OpenIsle/src/main/java/com/openisle/controller/CommentController.java

package com.openisle.controller;

import com.openisle.model.Comment;
import com.openisle.service.CommentService;
import lombok.Data;
import lombok.RequiredArgsConstructor;
import org.springframework.http.ResponseEntity;
import org.springframework.security.core.Authentication;
import org.springframework.web.bind.annotation.*;

import java.time.LocalDateTime;
import java.util.List;
import java.util.stream.Collectors;

/*
curl -X POST http://localhost:8080/api/posts/1/comments \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer <token>" \
    -d '{ "content": "Nice post" }'

curl -X POST http://localhost:8080/api/comments/1/replies \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer <token>" \
    -d '{ "content": "Thanks!" }'

curl http://localhost:8080/api/posts/1/comments \
    -H "Authorization: Bearer <token>"
 */

@RestController
@RequestMapping("/api")
@RequiredArgsConstructor
public class CommentController {
    private final CommentService commentService;

    @PostMapping("/posts/{postId}/comments")
    public ResponseEntity<CommentDto> createComment(@PathVariable Long postId,
                                                    @RequestBody CommentRequest req,
                                                    Authentication auth) {
        Comment comment = commentService.addComment(auth.getName(), postId, req.getContent());
        return ResponseEntity.ok(toDto(comment));
    }

    @PostMapping("/comments/{commentId}/replies")
    public ResponseEntity<CommentDto> replyComment(@PathVariable Long commentId,
                                                   @RequestBody CommentRequest req,
                                                   Authentication auth) {
        Comment comment = commentService.addReply(auth.getName(), commentId, req.getContent());
        return ResponseEntity.ok(toDto(comment));
    }

    @GetMapping("/posts/{postId}/comments")
    public List<CommentDto> listComments(@PathVariable Long postId) {
        return commentService.getCommentsForPost(postId).stream()
                .map(this::toDtoWithReplies)
                .collect(Collectors.toList());
    }

    private CommentDto toDtoWithReplies(Comment comment) {
        CommentDto dto = toDto(comment);
        List<CommentDto> replies = commentService.getReplies(comment.getId()).stream()
                .map(this::toDtoWithReplies)
                .collect(Collectors.toList());
        dto.setReplies(replies);
        return dto;
    }

    private CommentDto toDto(Comment comment) {
        CommentDto dto = new CommentDto();
        dto.setId(comment.getId());
        dto.setContent(comment.getContent());
        dto.setCreatedAt(comment.getCreatedAt());
        dto.setAuthor(comment.getAuthor().getUsername());
        return dto;
    }

    @Data
    private static class CommentRequest {
        private String content;
    }

    @Data
    private static class CommentDto {
        private Long id;
        private String content;
        private LocalDateTime createdAt;
        private String author;
        private List<CommentDto> replies;
    }
}