package com.webgame.webgamebackend.service.impl;

import com.webgame.webgamebackend.common.auth.AuthenticationProvider;
import com.webgame.webgamebackend.common.dto.user.UpdateStatusRequest;
import com.webgame.webgamebackend.common.dto.user.UpdateUserInfoRequest;
import com.webgame.webgamebackend.common.dto.user.UserInfoResponse;
import com.webgame.webgamebackend.common.exception.BusinessException;
import com.webgame.webgamebackend.common.exception.ErrorCode;
import com.webgame.webgamebackend.entities.UserEntity;
import com.webgame.webgamebackend.repository.UserRepository;
import com.webgame.webgamebackend.service.UserService;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
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.util.Set;

/**
 * 用户服务实现
 */
@Slf4j
@Service
@RequiredArgsConstructor
public class UserServiceImpl implements UserService {

    /** 头像存储目录（相对于项目工作目录） */
    private static final String AVATAR_DIR = "uploads/avatars";

    /**
     * 获取头像存储的绝对路径目录
     *
     * 使用 user.dir 构建绝对路径，避免 Tomcat 临时工作目录导致 FileNotFoundException。
     */
    private Path getAvatarDir() {
        return Paths.get(System.getProperty("user.dir"), AVATAR_DIR).toAbsolutePath();
    }
    /** 允许的头像文件类型 */
    private static final Set<String> ALLOWED_CONTENT_TYPES = Set.of(
            "image/jpeg", "image/png", "image/webp", "image/gif"
    );
    /** 头像文件大小上限（2MB） */
    private static final long MAX_AVATAR_SIZE = 2 * 1024 * 1024;

    private final UserRepository userRepository;
    private final AuthenticationProvider authProvider;

    @Override
    public UserInfoResponse getCurrentUserInfo() {
        String accountId = authProvider.getCurrentUserId();
        log.info("[用户服务] 获取当前登录用户信息, accountId: {}", accountId);
        UserEntity user = userRepository.findByAccountId(accountId)
                .orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));
        return UserInfoResponse.from(user);
    }

    @Override
    @Transactional
    public UserInfoResponse updateUserInfo(String accountId, UpdateUserInfoRequest request) {
        UserEntity user = userRepository.findByAccountId(accountId)
                .orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));

        // 仅更新非 null 字段
        if (request.nickName() != null) {
            user.setNickName(request.nickName());
        }
        if (request.avatar() != null) {
            user.setAvatar(request.avatar());
        }
        if (request.signature() != null) {
            user.setSignature(request.signature());
        }
        if (request.age() != null) {
            user.setAge(request.age());
        }
        if (request.sex() != null) {
            user.setSex(request.sex());
        }
        if (request.birthday() != null) {
            user.setBirthday(request.birthday());
        }

        userRepository.save(user);
        log.info("[用户服务] 更新用户信息, accountId={}", accountId);
        return UserInfoResponse.from(user);
    }

    @Override
    @Transactional
    public void updateStatus(String accountId, UpdateStatusRequest request) {
        UserEntity user = userRepository.findByAccountId(accountId)
                .orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));

        user.setStatus(request.status());
        userRepository.save(user);
        log.info("[用户服务] 更新在线状态, accountId={}, status={}", accountId, request.status());
    }

    @Override
    @Transactional
    public UserInfoResponse uploadAvatar(String accountId, MultipartFile file) {
        // 校验文件类型
        String contentType = file.getContentType();
        if (contentType == null || !ALLOWED_CONTENT_TYPES.contains(contentType)) {
            throw new BusinessException(ErrorCode.AVATAR_INVALID_TYPE);
        }

        // 校验文件大小
        if (file.getSize() > MAX_AVATAR_SIZE) {
            throw new BusinessException(ErrorCode.AVATAR_TOO_LARGE);
        }

        UserEntity user = userRepository.findByAccountId(accountId)
                .orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));

        try {
            // 确保目录存在（使用绝对路径，避免 Tomcat 临时目录问题）
            Path avatarDir = getAvatarDir();
            Files.createDirectories(avatarDir);

            // 删除旧头像文件（如果存在且不是默认 SVG）
            deleteOldAvatarFile(user.getAvatar());

            // 保存新头像：uploads/avatars/{accountId}.jpg
            String filename = accountId + ".jpg";
            Path targetPath = avatarDir.resolve(filename);
            file.transferTo(targetPath.toFile());

            // 更新数据库
            String avatarUrl = "/" + AVATAR_DIR + "/" + filename;
            user.setAvatar(avatarUrl);
            userRepository.save(user);

            log.info("[用户服务] 头像上传成功, accountId={}, path={}", accountId, avatarUrl);
            return UserInfoResponse.from(user);
        } catch (IOException e) {
            log.error("[用户服务] 头像上传失败, accountId={}", accountId, e);
            throw new BusinessException(ErrorCode.AVATAR_UPLOAD_FAILED, "头像保存失败，请重试");
        }
    }

    @Override
    @Transactional
    public UserInfoResponse deleteAvatar(String accountId) {
        UserEntity user = userRepository.findByAccountId(accountId)
                .orElseThrow(() -> new BusinessException(ErrorCode.USER_NOT_FOUND));

        // 删除旧头像文件
        deleteOldAvatarFile(user.getAvatar());

        // 数据库置空（前端会回退显示默认头像）
        user.setAvatar(null);
        userRepository.save(user);

        log.info("[用户服务] 头像已删除, accountId={}", accountId);
        return UserInfoResponse.from(user);
    }

    /**
     * 删除旧的用户头像文件
     *
     * 仅删除 uploads/avatars/ 下的文件，跳过默认 SVG 和非本地路径。
     *
     * @param avatarPath 头像路径，可能为 null
     */
    private void deleteOldAvatarFile(String avatarPath) {
        if (avatarPath == null || !avatarPath.startsWith("/" + AVATAR_DIR + "/")) {
            return;
        }
        try {
            // 从 URL 路径中提取文件名，使用绝对路径删除
            String filename = avatarPath.substring(avatarPath.lastIndexOf('/') + 1);
            Path oldFile = getAvatarDir().resolve(filename);
            Files.deleteIfExists(oldFile);
            log.debug("[用户服务] 旧头像已删除: {}", oldFile);
        } catch (IOException e) {
            log.warn("[用户服务] 旧头像删除失败: {}", avatarPath, e);
        }
    }
}