const { spawn, exec, execFile } = require('child_process');
const path = require('path');
const fs = require('fs');
const { resolveRuntimeStrategy } = require('./path-utils');

/**
 * MySQL 进程管理器
 * 使用进程模式启动 MySQL，无需管理员权限
 */
class MySQLProcessManager {
  constructor(logWindowManager = null) {
    const isDev = !process.resourcesPath;
    const baseDir = isDev
      ? path.join(__dirname, '..')
      : path.dirname(process.resourcesPath);
    const pathStrategy = resolveRuntimeStrategy(baseDir);

    this.baseDir = baseDir;
    this.pathStrategy = pathStrategy;
    this.sourceMysqlPath = path.join(baseDir, 'mysql');
    this.mysqlPath = pathStrategy.usesSafePaths
      ? path.join(pathStrategy.safeRuntimeRoot, 'mysql')
      : this.sourceMysqlPath;
    this.binPath = path.join(this.mysqlPath, 'bin');
    this.dataPath = path.join(this.mysqlPath, 'data');
    this.configFile = path.join(this.mysqlPath, 'my.ini');
    this.processRecordFile = path.join(this.mysqlPath, '.running-process.json');
    this.logWindowManager = logWindowManager;

    // 进程模式：保存 MySQL 进程引用
    this.mysqlProcess = null;
    this.currentPort = null;
  }

  // 睡眠函数
  sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
  }

  // 日志输出辅助方法
  log(type, message) {
    console.log(`[MySQL] ${message}`);
    if (this.logWindowManager) {
      this.logWindowManager.addLog(type, `[MySQL] ${message}`);
    }
  }

  normalizeComparablePath(target = '') {
    return String(target).replace(/"/g, '').replace(/\//g, '\\').toLowerCase();
  }

  saveProcessRecord(record = {}) {
    try {
      fs.mkdirSync(path.dirname(this.processRecordFile), { recursive: true });
      fs.writeFileSync(this.processRecordFile, JSON.stringify(record, null, 2), 'utf-8');
    } catch (error) {
      this.log('warn', `写入 MySQL 进程标记失败: ${error.message}`);
    }
  }

  getProcessRecord() {
    try {
      if (!fs.existsSync(this.processRecordFile)) {
        return null;
      }

      return JSON.parse(fs.readFileSync(this.processRecordFile, 'utf-8'));
    } catch (error) {
      this.log('warn', `读取 MySQL 进程标记失败: ${error.message}`);
      return null;
    }
  }

  clearProcessRecord() {
    try {
      if (fs.existsSync(this.processRecordFile)) {
        fs.unlinkSync(this.processRecordFile);
      }
    } catch (error) {
      this.log('warn', `清理 MySQL 进程标记失败: ${error.message}`);
    }
  }

  execFileCommand(command, args = []) {
    return new Promise((resolve, reject) => {
      execFile(command, args, { encoding: 'utf8', windowsHide: true }, (error, stdout, stderr) => {
        if (error) {
          const err = new Error(error.message || stderr || stdout || 'Command execution failed');
          err.code = error.code;
          err.stdout = stdout;
          err.stderr = stderr;
          reject(err);
        } else {
          resolve({ stdout, stderr });
        }
      });
    });
  }

  async getProcessInfoByPid(pid) {
    if (!pid) {
      return null;
    }

    try {
      const script = `$proc = Get-CimInstance Win32_Process -Filter "ProcessId = ${pid}"; if ($proc) { [PSCustomObject]@{ executablePath = $proc.ExecutablePath; commandLine = $proc.CommandLine; name = $proc.Name } | ConvertTo-Json -Compress }`;
      const { stdout } = await this.execFileCommand('powershell.exe', ['-NoProfile', '-Command', script]);
      const raw = (stdout || '').trim();
      return raw ? JSON.parse(raw) : null;
    } catch (error) {
      return null;
    }
  }

  async isOwnMySQLProcess(pid, record = this.getProcessRecord()) {
    const processInfo = await this.getProcessInfoByPid(pid);
    if (!processInfo) {
      return false;
    }

