feat: 블로그 핵심 기능 구현 (댓글, 태그, 카테고리, 이미지)

[댓글 시스템]
- 계층형(대댓글) 구조 및 회원/비회원 하이브리드 작성 로직 구현
- 비회원 댓글용 비밀번호 암호화 저장 (PasswordEncoder 적용)
- 관리자용 댓글 강제 삭제 및 전체 댓글 모니터링(Dashboard) API 구현

[태그 & 카테고리]
- N:M 태그 시스템(PostTag) 엔티티 설계 및 게시글 작성 시 자동 저장 로직
- 계층형(Tree) 카테고리 구조 구현 및 관리자 생성/삭제 API
- QueryDSL 검색 조건에 태그 및 카테고리 필터링 추가

[이미지 업로드]
- AWS S3 (MinIO) 연동 및 Bucket 자동 생성/Public 정책 설정
- 마크다운 에디터용 이미지 업로드 API 구현

src/main/kotlin/me/wypark/blogbackend/api/controller/CategoryController.kt

@@ -0,0 +1,21 @@
+package me.wypark.blogbackend.api.controller
+
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.api.dto.CategoryResponse
+import me.wypark.blogbackend.domain.category.CategoryService
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+@RequestMapping("/api/categories")
+class CategoryController(
+    private val categoryService: CategoryService
+) {
+
+    @GetMapping
+    fun getCategoryTree(): ResponseEntity<ApiResponse<List<CategoryResponse>>> {
+        return ResponseEntity.ok(ApiResponse.success(categoryService.getCategoryTree()))
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/controller/CommentController.kt

@@ -0,0 +1,49 @@
+package me.wypark.blogbackend.api.controller
+
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.api.dto.CommentDeleteRequest
+import me.wypark.blogbackend.api.dto.CommentResponse
+import me.wypark.blogbackend.api.dto.CommentSaveRequest
+import me.wypark.blogbackend.domain.comment.CommentService
+import org.springframework.http.ResponseEntity
+import org.springframework.security.core.annotation.AuthenticationPrincipal
+import org.springframework.security.core.userdetails.User
+import org.springframework.web.bind.annotation.*
+
+@RestController
+@RequestMapping("/api/comments")
+class CommentController(
+    private val commentService: CommentService
+) {
+
+    // 댓글 목록 조회
+    @GetMapping
+    fun getComments(@RequestParam postSlug: String): ResponseEntity<ApiResponse<List<CommentResponse>>> {
+        return ResponseEntity.ok(ApiResponse.success(commentService.getComments(postSlug)))
+    }
+
+    // 댓글 작성 (회원 or 비회원)
+    @PostMapping
+    fun createComment(
+        @RequestBody request: CommentSaveRequest,
+        @AuthenticationPrincipal user: User? // 비회원이면 null이 들어옴
+    ): ResponseEntity<ApiResponse<Long>> {
+        val email = user?.username // null이면 비회원
+        val commentId = commentService.createComment(request, email)
+        return ResponseEntity.ok(ApiResponse.success(commentId, "댓글이 등록되었습니다."))
+    }
+
+    // 댓글 삭제
+    @DeleteMapping("/{id}")
+    fun deleteComment(
+        @PathVariable id: Long,
+        @RequestBody(required = false) request: CommentDeleteRequest?, // 비회원용 비밀번호 바디
+        @AuthenticationPrincipal user: User?
+    ): ResponseEntity<ApiResponse<Nothing>> {
+        val email = user?.username
+        val password = request?.guestPassword
+
+        commentService.deleteComment(id, email, password)
+        return ResponseEntity.ok(ApiResponse.success(message = "댓글이 삭제되었습니다."))
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/controller/PostController.kt

@@ -0,0 +1,38 @@
+package me.wypark.blogbackend.api.controller
+
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.api.dto.PostResponse
+import me.wypark.blogbackend.api.dto.PostSummaryResponse
+import me.wypark.blogbackend.domain.post.PostService
+import org.springframework.data.domain.Page
+import org.springframework.data.domain.Pageable
+import org.springframework.data.domain.Sort
+import org.springframework.data.web.PageableDefault
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.*
+
+@RestController
+@RequestMapping("/api/posts")
+class PostController(
+    private val postService: PostService
+) {
+
+    // 목록 조회 (기본값: 최신순, 10개씩)
+    @GetMapping
+    fun getPosts(
+        @RequestParam(required = false) keyword: String?,
+        @RequestParam(required = false) category: String?,
+        @RequestParam(required = false) tag: String?, // 👈 파라미터 추가
+        @PageableDefault(size = 10, sort = ["id"], direction = Sort.Direction.DESC) pageable: Pageable
+    ): ResponseEntity<ApiResponse<Page<PostSummaryResponse>>> {
+
+        val result = postService.searchPosts(keyword, category, tag, pageable)
+        return ResponseEntity.ok(ApiResponse.success(result))
+    }
+
+    // 상세 조회 (Slug)
+    @GetMapping("/{slug}")
+    fun getPost(@PathVariable slug: String): ResponseEntity<ApiResponse<PostResponse>> {
+        return ResponseEntity.ok(ApiResponse.success(postService.getPostBySlug(slug)))
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/controller/admin/AdminCategoryController.kt

