package kr.itn.itnhub.feed;

import kr.itn.itnhub.mattermost.MattermostClient;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.List;

/**
 * 기관관리 상세의 게시물/자료 탭이 부르는 읽기 전용 엔드포인트.
 * 브라우저는 Mattermost를 절대 직접 호출하지 않고 전부 이 컨트롤러를 거친다.
 */
@RestController
public class ChannelFeedController {

    private final ChannelFeedService feedService;
    private final MattermostClient mattermost;

    public ChannelFeedController(ChannelFeedService feedService, MattermostClient mattermost) {
        this.feedService = feedService;
        this.mattermost = mattermost;
    }

    @GetMapping("/api/orgs/{id}/posts")
    public List<PostView> posts(@PathVariable Long id, @RequestParam String channel) {
        return feedService.posts(id, channel);
    }

    @GetMapping("/api/orgs/{id}/files")
    public List<FileView> files(@PathVariable Long id, @RequestParam String channel) {
        return feedService.files(id, channel);
    }

    /**
     * 한글 파일명이 대부분이라 {@code Content-Disposition}은 반드시 RFC 5987의
     * {@code filename*=UTF-8''...} 형식으로 인코딩해야 한다. 일반 {@code filename="..."}
     * 만 쓰면 브라우저마다 한글이 깨진다.
     */
    @GetMapping("/api/files/{fileId}")
    public ResponseEntity<byte[]> download(@PathVariable String fileId) {
        FileRef info = mattermost.fileInfo(fileId);
        byte[] content = mattermost.downloadFile(fileId);

        String encodedName = URLEncoder.encode(info.name(), StandardCharsets.UTF_8)
                .replace("+", "%20");
        MediaType contentType = resolveContentType(info.mimeType());

        return ResponseEntity.ok()
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename*=UTF-8''" + encodedName)
                .contentType(contentType)
                .body(content);
    }

    private MediaType resolveContentType(String mimeType) {
        if (mimeType == null || mimeType.isBlank()) {
            return MediaType.APPLICATION_OCTET_STREAM;
        }
        try {
            return MediaType.parseMediaType(mimeType);
        } catch (org.springframework.util.InvalidMimeTypeException e) {
            return MediaType.APPLICATION_OCTET_STREAM;
        }
    }
}