feat : (#31) add oauthSuccessHandler

Author: qkrwndnjs1075

src/main/kotlin/entry/dsm/gitauth/equusgithubauth/global/oauth/handler/CustomOAuth2AuthenticationSuccessHandler.kt

@@ -0,0 +1,33 @@
+package entry.dsm.gitauth.equusgithubauth.global.oauth.handler
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import jakarta.servlet.http.HttpServletRequest
+import jakarta.servlet.http.HttpServletResponse
+import org.springframework.security.core.Authentication
+import org.springframework.security.web.authentication.AuthenticationSuccessHandler
+import entry.dsm.gitauth.equusgithubauth.global.security.auth.CustomOauth2UserDetails
+
+class CustomOAuth2AuthenticationSuccessHandler(
+    private val objectMapper: ObjectMapper
+) : AuthenticationSuccessHandler {
+
+    override fun onAuthenticationSuccess(
+        request: HttpServletRequest,
+        response: HttpServletResponse,
+        authentication: Authentication
+    ) {
+        // CustomOauth2UserDetails에 저장된 attributes에서 토큰 정보 추출
+        val oauthUser = authentication.principal as? CustomOauth2UserDetails
+        val tokenInfo = oauthUser?.attributes?.let { attributes ->
+            mapOf(
+                "accessToken" to attributes["accessToken"],
+                "accessTokenExpiration" to attributes["accessTokenExpiration"],
+                "refreshToken" to attributes["refreshToken"],
+                "refreshTokenExpiration" to attributes["refreshTokenExpiration"]
+            )
+        }
+        response.contentType = "application/json"
+        response.characterEncoding = "UTF-8"
+        response.writer.write(objectMapper.writeValueAsString(tokenInfo))
+    }
+}