import * as ReactDOMServer from 'react-dom/server'
import cookie from 'cookie'
import config from 'config'

// import our main App component
import App from '../../src/App'

import { getLinks } from '../sape'
import { StaticRouter } from 'react-router-dom/server'
import { VisitorProvider } from '../../src/ui/VisitorContext'

import path from 'path'
import fs from 'fs'

// convert a Unicode string to a string in which
// each 16-bit unit occupies only one byte
function toBinary(string) {
    const codeUnits = new Uint16Array(string.length)
    for (let i = 0; i < codeUnits.length; i++) {
        codeUnits[i] = string.charCodeAt(i)
    }
    return Buffer.from(String.fromCharCode(...new Uint8Array(codeUnits.buffer))).toString('base64')
}

const STATIC_ROOT = config.get('service.static_root') || path.resolve(__dirname, 'public')

const serverRenderer = async (req, res) => {

    // point to the html file created by CRA's build tool
    const filePath = path.resolve(STATIC_ROOT, 'index.html')

    // links
    const cookies = cookie.parse(req.headers.cookie || '')

    const links = await getLinks(req.originalUrl, cookies['sape_cookie'])
    fs.readFile(filePath, 'utf8', (err, htmlData) => {
        if (err) {
            console.error('err', err)
            return res.status(404).end()
        }

        const routerContext = {}

        const props = {
            footer: links.join(' ')
        }

        const marker = '<div id="app">'
        const data = htmlData.split(marker)
        const propsData = `<script>window.__PROPS__="${toBinary(JSON.stringify(props))}";</script>${marker}`
        let didError = false
        const { pipe } = ReactDOMServer.renderToPipeableStream(
            <VisitorProvider>
                <StaticRouter location={req.baseUrl} context={routerContext}>
                    <App {...props} />
                </StaticRouter>
            </VisitorProvider>
            , {
                onShellReady() {
                    res.statusCode = didError ? 500 : 200
                    res.setHeader('Content-type', 'text/html')
                    res.write(data[0])
                    res.write(propsData)
                    pipe(res, { end: false })
                },
                onShellError() {
                    didError = true
                    res.statusCode = 500
                    res.setHeader('Content-type', 'text/html')
                    res.send(
                      '<h1>Something went wrong :(</h1>'
                    )
                    res.end()
                  },
                onAllReady() {
                    if (!didError) {
                        res.write(data[1])
                    }
                    res.end()
                },
                onError(err) {
                    didError = true
                    console.log(err)
                }
            })
    })
}

export default serverRenderer