@@ -0,0 +1,26 @@
+package me.wypark.blogbackend.api.controller.admin
+
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.api.dto.CategoryCreateRequest
+import me.wypark.blogbackend.domain.category.CategoryService
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.*
+
+@RestController
+@RequestMapping("/api/admin/categories")
+class AdminCategoryController(
+    private val categoryService: CategoryService
+) {
+
+    @PostMapping
+    fun createCategory(@RequestBody request: CategoryCreateRequest): ResponseEntity<ApiResponse<Long>> {
+        val id = categoryService.createCategory(request)
+        return ResponseEntity.ok(ApiResponse.success(id, "카테고리가 생성되었습니다."))
+    }
+
+    @DeleteMapping("/{id}")
+    fun deleteCategory(@PathVariable id: Long): ResponseEntity<ApiResponse<Nothing>> {
+        categoryService.deleteCategory(id)
+        return ResponseEntity.ok(ApiResponse.success(message = "카테고리가 삭제되었습니다."))
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/controller/admin/AdminCommentController.kt

@@ -0,0 +1,33 @@
+package me.wypark.blogbackend.api.controller.admin
+
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.api.dto.AdminCommentResponse
+import me.wypark.blogbackend.api.dto.CommentResponse
+import me.wypark.blogbackend.domain.comment.CommentService
+import org.springframework.data.domain.Page
+import org.springframework.data.domain.Pageable
+import org.springframework.data.domain.Sort
+import org.springframework.data.web.PageableDefault
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.*
+
+@RestController
+@RequestMapping("/api/admin/comments")
+class AdminCommentController(
+    private val commentService: CommentService
+) {
+
+    // 관리자 권한으로 댓글 삭제
+    @DeleteMapping("/{id}")
+    fun deleteComment(@PathVariable id: Long): ResponseEntity<ApiResponse<Nothing>> {
+        commentService.deleteCommentByAdmin(id)
+        return ResponseEntity.ok(ApiResponse.success(message = "관리자 권한으로 댓글을 삭제했습니다."))
+    }
+
+    @GetMapping
+    fun getAllComments(
+        @PageableDefault(size = 20, sort = ["id"], direction = Sort.Direction.DESC) pageable: Pageable
+    ): ResponseEntity<ApiResponse<Page<AdminCommentResponse>>> {
+        return ResponseEntity.ok(ApiResponse.success(commentService.getAllComments(pageable)))
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/controller/admin/AdminImageController.kt

@@ -0,0 +1,26 @@
+package me.wypark.blogbackend.api.controller.admin
+
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.domain.image.ImageService
+import org.springframework.http.MediaType
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RequestPart
+import org.springframework.web.bind.annotation.RestController
+import org.springframework.web.multipart.MultipartFile
+
+@RestController
+@RequestMapping("/api/admin/images")
+class AdminImageController(
+    private val imageService: ImageService
+) {
+
+    @PostMapping(consumes = [MediaType.MULTIPART_FORM_DATA_VALUE])
+    fun uploadImage(
+        @RequestPart("image") image: MultipartFile
+    ): ResponseEntity<ApiResponse<String>> {
+        val imageUrl = imageService.uploadImage(image)
+        return ResponseEntity.ok(ApiResponse.success(imageUrl, "이미지 업로드 성공"))
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/controller/admin/AdminPostController.kt

@@ -0,0 +1,30 @@
+package me.wypark.blogbackend.api.controller.admin
+
+import jakarta.validation.Valid
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.api.dto.PostSaveRequest
+import me.wypark.blogbackend.domain.post.PostService
+import org.springframework.http.ResponseEntity
+import org.springframework.security.core.annotation.AuthenticationPrincipal
+import org.springframework.security.core.userdetails.User
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RequestBody
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+@RequestMapping("/api/admin/posts")
+class AdminPostController(
+    private val postService: PostService
+) {
+
+    @PostMapping
+    fun createPost(
+        @RequestBody @Valid request: PostSaveRequest,
+        @AuthenticationPrincipal user: User
+    ): ResponseEntity<ApiResponse<Long>> {
+        // user.username은 email입니다.
+        val postId = postService.createPost(request, user.username)
+        return ResponseEntity.ok(ApiResponse.success(postId, "게시글이 작성되었습니다."))
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/dto/CategoryDtos.kt

