txtdot/src/errors/handler.ts

import { FastifyReply, FastifyRequest } from 'fastify';
import { NotHtmlMimetypeError } from './main';
import { getFastifyError } from './validation';

import { TxtDotError } from '@txtdot/sdk/dist/types/errors';

import { IGetSchema } from '../types/requests/browser';
import getConfig from '../config/main';

export default function errorHandler(
  error: Error,
  req: FastifyRequest,
  reply: FastifyReply
) {
  if (req.originalUrl.startsWith('/api/')) {
    return apiErrorHandler(error, reply);
  }

  const url = (req as FastifyRequest<IGetSchema>).query.url;
  return htmlErrorHandler(error, reply, url);
}

function apiErrorHandler(error: Error, reply: FastifyReply) {
  function generateResponse(code: number) {
    return reply.code(code).send({
      data: null,
      error: {
        code: code,
        name: error.name,
        message: error.message,
      },
    });
  }

  if (getFastifyError(error)?.statusCode === 400) {
    return generateResponse(400);
  }

  if (error instanceof TxtDotError) {
    return generateResponse(error.code);
  }

  return generateResponse(500);
}

function htmlErrorHandler(error: Error, reply: FastifyReply, url: string) {
  if (getFastifyError(error)?.statusCode === 400) {
    return reply.code(400).view('/templates/error.ejs', {
      url,
      code: 400,
      description: `Invalid parameter specified: ${error.message}`,
    });
  }

  if (error instanceof TxtDotError) {
    return reply.code(error.code).view('/templates/error.ejs', {
      url,
      code: error.code,
      description: error.description,
      proxyBtn:
        error instanceof NotHtmlMimetypeError && getConfig().proxy.enabled,
    });
  }

  return reply.code(500).view('/templates/error.ejs', {
    url,
    code: 500,
    description: `${error.name}: ${error.message}`,
  });
}