src/main/java/com/pt/service/TorrentService.java

package com.pt.service;

import com.pt.entity.TorrentMeta;
import com.pt.repository.TorrentMetaRepository;
import com.pt.utils.BencodeCodec;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.security.MessageDigest;
import java.time.LocalDateTime;
import java.util.List;
import java.util.Map;

@Service
public class TorrentService {

    @Autowired
    private TorrentMetaRepository torrentMetaRepository;

    public TorrentMeta parseAndSaveTorrent(byte[] torrentBytes) throws Exception {
        Map<String, Object> torrentDict = (Map<String, Object>) BencodeCodec.decode(torrentBytes);
        if (!torrentDict.containsKey("info")) {
            throw new IllegalArgumentException("Invalid torrent file: missing 'info' dictionary");
        }

        Map<String, Object> infoDict = (Map<String, Object>) torrentDict.get("info");

        // 计算 info_hash
        byte[] infoEncoded = BencodeCodec.encode(infoDict);
        MessageDigest sha1 = MessageDigest.getInstance("SHA-1");
        byte[] infoHashBytes = sha1.digest(infoEncoded);
        String infoHash = bytesToHex(infoHashBytes);

        // 获取文件名，大小等
        String name = (String) infoDict.get("name");
        long length = 0;
        if (infoDict.containsKey("length")) {
            length = ((Number) infoDict.get("length")).longValue();
        } else if (infoDict.containsKey("files")) {
            long totalLength = 0;
            List<Map<String, Object>> files = (List<Map<String, Object>>) infoDict.get("files");
            for (Map<String, Object> file : files) {
                totalLength += ((Number) file.get("length")).longValue();
            }
            length = totalLength;
        }

        // 保存到数据库
        TorrentMeta meta = new TorrentMeta();
        meta.setFilename(name);
        meta.setInfoHash(infoHash);
        meta.setSize(length);
        meta.setUploadTime(LocalDateTime.now());
        meta.setTorrentData(torrentBytes);

        torrentMetaRepository.save(meta);
        return meta;
    }


    private String bytesToHex(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            sb.append(String.format("%02x", b));
        }
        return sb.toString();
    }
}