package cn.iocoder.yudao.module.system.service.database;

import cn.hutool.core.date.DateUtil;
import cn.hutool.core.io.FileUtil;
import cn.hutool.core.io.IoUtil;
import cn.hutool.core.util.StrUtil;
import cn.iocoder.yudao.framework.common.exception.ServiceException;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

@Service
@Slf4j
public class DatabaseBackupServiceImpl implements DatabaseBackupService {

    /** 备份超时时间（分钟） */
    private static final long BACKUP_TIMEOUT_MINUTES = 10;
    /** MySQL 容器内部端口 */
    private static final String DOCKER_MYSQL_PORT = "3306";

    @Value("${spring.datasource.dynamic.datasource.master.url:}")
    private String dbUrl;

    @Value("${spring.datasource.dynamic.datasource.master.username:root}")
    private String dbUsername;

    @Value("${spring.datasource.dynamic.datasource.master.password:}")
    private String dbPassword;

    /** 备份命令，可显式指定（如 docker exec mysql8 mysqldump）；留空则自动检测本地 mysqldump 或 Docker MySQL 容器 */
    @Value("${yudao.database-backup.command:}")
    private String backupCommand;

    /** 备份目标数据库 host，留空则从数据源 JDBC URL 解析 */
    @Value("${yudao.database-backup.host:}")
    private String backupHost;

    /** 备份目标数据库 port，留空则从数据源 JDBC URL 解析 */
    @Value("${yudao.database-backup.port:}")
    private String backupPort;

    /** 备份目标数据库名，留空则从数据源 JDBC URL 解析 */
    @Value("${yudao.database-backup.database:}")
    private String backupDatabase;

    /** 备份账号，留空则使用数据源账号 */
    @Value("${yudao.database-backup.username:}")
    private String backupUsername;

    /** 备份密码，留空则使用数据源密码 */
    @Value("${yudao.database-backup.password:}")
    private String backupPassword;

    @Override
    public void backupDatabase(HttpServletResponse response) throws Exception {
        if (StrUtil.isEmpty(dbUrl)) {
            throw new ServiceException(500, "未找到数据库连接配置");
        }

        // 备份连接的数据库信息：优先使用 yudao.database-backup 配置，未配置的部分从数据源 JDBC URL 解析兜底
        String dbHost = backupHost;
        String dbPort = backupPort;
        String dbName = backupDatabase;
        if (StrUtil.isEmpty(dbHost) || StrUtil.isEmpty(dbPort) || StrUtil.isEmpty(dbName)) {
            Matcher matcher = Pattern.compile("jdbc:mysql://([^:]+):(\\d+)/([^?]+)").matcher(dbUrl);
            if (matcher.find()) {
                if (StrUtil.isEmpty(dbHost)) {
                    dbHost = matcher.group(1);
                }
                if (StrUtil.isEmpty(dbPort)) {
                    dbPort = matcher.group(2);
                }
                if (StrUtil.isEmpty(dbName)) {
                    dbName = matcher.group(3);
                }
            }
        }
        if (StrUtil.isEmpty(dbHost) || StrUtil.isEmpty(dbPort) || StrUtil.isEmpty(dbName)) {
            log.warn("无法从配置或 JDBC URL 解析完整的数据库信息: host={}, port={}, db={}", dbHost, dbPort, dbName);
            throw new ServiceException(500, "无法解析数据库备份连接信息，请在 yudao.database-backup 中配置 host/port/database");
        }
        String username = StrUtil.isEmpty(backupUsername) ? dbUsername : backupUsername;
        String password = StrUtil.isEmpty(backupPassword) ? dbPassword : backupPassword;

        // 检测部署环境，构建备份命令
        List<String> commandParts = new ArrayList<>();
        String connectHost = dbHost;
        String connectPort = dbPort;
        if (StrUtil.isNotEmpty(backupCommand)) {
            // 手动指定命令，优先使用
            for (String token : backupCommand.trim().split("\\s+")) {
                commandParts.add(token);
            }
            log.info("使用手动配置的备份命令: {}", backupCommand);
        } else if (isLocalMysqldumpAvailable()) {
            // 本地部署：本机已安装 mysqldump
            commandParts.add("mysqldump");
            log.info("检测到本机 mysqldump，使用本地备份命令");
        } else {
            // Docker 部署：查找运行中的 MySQL 容器，通过 docker exec 调用容器内 mysqldump
            String container = findMysqlDockerContainer(dbPort);
            if (StrUtil.isEmpty(container)) {
                throw new ServiceException(500, "未检测到可用的 mysqldump 环境：本机未安装 MySQL 客户端，"
                        + "也未发现运行中的 MySQL Docker 容器。可通过配置 yudao.database-backup.command 手动指定备份命令");
            }
            commandParts.add("docker");
            commandParts.add("exec");
            // docker exec 不会转发宿主机环境变量，密码需通过 -e 显式传入容器
            if (StrUtil.isNotEmpty(password)) {
                commandParts.add("-e");
                commandParts.add("MYSQL_PWD=" + password);
            }
            commandParts.add(container);
            commandParts.add("mysqldump");
            // 容器内固定使用 127.0.0.1:3306 走 TCP 连接自身，绕开 socket 认证差异
            connectHost = "127.0.0.1";
            connectPort = DOCKER_MYSQL_PORT;
            log.info("检测到 Docker 部署，使用容器 [{}] 执行 mysqldump", container);
        }
        commandParts.add("-h" + connectHost);
        commandParts.add("-P" + connectPort);
        commandParts.add("-u" + username);
        if (StrUtil.isEmpty(password)) {
            commandParts.add("--skip-password");
        }
        commandParts.add(dbName);