    const expectedExe = this.normalizeComparablePath(path.join(this.binPath, 'mysqld.exe'));
    const expectedConfig = this.normalizeComparablePath((record && record.configFile) || this.configFile);
    const executablePath = this.normalizeComparablePath(processInfo.executablePath);
    const commandLine = this.normalizeComparablePath(processInfo.commandLine);

    if (executablePath !== expectedExe) {
      return false;
    }

    // 关键校验：仅在命令行绑定到当前应用自己的 my.ini 时才允许清理。
    return !expectedConfig || commandLine.includes(`--defaults-file=${expectedConfig}`) || commandLine.includes(expectedConfig);
  }

  async waitForProcessExit(pid, timeoutMs = 3000) {
    const deadline = Date.now() + timeoutMs;

    while (Date.now() < deadline) {
      const processInfo = await this.getProcessInfoByPid(pid);
      if (!processInfo) {
        return true;
      }
      await this.sleep(200);
    }

    return false;
  }

  async terminateTrackedProcess(record = this.getProcessRecord(), reason = '正在停止 MySQL 进程...') {
    const pid = this.mysqlProcess?.pid || record?.pid;
    const port = this.currentPort || record?.port || this.readPortFromConfig();

    if (!pid) {
      this.log('system', '未找到可清理的 MySQL 进程标记');
      this.clearProcessRecord();
      return false;
    }

    const isOwnProcess = await this.isOwnMySQLProcess(pid, record);
    if (!isOwnProcess) {
      this.log('warn', `PID ${pid} 不是当前应用的 MySQL 进程，跳过清理`);
      this.clearProcessRecord();
      if (this.mysqlProcess && this.mysqlProcess.pid === pid) {
        this.mysqlProcess = null;
      }
      return false;
    }

    this.log('system', `${reason} PID=${pid}${port ? `, 端口=${port}` : ''}`);

    // 优先按当前应用自己的端口优雅关闭，避免强杀带来的数据损坏风险。
    if (port) {
      try {
        const mysqladmin = path.join(this.binPath, 'mysqladmin.exe');
        await this.execCommand(`"${mysqladmin}" -u root -P ${port} shutdown`);
        const exited = await this.waitForProcessExit(pid, 5000);
        if (exited) {
          this.log('success', 'MySQL 进程已优雅关闭');
          this.clearProcessRecord();
          if (this.mysqlProcess && this.mysqlProcess.pid === pid) {
            this.mysqlProcess = null;
          }
          this.currentPort = null;
          return true;
        }
      } catch (error) {
        this.log('warn', `优雅关闭失败，准备按 PID 清理: ${error.message}`);
      }
    }

    await this.execCommand(`taskkill /F /T /PID ${pid}`);
    await this.waitForProcessExit(pid, 3000);
    this.log('success', 'MySQL 进程已按 PID 清理');
    this.clearProcessRecord();
    if (this.mysqlProcess && this.mysqlProcess.pid === pid) {
      this.mysqlProcess = null;
    }
    this.currentPort = null;
    return true;
  }

  /**
   * 递归复制目录。
   * 仅当文件不存在、大小变化或源文件时间更新时才覆盖，避免每次启动全量重写。
   */
  copyDirectorySync(sourceDir, targetDir, options = {}) {
    const {
      excludeTopLevelDirs = new Set(),
      excludeFileNames = new Set(),
      excludeFileExtensions = new Set()
    } = options;

    if (!fs.existsSync(sourceDir)) {
      return;
    }

    if (!fs.existsSync(targetDir)) {
      fs.mkdirSync(targetDir, { recursive: true });
    }

    const entries = fs.readdirSync(sourceDir, { withFileTypes: true });

    entries.forEach((entry) => {
      const sourcePath = path.join(sourceDir, entry.name);
      const targetPath = path.join(targetDir, entry.name);
      const isTopLevelEntry = sourceDir === this.sourceMysqlPath;

      if (entry.isDirectory()) {
        if (isTopLevelEntry && excludeTopLevelDirs.has(entry.name)) {
          return;
        }

        this.copyDirectorySync(sourcePath, targetPath, options);
        return;
      }

      const extension = path.extname(entry.name).toLowerCase();
      if (excludeFileNames.has(entry.name) || excludeFileExtensions.has(extension)) {
        return;
      }

      let shouldCopy = !fs.existsSync(targetPath);
      if (!shouldCopy) {
        const sourceStat = fs.statSync(sourcePath);
        const targetStat = fs.statSync(targetPath);
        shouldCopy = sourceStat.size !== targetStat.size || sourceStat.mtimeMs > targetStat.mtimeMs;
      }

      if (shouldCopy) {
        fs.copyFileSync(sourcePath, targetPath);
      }
    });
  }

