const fs = require('fs')
const path = require('path')
const { createBundleRenderer } = require('vue-server-renderer')
const LRU = require('lru-cache')
const resolve = file => path.resolve(__dirname, file)
const template = fs.readFileSync(resolve('./src/index.template.html'), 'utf-8')

const serverBundle = require('./dist/vue-ssr-server-bundle.json')
const clientManifest = require('./dist/vue-ssr-client-manifest.json')


const renderer = () => {
    // 参考文档
    // https://ssr.vuejs.org/zh/api/#template
    return createBundleRenderer(
        serverBundle,
        Object.assign({clientManifest}, {
            template,
            cache: LRU({
                max: 1000,
                maxAge: 1000 * 60 * 15
            }),
            basedir: resolve('./dist'),
            runInNewContext: false
        })
    )
}

const render =  ({url, title = ''}) => {
    return new Promise (function (resolve, reject) {
        const context = {
            title,
            url,
        }
        renderer().renderToString(context, (err, html) => {
            resolve(html)
        })
    })
}

module.exports = render