        String timestamp = DateUtil.format(new Date(), "yyyyMMdd_HHmmss");
        String fileName = "backup_" + timestamp + ".sql";
        File tempFile = File.createTempFile("backup_", ".sql");

        try {
            ProcessBuilder pb = new ProcessBuilder(commandParts);
            // 数据库密码通过环境变量传递，避免出现在命令行及进程列表
            if (StrUtil.isNotEmpty(password)) {
                pb.environment().put("MYSQL_PWD", password);
            }
            Process process = pb.start();

            // 后台读取 stderr，防止管道缓冲区写满导致进程阻塞
            StringBuilder stderr = new StringBuilder();
            Thread stderrThread = new Thread(() -> {
                try (BufferedReader reader = new BufferedReader(
                        new InputStreamReader(process.getErrorStream(), StandardCharsets.UTF_8))) {
                    String line;
                    while ((line = reader.readLine()) != null) {
                        stderr.append(line).append(System.lineSeparator());
                    }
                } catch (IOException ignored) {
                }
            });
            stderrThread.start();

            // stdout 写入本地临时文件（docker exec 场景输出不会落在容器内文件系统）
            try (InputStream in = process.getInputStream();
                 OutputStream out = new FileOutputStream(tempFile)) {
                IoUtil.copy(in, out);
            }

            boolean finished = process.waitFor(BACKUP_TIMEOUT_MINUTES, TimeUnit.MINUTES);
            stderrThread.join();
            if (!finished) {
                process.destroyForcibly();
                throw new ServiceException(500, "数据库备份超时（超过 " + BACKUP_TIMEOUT_MINUTES + " 分钟）");
            }
            if (process.exitValue() != 0) {
                log.error("数据库备份失败, exitCode: {}, error: {}", process.exitValue(), stderr);
                throw new ServiceException(500, "数据库备份失败: " + stderr);
            }

            // 设置响应头
            response.setContentType("application/octet-stream; charset=UTF-8");
            response.setHeader("Content-Disposition", "attachment; filename=\"" + URLEncoder.encode(fileName, "UTF-8") + "\"");
            response.setContentLengthLong(tempFile.length());

            // 写入响应流
            try (FileInputStream fis = new FileInputStream(tempFile);
                 OutputStream os = response.getOutputStream()) {
                IoUtil.copy(fis, os);
            }
        } finally {
            // 删除临时文件
            FileUtil.del(tempFile);
        }
    }

    /**
     * 检测本机 mysqldump 是否可用
     */
    private boolean isLocalMysqldumpAvailable() {
        try {
            Process process = new ProcessBuilder("mysqldump", "--version").redirectErrorStream(true).start();
            boolean finished = process.waitFor(5, TimeUnit.SECONDS);
            if (!finished) {
                process.destroyForcibly();
                return false;
            }
            return process.exitValue() == 0;
        } catch (IOException e) {
            return false;
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            return false;
        }
    }

    /**
     * 查找运行中的 MySQL Docker 容器，优先选择端口映射与数据源端口一致的容器
     *
     * @return 容器名；未找到返回 null
     */
    private String findMysqlDockerContainer(String dbPort) {
        try {
            Process ps = new ProcessBuilder("docker", "ps", "--format", "{{.ID}}|{{.Names}}|{{.Image}}")
                    .redirectErrorStream(true).start();
            String output = IoUtil.read(ps.getInputStream(), StandardCharsets.UTF_8);
            if (!ps.waitFor(10, TimeUnit.SECONDS) || ps.exitValue() != 0) {
                return null;
            }
            List<String[]> containers = new ArrayList<>();
            for (String line : output.split("\n")) {
                String[] parts = line.trim().split("\\|");
                if (parts.length == 3 && parts[2].startsWith("mysql")) {
                    containers.add(parts);
                }
            }
            if (containers.isEmpty()) {
                return null;
            }
            // 优先选择端口映射与数据源端口一致的容器
            for (String[] container : containers) {
                Process portProcess = new ProcessBuilder("docker", "port", container[0], "3306/tcp")
                        .redirectErrorStream(true).start();
                String portOutput = IoUtil.read(portProcess.getInputStream(), StandardCharsets.UTF_8);
                if (portProcess.waitFor(10, TimeUnit.SECONDS) && portProcess.exitValue() == 0
                        && portOutput.contains(dbPort)) {
                    return container[1];
                }
            }
            log.warn("未匹配到端口映射的 MySQL 容器，使用第一个: {}", containers.get(0)[1]);
            return containers.get(0)[1];
        } catch (IOException e) {
            log.warn("检测 Docker 环境失败: {}", e.getMessage());
            return null;
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            return null;
        }
    }
}