  /**
   * 非 ASCII 路径下，将 MySQL 运行环境同步到英文安全目录。
   */
  ensureRuntimeEnvironment() {
    if (!this.pathStrategy.usesSafePaths) {
      return;
    }

    this.log('system', '检测到应用路径包含非 ASCII 字符，启用 MySQL 英文安全运行目录');
    this.log('system', `MySQL 源目录: ${this.sourceMysqlPath}`);
    this.log('system', `MySQL 运行目录: ${this.mysqlPath}`);
    this.log('system', `MySQL 数据目录: ${this.dataPath}`);

    fs.mkdirSync(this.mysqlPath, { recursive: true });
    fs.mkdirSync(path.dirname(this.dataPath), { recursive: true });

    this.copyDirectorySync(this.sourceMysqlPath, this.mysqlPath, {
      excludeTopLevelDirs: new Set(['data', 'data_backup']),
      excludeFileNames: new Set(['my.ini', 'mysql_error.log', 'mysql_slow.log']),
      excludeFileExtensions: new Set(['.pid', '.err'])
    });

    this.ensureSeedData();
  }

  /**
   * 首次进入英文安全路径模式时，将打包内预置数据库复制到安全数据目录。
   */
  ensureSeedData() {
    const hasTargetData = fs.existsSync(this.dataPath) && fs.readdirSync(this.dataPath).length > 0;
    if (hasTargetData) {
      this.log('system', '检测到已有 MySQL 安全数据目录，直接复用');
      return;
    }

    const sourceDataPath = path.join(this.sourceMysqlPath, 'data');
    if (fs.existsSync(sourceDataPath) && fs.readdirSync(sourceDataPath).length > 0) {
      this.log('system', '首次启动，正在复制预置 MySQL 数据到安全数据目录...');
      this.copyDirectorySync(sourceDataPath, this.dataPath);
      this.log('success', '预置 MySQL 数据复制完成');
      return;
    }

    fs.mkdirSync(this.dataPath, { recursive: true });
    this.log('warn', '未找到预置 MySQL 数据目录，后续将按空库初始化');
  }

  /**
   * 执行命令并返回Promise
   */
  execCommand(command) {
    return new Promise((resolve, reject) => {
      exec(command, { encoding: 'utf8' }, (error, stdout, stderr) => {
        if (error) {
          const err = new Error(error.message || stderr || stdout || 'Command execution failed');
          err.code = error.code;
          err.stdout = stdout;
          err.stderr = stderr;
          reject(err);
        } else {
          resolve({ stdout, stderr });
        }
      });
    });
  }

  /**
   * 读取配置文件中的端口
   */
  readPortFromConfig() {
    try {
      if (fs.existsSync(this.configFile)) {
        const content = fs.readFileSync(this.configFile, 'utf-8');
        const match = content.match(/port\s*=\s*(\d+)/);
        return match ? parseInt(match[1]) : 3306;
      }
    } catch (error) {
      console.error('[MySQL] Failed to read port from config:', error);
    }
    return 3306;
  }

  /**
   * 生成 my.ini 配置文件
   */
  generateMyIni(port) {
    const basedir = this.mysqlPath.replace(/\\/g, '/');
    const datadir = this.dataPath.replace(/\\/g, '/');

    const config = `[mysqld]
# 基础路径配置
basedir=${basedir}
datadir=${datadir}

# 网络配置
port=${port}
bind-address=0.0.0.0

# 字符集配置
character-set-server=utf8mb4
collation-server=utf8mb4_unicode_ci

# 性能优化
max_connections=200
innodb_buffer_pool_size=128M
innodb_log_file_size=64M

# 日志配置
log_error=${basedir}/mysql_error.log
slow_query_log=1
slow_query_log_file=${basedir}/mysql_slow.log
long_query_time=2

