website/vite.config.js

import { defineConfig } from 'vite'
import fetch from 'node-fetch'

import { readFile } from 'fs/promises'
import { dirname, resolve } from 'path'
import preactPlugin from '@preact/preset-vite'

const retriveGoRoutes = {
    async build() {
        console.log('Loading routes from disk...')

        const routesRaw = await readFile('out/routes.json', 'utf8')
        return JSON.parse(routesRaw)
    },
    async serve() {
        console.log('Loading routes from go server...')

        const routesReq = await fetch('http://127.0.0.1:4000/api/dev/routes')
        const routes = await routesReq.json()
        console.dir(routes, { depth: null })

        return routes
    },
}

export default defineConfig(async config => {
    let routes = await retriveGoRoutes[config.command]()
    console.dir(routes)

    return {
        root: 'frontend',
        build: {
            outDir: '../out/frontend',
            rollupOptions: {
                input: {
                    'main': resolve(__dirname, 'frontend/pages/index.html'),
                    'lista-utenti': resolve(__dirname, 'frontend/pages/lista-utenti/index.html'),
                },
            },
        },
        server: {
            port: 3000,
            proxy: {
                '/api': 'http://localhost:4000/',
            },
        },
        plugins: [
            preactPlugin(),
            {
                name: 'custom-router',
                configureServer(server) {
                    Object.entries(routes).forEach(([route, file]) => {
                        server.middlewares.use(route, async (req, res, next) => {
                            let htmlPage = await readFile(resolve(__dirname, file), 'utf8')
                            htmlPage = htmlPage.replace(/\.\//g, dirname(file) + '/')

                            const url = file
                            const html = await server.transformIndexHtml(url, htmlPage)

                            console.log(url)

                            res.writeHead(200, { 'Content-Type': 'text/html' }).end(html)
                        })
                    })
                },
            },
        ],
    }
})