package com.mokee.admin.service.impl;

import cn.hutool.crypto.digest.MD5;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.mokee.admin.mapper.SysFileMapper;
import com.mokee.admin.service.ConfigService;
import com.mokee.admin.service.FileService;
import com.mokee.common.entity.SysFile;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.List;

/**
 * 文件服务实现 — 文件二进制数据存储于本地磁盘
 * <p>
 * 磁盘路径结构：{basePath}/{yyyy-MM}/{storageFileName}
 * 例：/data/mokee/gw/file/2026-06/a1b2c3d4e5f6.png
 * <p>
 * 向下兼容：存量 BLOB 数据（file_data 不为空）仍可正常读取。
 *
 * @author mokee
 */
@Slf4j
@Service
@RequiredArgsConstructor
public class FileServiceImpl implements FileService {

    private final SysFileMapper sysFileMapper;
    private final ConfigService configService;

    private static final DateTimeFormatter YYYY_MM = DateTimeFormatter.ofPattern("yyyy-MM");
    private static final String DEFAULT_BASE_PATH = "/data/mokee/gw/file";

    /** 获取配置的存储根目录 */
    private String getBasePath() {
        return configService.getValue("file.storage.disk.path", DEFAULT_BASE_PATH);
    }

    /**
     * 从原始文件名提取扩展名
     */
    private String ext(String fileName) {
        if (fileName == null) return "";
        int i = fileName.lastIndexOf('.');
        return i > 0 ? fileName.substring(i) : "";
    }

    @Override
    public SysFile upload(MultipartFile file, String fileType, String systemId,
                          String userId, String uploadUserName) throws IOException {
        byte[] data = file.getBytes();

        // 计算 MD5
        String md5 = MD5.create().digestHex(data);

        // 构建实体（先生成 ID 用于存储文件名）
        String fileId = cn.hutool.core.lang.UUID.randomUUID().toString().replace("-", "");
        String storageFileName = fileId + ext(file.getOriginalFilename());
        LocalDateTime now = LocalDateTime.now();

        SysFile sf = SysFile.builder()
                .id(fileId)
                .systemId(systemId)
                .fileName(file.getOriginalFilename())
                .storageFileName(storageFileName)
                .fileType(fileType != null ? fileType : "other")
                .fileSize(file.getSize())
                .mimeType(file.getContentType())
                .md5(md5)
                .uploadUserId(userId)
                .uploadUserName(uploadUserName)
                .fileData(null)  // 新文件不写入 BLOB
                .createdAt(now)
                .build();

        // 写入磁盘
        String basePath = getBasePath();
        Path dir = Paths.get(basePath, now.format(YYYY_MM));
        try {
            Files.createDirectories(dir);
        } catch (IOException e) {
            log.error("创建存储目录失败: {} — 请检查磁盘权限和路径配置", dir);
            throw new IOException("存储目录创建失败: " + dir + " (请检查磁盘权限和路径配置)", e);
        }
        Path filePath = dir.resolve(storageFileName);
        try {
            Files.write(filePath, data);
        } catch (IOException e) {
            log.error("写入文件失败: {} — 可能磁盘空间不足或权限不足", filePath);
            throw new IOException("文件写入失败: " + filePath + " (可能磁盘空间不足或权限不足)", e);
        }

        log.info("文件已写入磁盘: {} ({} bytes, md5={})", filePath, file.getSize(), md5);

        // 存元信息到 DB
        sysFileMapper.insert(sf);

        return sf;
    }

    @Override
    public IPage<SysFile> page(Integer page, Integer size, String fileType,
                               String fileName, String uploadUserName, String systemId) {
        LambdaQueryWrapper<SysFile> w = new LambdaQueryWrapper<>();
        if (fileType != null && !fileType.isEmpty()) w.eq(SysFile::getFileType, fileType);
        if (fileName != null && !fileName.isEmpty()) w.like(SysFile::getFileName, fileName);
        if (uploadUserName != null && !uploadUserName.isEmpty()) w.like(SysFile::getUploadUserName, uploadUserName);
        if (systemId != null) w.eq(SysFile::getSystemId, systemId);
        w.orderByDesc(SysFile::getCreatedAt);
        w.select(SysFile.class, f -> !"file_data".equals(f.getColumn()));
        return sysFileMapper.selectPage(new Page<>(page, size), w);
    }

    @Override
    public List<SysFile> list(String fileType, String systemId) {
        LambdaQueryWrapper<SysFile> w = new LambdaQueryWrapper<>();
        if (fileType != null && !fileType.isEmpty()) w.eq(SysFile::getFileType, fileType);
        if (systemId != null) w.eq(SysFile::getSystemId, systemId);
        w.orderByDesc(SysFile::getCreatedAt);
        w.select(SysFile.class, f -> !"file_data".equals(f.getColumn()));
        return sysFileMapper.selectList(w);
    }

    @Override
    public SysFile getById(String id) {
        return sysFileMapper.selectById(id);
    }

    @Override
    public SysFile getMetaById(String id) {
        LambdaQueryWrapper<SysFile> w = new LambdaQueryWrapper<>();
        w.eq(SysFile::getId, id);
        w.select(SysFile.class, f -> !"file_data".equals(f.getColumn()));
        return sysFileMapper.selectOne(w);
    }

    @Override
    public Path getDiskPath(SysFile sf) {
        String basePath = getBasePath();
        // 存量兼容：旧文件 storageFileName 为空时，用 id + 扩展名兜底
        String storageName = sf.getStorageFileName();
        if (storageName == null || storageName.isEmpty()) {
            storageName = sf.getId() + ext(sf.getFileName());
        }
        return Paths.get(basePath, sf.getCreatedAt().format(YYYY_MM), storageName);
    }

    @Override
    public void delete(String id) throws IOException {
        SysFile sf = sysFileMapper.selectById(id);
        if (sf == null) return;

        // 删除磁盘文件（失败不阻断 DB 删除）
        try {
            Path path = getDiskPath(sf);
            if (Files.exists(path)) {
                Files.delete(path);
                log.info("磁盘文件已删除: {}", path);
            }
        } catch (Exception e) {
            log.warn("删除磁盘文件失败（继续删DB记录） - id: {}, error: {}", id, e.getMessage());
        }

        // 删除 DB 记录
        sysFileMapper.deleteById(id);
    }
}