import fs from 'node:fs/promises'
import Koa from "koa"
import c2k from 'koa-connect'
import { ViteDevServer } from 'vite'
import Send from 'koa-send'

// Constants
const isProduction = process.env.NODE_ENV === 'production'
const port = process.env.PORT || 5173
const base = process.env.BASE || '/'

// Cached production assets
const templateHtml = isProduction
    ? await fs.readFile('./dist/client/index.html', 'utf-8')
    : ''

const app = new Koa()

// Add Vite or respective production middlewares
/** @type {import('vite').ViteDevServer | undefined} */
let vite: ViteDevServer
if (!isProduction) {
    const { createServer } = await import('vite')
    vite = await createServer({
        server: { middlewareMode: true },
        appType: 'custom',
        base,
    })
    app.use(c2k(vite.middlewares))
} else {
    app.use(Send({ root: 'dist/client', index: false }))
}
app.use(async (ctx, next) => {
    try {
        const url = ctx.path.replace(base, '')
        /** @type {string} */
        let template
        /** @type {import('./client/entry-server.ts').render} */
        let render
        if (!isProduction) {
            // Always read fresh template in development
            template = await fs.readFile('./index.html', 'utf-8')
            template = await vite.transformIndexHtml(url, template)
            render = (await vite.ssrLoadModule('/client/entry-server.ts')).render
        } else {
            template = templateHtml
            // @ts-ignore
            render = (await import('./dist/server/entry-server.js')).render
        }

        const rendered = await render(url)

        const html = template
            .replace(`<!--app-head-->`, rendered.head ?? '')
            .replace(`<!--app-html-->`, rendered.html ?? '')
        ctx.status = 200
        ctx.set({ 'Content-Type': 'text/html' })
        ctx.body = html
    } catch (e: Error | any) {
        vite?.ssrFixStacktrace(e)
        console.log(e.stack)
        ctx.status = 500
        ctx.body = e.stack
    }
    await next()
})

// Start http server
app.listen(port, () => {
    console.log(`Server started at http://localhost:${port}`)
})