/**
 * JavaScript/TypeScript 沙箱执行引擎
 * 在隔离的 iframe 中安全执行代码
 */

import type { IExecutionEngine, ExecutionResult } from '../types';

// 执行超时时间（毫秒）
const EXECUTION_TIMEOUT = 10000;

// 最大输出长度
const MAX_OUTPUT_LENGTH = 50000;

export class SandboxEngine implements IExecutionEngine {
  private iframe: HTMLIFrameElement | null = null;
  private abortController: AbortController | null = null;

  supports(language: string): boolean {
    const lang = language.toLowerCase();
    return ['javascript', 'js', 'typescript', 'ts'].includes(lang);
  }

  async execute(code: string, language: string): Promise<ExecutionResult> {
    const startTime = performance.now();
    const lang = language.toLowerCase();

    try {
      // TypeScript 需要先编译
      let executableCode = code;
      if (lang === 'typescript' || lang === 'ts') {
        executableCode = this.transpileTypeScript(code);
      }

      // 在沙箱中执行
      const output = await this.executeInSandbox(executableCode);
      const executionTime = Math.round(performance.now() - startTime);

      return {
        success: true,
        output: output.slice(0, MAX_OUTPUT_LENGTH),
        executionTime,
        engine: 'sandbox',
      };
    } catch (error) {
      const executionTime = Math.round(performance.now() - startTime);
      return {
        success: false,
        output: '',
        error: error instanceof Error ? error.message : String(error),
        executionTime,
        engine: 'sandbox',
      };
    }
  }

  stop(): void {
    if (this.abortController) {
      this.abortController.abort();
    }
    this.cleanup();
  }

  private transpileTypeScript(code: string): string {
    // 简单的 TypeScript 转换（移除类型注解）
    // 实际项目中可以使用 @babel/standalone 或 typescript
    return code
      // 移除类型注解
      .replace(/:\s*\w+(\[\])?(\s*[=,)])/g, '$2')
      // 移除接口定义
      .replace(/interface\s+\w+\s*\{[^}]*\}/g, '')
      // 移除类型别名
      .replace(/type\s+\w+\s*=\s*[^;]+;/g, '')
      // 移除泛型
      .replace(/<[^>]+>/g, '')
      // 移除 as 类型断言
      .replace(/\s+as\s+\w+/g, '')
      // 移除 ! 非空断言
      .replace(/!\./g, '.')
      // 移除可选链前的类型
      .replace(/\?\./g, '?.');
  }

  private executeInSandbox(code: string): Promise<string> {
    return new Promise((resolve, reject) => {
      this.abortController = new AbortController();
      const outputs: string[] = [];

      // 创建隔离的 iframe
      this.iframe = document.createElement('iframe');
      this.iframe.style.display = 'none';
      this.iframe.sandbox.add('allow-scripts');
      document.body.appendChild(this.iframe);

      const iframeWindow = this.iframe.contentWindow;
      if (!iframeWindow) {
        this.cleanup();
        reject(new Error('无法创建执行沙箱'));
        return;
      }

      // 设置超时
      const timeoutId = setTimeout(() => {
        this.cleanup();
        reject(new Error(`执行超时（${EXECUTION_TIMEOUT / 1000}秒）`));
      }, EXECUTION_TIMEOUT);

      // 监听消息
      const messageHandler = (event: MessageEvent) => {
        if (event.source !== iframeWindow) return;

        const { type, data } = event.data;

        if (type === 'console') {
          outputs.push(data);
        } else if (type === 'done') {
          clearTimeout(timeoutId);
          window.removeEventListener('message', messageHandler);
          this.cleanup();
          resolve(outputs.join('\n'));
        } else if (type === 'error') {
          clearTimeout(timeoutId);
          window.removeEventListener('message', messageHandler);
          this.cleanup();
          reject(new Error(data));
        }
      };

      window.addEventListener('message', messageHandler);

      // 中止处理
      this.abortController.signal.addEventListener('abort', () => {
        clearTimeout(timeoutId);
        window.removeEventListener('message', messageHandler);
        this.cleanup();
        reject(new Error('执行已取消'));
      });

      // 在 iframe 中执行代码
      const sandboxCode = `
        (function() {
          const outputs = [];

          // 重写 console 方法
          const originalConsole = console;
          const customConsole = {
            log: (...args) => {
              const msg = args.map(a => {
                if (typeof a === 'object') {
                  try {
                    return JSON.stringify(a, null, 2);
                  } catch {
                    return String(a);
                  }
                }
                return String(a);
              }).join(' ');
              parent.postMessage({ type: 'console', data: msg }, '*');
            },
            error: (...args) => customConsole.log('[Error]', ...args),
            warn: (...args) => customConsole.log('[Warn]', ...args),
            info: (...args) => customConsole.log(...args),
            debug: (...args) => customConsole.log('[Debug]', ...args),
            table: (data) => customConsole.log(JSON.stringify(data, null, 2)),
            clear: () => {},
            dir: (obj) => customConsole.log(obj),
            time: () => {},
            timeEnd: () => {},
            group: () => {},
            groupEnd: () => {},
          };

          // 替换全局 console
          window.console = customConsole;

          // 限制危险 API
          delete window.fetch;
          delete window.XMLHttpRequest;
          delete window.WebSocket;
          delete window.localStorage;
          delete window.sessionStorage;
          delete window.indexedDB;
          delete window.open;
          delete window.close;
          delete window.alert;
          delete window.confirm;
          delete window.prompt;

          try {
            // 执行用户代码
            const result = eval(${JSON.stringify(code)});

            // 如果有返回值且不是 undefined，输出它
            if (result !== undefined) {
              customConsole.log(result);
            }

            parent.postMessage({ type: 'done' }, '*');
          } catch (error) {
            parent.postMessage({ type: 'error', data: error.message || String(error) }, '*');
          }
        })();
      `;

      // 写入并执行
      const iframeDoc = this.iframe.contentDocument;
      if (iframeDoc) {
        iframeDoc.open();
        iframeDoc.write(`<script>${sandboxCode}</script>`);
        iframeDoc.close();
      }
    });
  }

  private cleanup(): void {
    if (this.iframe && this.iframe.parentNode) {
      this.iframe.parentNode.removeChild(this.iframe);
    }
    this.iframe = null;
    this.abortController = null;
  }
}

// 导出单例
export const sandboxEngine = new SandboxEngine();