import { Request, Response, NextFunction } from 'express';
import { MissingMaterialItem } from './models';

export class AppError extends Error {
  public statusCode: number;
  public errorCode: number;

  constructor(message: string, statusCode: number, errorCode: number) {
    super(message);
    this.statusCode = statusCode;
    this.errorCode = errorCode;
    Object.setPrototypeOf(this, AppError.prototype);
  }
}

export class MissingMaterialError extends AppError {
  public missingItems: MissingMaterialItem[];

  constructor(missingItems: MissingMaterialItem[]) {
    super('need_more_material', 400, 4001);
    this.missingItems = missingItems;
    Object.setPrototypeOf(this, MissingMaterialError.prototype);
  }
}

// 请求日志中间件
export const requestLogger = (req: Request, res: Response, next: NextFunction) => {
  const started_at = new Date();
  
  // 拦截 res.send 记录结束时间
  const originalSend = res.send;
  res.send = function (body: any) {
    const ended_at = new Date();
    
    // 提取 case_context
    const case_context = req.body?.case_context || req.body;
    const case_id = case_context?.case_id || 'unknown';
    
    // 提取 meta 数据和 retry_count
    const metadata = case_context?.metadata || {};
    const retry_count = metadata.retry_count || req.headers['x-retry-count'] || req.body?.retry_count || 0;

    // 解析 agent_name
    let agent_name = 'unknown';
    if (req.path.includes('peer-reg-summary')) agent_name = 'AGENT-01';
    else if (req.path.includes('policy-rewrite')) agent_name = 'AGENT-02';
    else if (req.path.includes('compliance-check')) agent_name = 'AGENT-03';
    else if (req.path.includes('legal-pack')) agent_name = 'AGENT-04';
    else if (req.path.includes('log-analysis')) agent_name = 'LOG_ANALYSIS';
    else if (req.path.includes('code-security')) agent_name = 'CODE_SECURITY';
    else if (req.path.includes('regulatory-penalty-summary')) agent_name = 'REG_PENALTY_SUMMARY';

    const status = res.statusCode >= 400 ? 'failed' : 'success';
    const error_code = res.locals.errorCode || 0;
    
    const api_latency_ms = ended_at.getTime() - started_at.getTime();
    const llm_latency_ms = res.locals.llm_latency_ms || 0;

    // 确保绝对不记录 materials，只输出 meta 数据
    console.log(JSON.stringify({
      case_id,
      retry_count,
      agent_name,
      metadata,
      started_at: started_at.toISOString(),
      ended_at: ended_at.toISOString(),
      api_latency_ms,
      llm_latency_ms,
      status,
      error_code
    }));

    return originalSend.call(this, body);
  };

  next();
};

// 全局错误处理中间件
export const errorHandler = (err: any, req: Request, res: Response, next: NextFunction) => {
  let statusCode = 500;
  let errorCode = 5000;
  let message = 'Internal Server Error';
  let extraData: any = null;

  if (err instanceof MissingMaterialError) {
    statusCode = err.statusCode;
    errorCode = err.errorCode;
    message = err.message;
    extraData = { missing_materials: err.missingItems };
  } else if (err instanceof AppError) {
    statusCode = err.statusCode;
    errorCode = err.errorCode;
    message = err.message;
  } else if (err.message === 'LLM_INFERENCE_FAILED') {
    statusCode = 500;
    errorCode = 5001;
    message = '智能体推理失败';
  } else if (err.message === 'MISSING_MATERIALS') {
    statusCode = 400;
    errorCode = 4001;
    message = 'need_more_material';
  } else if (err.message === 'INVALID_FORMAT') {
    statusCode = 400;
    errorCode = 4002;
    message = '输入格式错误';
  } else if (err.message === 'MISSING_CONTEXT') {
    statusCode = 500;
    errorCode = 5002;
    message = '外部上下文缺失';
  } else if (err.message === 'MISSING_LLM_API_KEY') {
    statusCode = 500;
    errorCode = 5003;
    message = 'LLM密钥未配置';
  }

  // 记录 errorCode 给 logger 使用
  res.locals.errorCode = errorCode;

  if (err instanceof MissingMaterialError) {
    res.status(statusCode).json({
      schema_version: 'v1.0',
      error_code: 'need_more_material',
      message: message,
      ...(extraData || {})
    });
  } else {
    res.status(statusCode).json({
      error: {
        code: errorCode,
        message: message,
        ...(extraData || {})
      }
    });
  }
};