import { NestFactory } from '@nestjs/core';
import { ExpressAdapter } from '@nestjs/platform-express';
import serverlessExpress from '@vendia/serverless-express';
import { ValidationPipe, VersioningType } from '@nestjs/common';
import { Context, Handler } from 'aws-lambda';
import express from 'express';

import { AppModule } from './app.module';

let cachedServer: Handler;

async function bootstrap() {
  if (!cachedServer) {
    const expressApp = express();
    const app = await NestFactory.create(
      AppModule,
      new ExpressAdapter(expressApp),
    );
    app.enableCors();
    app.enableVersioning({
      type: VersioningType.HEADER,
      header: 'Accept-Version',
      defaultVersion: '1',
    });
    app.useGlobalPipes(
      new ValidationPipe({
        transform: true,
        transformOptions: { enableImplicitConversion: true },
      }),
    );
    await app.init();

    cachedServer = serverlessExpress({ app: expressApp });
  }

  return cachedServer;
}

export const handler = async (event: any, context: Context, callback: any) => {
  const server = await bootstrap();
  return server(event, context, callback);
};