@@ -0,0 +1,51 @@
+package me.wypark.blogbackend.api.dto
+
+import me.wypark.blogbackend.domain.category.Category
+
+// [요청] 카테고리 생성
+data class CategoryCreateRequest(
+    val name: String,
+    val parentId: Long? = null // null이면 최상위(Root) 카테고리
+)
+
+// [응답] 카테고리 트리 구조 (재귀)
+data class CategoryResponse(
+    val id: Long,
+    val name: String,
+    val children: List<CategoryResponse> // 자식들
+) {
+    companion object {
+        // Entity -> DTO 변환 (재귀 호출)
+        fun from(category: Category): CategoryResponse {
+            return CategoryResponse(
+                id = category.id!!,
+                name = category.name,
+                // 자식들을 DTO로 변환하여 리스트에 담음
+                children = category.children.map { from(it) }
+            )
+        }
+    }
+}
+
+// [Admin용 응답] 관리자 대시보드 목록용
+data class AdminCommentResponse(
+    val id: Long,
+    val content: String,
+    val author: String,
+    val postTitle: String, // 어떤 글인지 식별
+    val postSlug: String,  // 클릭 시 해당 글로 이동용
+    val createdAt: java.time.LocalDateTime
+) {
+    companion object {
+        fun from(comment: me.wypark.blogbackend.domain.comment.Comment): AdminCommentResponse {
+            return AdminCommentResponse(
+                id = comment.id!!,
+                content = comment.content,
+                author = comment.getAuthorName(),
+                postTitle = comment.post.title,
+                postSlug = comment.post.slug,
+                createdAt = comment.createdAt
+            )
+        }
+    }
+}

src/main/kotlin/me/wypark/blogbackend/api/dto/CommentDtos.kt

@@ -0,0 +1,41 @@
+package me.wypark.blogbackend.api.dto
+
+import me.wypark.blogbackend.domain.comment.Comment
+import java.time.LocalDateTime
+
+// [응답] 댓글 (계층형 구조)
+data class CommentResponse(
+    val id: Long,
+    val content: String,
+    val author: String, // 회원 닉네임 또는 비회원 닉네임
+    val createdAt: LocalDateTime,
+    val children: List<CommentResponse> // 대댓글 리스트
+) {
+    companion object {
+        fun from(comment: Comment): CommentResponse {
+            return CommentResponse(
+                id = comment.id!!,
+                content = comment.content,
+                author = comment.getAuthorName(), // Entity에 만들어둔 편의 메서드 사용
+                createdAt = comment.createdAt,
+                children = comment.children.map { from(it) } // 재귀적으로 자식 변환
+            )
+        }
+    }
+}
+
+// [요청] 댓글 작성
+data class CommentSaveRequest(
+    val postSlug: String,
+    val content: String,
+    val parentId: Long? = null, // 대댓글일 경우 부모 ID
+
+    // 비회원 전용 필드 (회원은 null 가능)
+    val guestNickname: String? = null,
+    val guestPassword: String? = null
+)
+
+// [요청] 댓글 삭제 (비회원용 비밀번호 전달)
+data class CommentDeleteRequest(
+    val guestPassword: String? = null
+)

src/main/kotlin/me/wypark/blogbackend/api/dto/PostDtos.kt

@@ -0,0 +1,62 @@
+package me.wypark.blogbackend.api.dto
+
+import me.wypark.blogbackend.domain.post.Post
+import java.time.LocalDateTime
+
+// [응답] 게시글 상세 정보
+data class PostResponse(
+    val id: Long,
+    val title: String,
+    val content: String,
+    val slug: String,
+    val categoryName: String?,
+    val viewCount: Long,
+    val createdAt: LocalDateTime
+) {
+    // Entity -> DTO 변환 편의 메서드
+    companion object {
+        fun from(post: Post): PostResponse {
+            return PostResponse(
+                id = post.id!!,
+                title = post.title,
+                content = post.content,
+                slug = post.slug,
+                categoryName = post.category?.name,
+                viewCount = post.viewCount,
+                createdAt = post.createdAt
+            )
+        }
+    }
+}
+
+// [응답] 게시글 목록용 (본문 제외, 가볍게)
+data class PostSummaryResponse(
+    val id: Long,
+    val title: String,
+    val slug: String,
+    val categoryName: String?,
+    val viewCount: Long,
+    val createdAt: LocalDateTime
+) {
+    companion object {
+        fun from(post: Post): PostSummaryResponse {
+            return PostSummaryResponse(
+                id = post.id!!,
+                title = post.title,
+                slug = post.slug,
+                categoryName = post.category?.name,
+                viewCount = post.viewCount,
+                createdAt = post.createdAt
+            )
+        }
+    }
+}
+
+// [요청] 게시글 작성/수정
+data class PostSaveRequest(
+    val title: String,
+    val content: String, // 마크다운 원문
+    val slug: String,
+    val categoryId: Long? = null,
+    val tags: List<String> = emptyList() // 태그는 나중에 구현
+)