import {
  ArgumentsHost,
  Catch,
  ExceptionFilter,
  HttpException,
  HttpStatus,
} from '@nestjs/common';
import { Response } from 'express';

@Catch()
export class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: unknown, host: ArgumentsHost) {
    const ctx = host.switchToHttp();
    const response = ctx.getResponse<Response>();

    const status =
      exception instanceof HttpException
        ? exception.getStatus()
        : HttpStatus.INTERNAL_SERVER_ERROR;

    const body =
      exception instanceof HttpException
        ? exception.getResponse()
        : { message: 'Internal server error' };

    const message =
      typeof body === 'object' && body !== null && 'message' in body
        ? body.message
        : body;

    response.status(status).json({
      success: false,
      data: null,
      error: {
        code: this.resolveCode(status),
        message: Array.isArray(message) ? message.join(', ') : String(message),
      },
    });
  }

  private resolveCode(status: number) {
    if (status === 400) return 'VALIDATION_ERROR';
    if (status === 401) return 'UNAUTHORIZED';
    if (status === 404) return 'NOT_FOUND';
    if (status === 429) return 'RATE_LIMITED';
    if (status === 502) return 'UPSTREAM_ERROR';
    if (status === 503) return 'SERVICE_UNAVAILABLE';
    return 'INTERNAL_ERROR';
  }
}