# 安全配置
sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION

[client]
default-character-set=utf8mb4
`;

    fs.writeFileSync(this.configFile, config, 'utf-8');
    this.log('system', `生成配置文件，端口: ${port}`);
  }

  /**
   * 初始化数据库
   */
  async initializeDatabase() {
    return new Promise((resolve, reject) => {
      this.log('system', '正在初始化 MySQL 数据库...');

      const mysqld = path.join(this.binPath, 'mysqld.exe');
      const initProcess = spawn(mysqld, [
        '--defaults-file=' + this.configFile,
        '--initialize-insecure'
      ], {
        cwd: this.mysqlPath,
        stdio: 'pipe'
      });

      initProcess.stdout.on('data', (data) => {
        this.log('system', data.toString().trim());
      });

      initProcess.stderr.on('data', (data) => {
        this.log('system', data.toString().trim());
      });

      initProcess.on('close', (code) => {
        if (code === 0) {
          this.log('success', '数据库初始化成功');
          resolve();
        } else {
          reject(new Error(`数据库初始化失败，退出码: ${code}`));
        }
      });

      initProcess.on('error', (err) => {
        reject(err);
      });
    });
  }

  /**
   * 检查数据库是否已初始化
   */
  isDatabaseInitialized() {
    return fs.existsSync(this.dataPath) && fs.readdirSync(this.dataPath).length > 0;
  }

  /**
   * 检查是否有残留的 mysqld 进程
   */
  async checkAndKillOrphanProcess() {
    const record = this.getProcessRecord();
    if (!record || !record.pid) {
      return;
    }

    const isOwnProcess = await this.isOwnMySQLProcess(record.pid, record);
    if (!isOwnProcess) {
      this.log('warn', `检测到失效的 MySQL 进程标记 PID=${record.pid}，已跳过清理并移除标记`);
      this.clearProcessRecord();
      return;
    }

    this.log('warn', `检测到当前应用上次遗留的 MySQL 进程 PID=${record.pid}，开始定向清理...`);
    await this.terminateTrackedProcess(record, '正在清理当前应用遗留的 MySQL 进程...');
  }

  /**
   * 进程模式：启动 MySQL 进程
   */
  async startMySQLProcess(port) {
    return new Promise((resolve, reject) => {
      const mysqld = path.join(this.binPath, 'mysqld.exe');

      this.log('system', '正在启动 MySQL 进程...');
      this.log('system', `可执行文件: ${mysqld}`);
      this.log('system', `配置文件: ${this.configFile}`);

      // 检查文件是否存在
      if (!fs.existsSync(mysqld)) {
        return reject(new Error(`mysqld.exe 不存在: ${mysqld}`));
      }
      if (!fs.existsSync(this.configFile)) {
        return reject(new Error(`配置文件不存在: ${this.configFile}`));
      }

      const mysqlProcess = spawn(mysqld, [
        `--defaults-file=${this.configFile}`,
        '--console'
      ], {
        cwd: this.mysqlPath,
        stdio: ['ignore', 'pipe', 'pipe'],
        windowsHide: true
      });
      this.mysqlProcess = mysqlProcess;
      this.currentPort = port;

      this.saveProcessRecord({
        pid: mysqlProcess.pid,
        port,
        executablePath: mysqld,
        configFile: this.configFile,
        mysqlPath: this.mysqlPath,
        createdAt: new Date().toISOString()
      });

      let startupComplete = false;
      let startupTimeout = null;

      // 监听 stderr（MySQL 主要输出在 stderr）
      mysqlProcess.stderr.on('data', (data) => {
        const msg = data.toString().trim();
        if (msg) {
          // 检查启动成功标志
          if (msg.includes('ready for connections') || msg.includes('port:')) {
            if (!startupComplete) {
              startupComplete = true;
              if (startupTimeout) clearTimeout(startupTimeout);
              this.log('success', 'MySQL 进程已就绪');
              resolve(true);
            }
          }

