import path from 'path'
import fs from 'fs/promises'

import express, { Handler, Router } from 'express'
import morgan from 'morgan'

import { createServer as createViteServer } from 'vite'

import { createApiRouter } from './server/routes.js'
import { RenderFunction } from './shared/ssr.js'

const HTML_ROUTES = ['/', '/login', '/problem/:id', '/admin', '/profile']

const config = {
    isDevelopment: process.env.MODE === 'development',
    port: process.env.PORT || 3000,
}

if (config.isDevelopment) {
    console.log(`[Config] Running in development mode`)
    console.log(`[Config] PORT = ${config.port}`)
}

function mountIndexHtmlRoutes(r: Router, serveIndexHtml: Handler) {
    for (const route of HTML_ROUTES) {
        console.log(`[Server] Mounted index html for "${route}"`)
        r.get(route, serveIndexHtml)
    }

    r.use('*', (_req, res) => {
        res.redirect('/')
    })
}

async function createDevRouter() {
    const r = express.Router()

    const vite = await createViteServer({
        server: { middlewareMode: true },
        appType: 'custom',
    })

    r.use(vite.middlewares)
    mountIndexHtmlRoutes(r, async (req, res, next) => {
        try {
            const indexHtml = await fs.readFile(path.resolve('./index.html'), 'utf-8')
            const transformedTemplate = await vite.transformIndexHtml(req.originalUrl, indexHtml)

            // Load (to be bundled) entry point for server side rendering
            const render: RenderFunction = (await vite.ssrLoadModule('./client/entry-server.tsx'))
                .default

            const { html, metadata } = render(req.originalUrl)

            process.stdout.write('[Metadata] ')
            console.dir(metadata)

            const fullUrl = `${req.protocol}://${req.get('host')}${req.originalUrl}`
            const metaTagsHtml =
                '' +
                (metadata.title
                    ? `<meta property="og:title" content="${metadata.title}" />\n`
                    : '') +
                (metadata.description
                    ? `<meta property="og:description" content="${metadata.description}" />\n`
                    : '') +
                `<meta property="og:url" content="${fullUrl}" />\n`

            res.send(
                transformedTemplate
                    .replace('<!-- INJECT META TAGS -->', metaTagsHtml)
                    .replace('<!-- SSR OUTLET -->', html)
            )
        } catch (error) {
            vite.ssrFixStacktrace(error)
            next(error)
        }
    })

    return r
}

async function createProductionRouter() {
    // Load bundled entry point for server side rendering
    const render: RenderFunction = ((await import('./dist/entry-server/entry-server.js')) as any)
        .default

    const r = express.Router()

    r.use('/', express.static('dist/client'))

    mountIndexHtmlRoutes(r, async (req, res) => {
        const transformedTemplate = await fs.readFile(
            path.resolve('./dist/client/index.html'),
            'utf-8'
        )

        const { html, metadata } = render(req.originalUrl)

        res.send(transformedTemplate.replace('<!-- SSR OUTLET -->', html))
    })

    return r
}

async function main() {
    const app = express()

    app.use(morgan('dev'))

    app.use('/', await createApiRouter())

    if (config.isDevelopment) {
        app.use('/', await createDevRouter())
    } else {
        app.use('/', await createProductionRouter())
    }

    app.listen(config.port, () => {
        console.log(`Listening on port ${config.port}...`)
    })
}

main()