how to response markdown file using next.js , nest.js

 on nest.js

import {

    Body,

    Controller,

    Get,

    HttpStatus,

    Post,

    Render,

    Req,

    Res,

} from '@nestjs/common';

import { Request, Response } from 'express';

import { Throttle } from '@nestjs/throttler';

import * as fs from 'fs';

import * as path from 'path';

import { AppSessionService } from '../core/app.session.service';

import { AppConstants } from '../core/app.constants';

import { DataMemoryCacher } from '../libs/memory-cacher/data.memory-cacher';

@Controller()

export class AppController {

    constructor(

        private readonly dataCacher: DataMemoryCacher,

        private readonly appSessionService: AppSessionService,

    ) {}

    @Get('/')

    @Render('home')

    app_home(@Req() req: Request, @Res() res: Response): any {

        var hosts = [req.headers.host];

        var username = this.appSessionService.getUserName();

        let last_one = this.dataCacher.get('puu_last_one_from');

        return {

            title: 'PUU - PAAS',

            hosts: hosts,

            username: username,

            last_one: last_one ? last_one.doc_num : '-0-',

        };

    }

    @Get('/about')

    async app_about(@Req() req: Request, @Res() res: Response): Promise<any> {

        let apiDoc = '';

        // // load from cache

        // const keyCache = 'site-home-md';

        // // const dataCache = this.dataCacher.get(keyCache);

        // const dataCache = null;

        // if (dataCache) {

        //     apiDoc = dataCache;

        // } else {

        //     const mdPath = path.join(process.cwd(), 'views', 'about-api.md');

        //     apiDoc = fs.readFileSync(mdPath, 'utf8');

        //     this.dataCacher.set(keyCache, apiDoc);

        // }

        res.render('about', {

            title: 'PUU - About API',

            apiDoc,

        });

    }

    @Get('apiDocs.md')

    getApiDoc(@Res() res: Response) {

        const mdPath = path.join(process.cwd(), 'views', 'about-api.md');

        const md = fs.readFileSync(mdPath, 'utf8');

        res.type('text/markdown').send(md);

    }

    // for API

    @Throttle(AppConstants.throttler_limits.website_send)

    @Post('/language')

    app_language_sel(@Body() body: any, @Res() res: Response) {

        if (body.code && AppConstants.supported_languages.includes(body.code)) {

            this.appSessionService.setLanguage(body.code);

            return res

                .status(HttpStatus.OK)

                .json({ success: true, result: body.code });

        }

        return res.status(HttpStatus.BAD_REQUEST).json({ success: false });

    }

    @Throttle(AppConstants.throttler_limits.brute_force)

    @Get('/ip')

    ip(@Req() req: Request, @Res() res: Response) {

        return res.status(HttpStatus.OK).json({

            ip: req.ip,

            forwarded: req.headers['x-forwarded-for'],

        });

    }

}

on next.js

import fs from 'fs';

import path from 'path';

import { NextResponse } from 'next/server';

export async function GET() {

    const mdPath = path.join(process.cwd(), 'docs', 'about-api.md');

    const md = fs.readFileSync(mdPath, 'utf8');

    return new NextResponse(md, {

        headers: {

            'Content-Type': 'text/markdown; charset=utf-8',

        },

    });

}