal::from)
+                    .orElseGet(() ->
+                            BoardPrincipal.from(
+                                    userAccountService.saveUser(
+                                            username,
+                                            dummyPassword,
+                                            kakaoResponse.email(),
+                                            kakaoResponse.nickname(),
+                                            null
+                                    )
+                            )
+                    );
+        };
+
+    }
+
     @Bean
     public PasswordEncoder passwordEncoder() {
         return PasswordEncoderFactories.createDelegatingPasswordEncoder();