          // 输出日志（过滤一些不重要的信息）
          if (!msg.includes('[Note]') || msg.includes('error') || msg.includes('ready')) {
            this.log('system', `[mysqld] ${msg}`);
          }
        }
      });

      mysqlProcess.stdout.on('data', (data) => {
        const msg = data.toString().trim();
        if (msg) {
          this.log('system', `[mysqld] ${msg}`);
        }
      });

      mysqlProcess.on('error', (err) => {
        this.log('error', `MySQL 进程启动失败: ${err.message}`);
        this.clearProcessRecord();
        this.mysqlProcess = null;
        reject(err);
      });

      mysqlProcess.on('exit', (code, signal) => {
        this.log('system', `MySQL 进程退出，代码: ${code}, 信号: ${signal}`);
        const record = this.getProcessRecord();
        if (record && record.pid === mysqlProcess.pid) {
          this.clearProcessRecord();
        }
        this.mysqlProcess = null;
        this.currentPort = null;

        // 如果还没完成启动就退出了，说明启动失败
        if (!startupComplete) {
          reject(new Error(`MySQL 进程异常退出，代码: ${code}`));
        }
      });

      // 超时处理（30秒）
      startupTimeout = setTimeout(() => {
        if (!startupComplete && mysqlProcess) {
          // 进程还在运行，认为启动成功
          startupComplete = true;
          this.log('success', 'MySQL 进程启动完成（超时检测）');
          resolve(true);
        }
      }, 30000);
    });
  }

  /**
   * 进程模式：停止 MySQL 进程
   */
  async stopMySQLProcess() {
    const record = this.getProcessRecord();
    if (!this.mysqlProcess && !record) {
      this.log('system', 'MySQL 进程未运行');
      return;
    }

    await this.terminateTrackedProcess(record, '正在停止当前应用自己的 MySQL 进程...');
  }

  /**
   * 检查 MySQL 进程是否在运行
   */
  isMySQLRunning() {
    return this.mysqlProcess !== null && !this.mysqlProcess.killed;
  }

  /**
   * 主流程：确保 MySQL 运行（进程模式）
   * @param {function} findAvailablePort - 查找可用端口的函数
   * @param {function} waitForPort - 等待端口就绪的函数
   * @returns {Promise<number>} 返回 MySQL 运行的端口
   */
  async ensureServiceRunning(findAvailablePort, waitForPort) {
    this.ensureRuntimeEnvironment();

    this.log('system', '开始 MySQL 进程检查流程（进程模式）');
    this.log('system', `路径策略: ${this.pathStrategy.usesSafePaths ? '英文安全路径模式' : '应用目录直启模式'}`);
    this.log('system', `MySQL 路径: ${this.mysqlPath}`);
    this.log('system', `配置文件: ${this.configFile}`);

    // 1. 检查是否已有 MySQL 进程在运行
    if (this.isMySQLRunning()) {
      const port = this.currentPort || this.readPortFromConfig();
      this.log('success', `MySQL 进程已在运行，端口: ${port}`);
      return port;
    }

    // 2. 检查并清理残留进程
    await this.checkAndKillOrphanProcess();

    // 3. 查找可用端口
    const port = await findAvailablePort(3306, 100);
    this.log('system', `找到可用端口: ${port}`);

    // 4. 检查数据库是否已初始化
    if (!this.isDatabaseInitialized()) {
      this.log('system', '数据库未初始化，开始初始化...');
      this.generateMyIni(port);
      await this.initializeDatabase();
    } else {
      this.log('system', '检测到已有数据库目录');
      // 更新配置文件（可能端口变了）
      this.generateMyIni(port);
    }

    // 5. 启动 MySQL 进程
    this.log('system', '启动 MySQL 进程...');
    await this.startMySQLProcess(port);

    // 6. 等待端口就绪
    const finalPort = this.readPortFromConfig();
    this.currentPort = finalPort;

    this.log('system', `等待端口 ${finalPort} 就绪...`);
    const portReady = await waitForPort(finalPort, 30000);

    if (!portReady) {
      throw new Error(`MySQL 端口 ${finalPort} 未能在 30 秒内就绪`);
    }

    this.log('success', `MySQL 进程启动成功，端口: ${finalPort}`);
    return finalPort;
  }
}

module.exports = MySQLProcessManager;